Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Jan. 31, 2016	Jul. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Trading Symbol	AMBA
Entity Registrant Name	AMBARELLA INC
Entity Central Index Key	0001280263
Current Fiscal Year End Date	--01-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	32,333,359
Entity Public Float		$ 3.5

Consolidated Balance Sheets - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Current assets:
Cash and cash equivalents	$ 268,056	$ 170,291
Marketable securities	39,837	37,703
Accounts receivable, net	39,408	40,180
Inventories	18,167	21,693
Restricted cash	7	8
Deferred tax assets, current	0	1,990
Prepaid expenses and other current assets	4,170	3,506
Total current assets	369,645	275,371
Property and equipment, net	3,448	3,075
Deferred tax assets, non-current	4,626	3,936
Intangible assets, net	4,178	0
Goodwill	26,601	0
Other assets	2,117	1,902
Total assets	410,615	284,284
Current liabilities:
Accounts payable	14,175	21,036
Accrued liabilities	23,778	18,699
Income taxes payable	787	748
Deferred tax liabilities, current	0	92
Deferred revenue, current	10,077	4,907
Total current liabilities	48,817	45,482
Deferred revenue, non-current	0	198
Other long-term liabilities	12,342	1,393
Total liabilities	61,159	47,073
Commitments and contingencies (Note 14)	0	0
Shareholders' equity:
Preference shares, $0.00045 par value per share, 20,000,000 shares authorized and no shares issued and outstanding at January 31, 2016 and January 31, 2015, respectively	0	0
Ordinary shares, $0.00045 par value per share, 200,000,000 shares authorized at January 31, 2016 and January 31, 2015, respectively; 32,333,359 shares issued and outstanding at January 31, 2016; 30,837,529 shares issued and outstanding at January 31, 2015	15	14
Additional paid-in capital	176,306	140,564
Accumulated other comprehensive loss	(7)	(1)
Retained earnings	173,142	96,634
Total shareholders’ equity	349,456	237,211
Total liabilities and shareholders' equity	$ 410,615	$ 284,284

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jan. 31, 2016	Jan. 31, 2015
Statement Of Financial Position [Abstract]
Preference shares, par value	$ 0.00045	$ 0.00045
Preference shares, shares authorized	20,000,000	20,000,000
Preference shares, shares issued	0	0
Preference shares, shares outstanding	0	0
Ordinary shares, par value	$ 0.00045	$ 0.00045
Ordinary shares, shares authorized	200,000,000	200,000,000
Ordinary shares, shares issued	32,333,359	30,837,529
Ordinary shares, shares outstanding	32,333,359	30,837,529

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Income Statement [Abstract]
Revenue	$ 316,373	$ 218,278	$ 157,608
Cost of revenue	111,029	79,142	57,761
Gross profit	205,344	139,136	99,847
Operating expenses:
Research and development	82,927	57,978	48,777
Selling, general and administrative	37,738	29,297	23,153
Total operating expenses	120,665	87,275	71,930
Income from operations	84,679	51,861	27,917
Other income (loss), net	530	175	(22)
Income before income taxes	85,209	52,036	27,895
Provision for income taxes	8,701	1,465	2,241
Net income	$ 76,508	$ 50,571	$ 25,654
Net income per share attributable to ordinary shareholders:
Basic	$ 2.42	$ 1.70	$ 0.93
Diluted	$ 2.27	$ 1.57	$ 0.85
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	31,633,936	29,742,653	27,680,778
Diluted	33,755,709	32,278,127	30,172,563

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 76,508	$ 50,571	$ 25,654
Other comprehensive loss:
Unrealized losses on investments	(6)	(1)	0
Other comprehensive loss, net of tax	(6)	(1)	0
Comprehensive income	$ 76,502	$ 50,570	$ 25,654

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Outstanding Ordinary Shares [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
Beginning Balance, Amount at Jan. 31, 2013	$ 112,332	$ 12	$ 91,911		$ 20,409
Beginning Balance, Shares at Jan. 31, 2013		27,035,074
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Amount	$ 6,920	$ 1	6,919
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Shares		1,160,286
Exercise of stock options, Shares	1,160,286
Vesting of early exercised stock options	$ 143		143
Vesting of restricted stock units, Shares		174,888
Employee stock purchase plan, Amount	1,744		1,744
Employee stock purchase plan, Shares		341,973
Exercise of warrants to purchase ordinary shares, Amount	130		130
Exercise of warrants to purchase ordinary shares, Shares		36,292
Stock-based compensation expense related to stock awards granted to employees and consultants	8,535		8,535
Excess income tax benefit associated with stock-based compensation	903		903
Net income	25,654				25,654
Ending Balance, Amount at Jan. 31, 2014	156,361	$ 13	110,285		46,063
Ending Balance, Shares at Jan. 31, 2014		28,748,513
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Amount	$ 8,508	$ 1	8,507
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Shares		1,456,944
Exercise of stock options, Shares	1,456,944
Vesting of early exercised stock options	$ 59		59
Vesting of restricted stock units, Shares		484,296
Employee stock purchase plan, Amount	2,735		2,735
Employee stock purchase plan, Shares		147,776
Stock-based compensation expense related to stock awards granted to employees and consultants	15,692		15,692
Excess income tax benefit associated with stock-based compensation	3,286		3,286
Net unrealized gains (losses) on investments - net of taxes	(1)			$ (1)
Net income	50,571				50,571
Ending Balance, Amount at Jan. 31, 2015	$ 237,211	$ 14	140,564	(1)	96,634
Ending Balance, Shares at Jan. 31, 2015	30,837,529	30,837,529
Exercise of stock options, Amount	$ 5,176	$ 1	5,175
Exercise of stock options, Shares	567,888	567,888
Vesting of restricted stock and restricted stock units, Shares		848,756
Employee stock purchase plan, Amount	$ 3,100		3,100
Employee stock purchase plan, Shares		79,186
Stock-based compensation expense related to stock awards granted to employees and consultants	31,094		31,094
Excess income tax benefit associated with stock-based compensation	(3,627)		(3,627)
Net unrealized gains (losses) on investments - net of taxes	(6)			(6)
Net income	76,508				76,508
Ending Balance, Amount at Jan. 31, 2016	$ 349,456	$ 15	$ 176,306	$ (7)	$ 173,142
Ending Balance, Shares at Jan. 31, 2016	32,333,359	32,333,359

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Cash flows from operating activities:
Net income	$ 76,508	$ 50,571	$ 25,654
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	1,606	1,335	1,096
Amortization/accretion of marketable securities	525	675	0
Loss on disposal of long-lived assets	13	21	13
Stock-based compensation	31,094	15,692	8,535
Excess income tax benefits associated with stock-based compensation	0	(3,286)	(903)
Other non-cash items, net	142	26	0
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	1,262	(21,343)	1,316
Inventories	3,627	(11,241)	(1,534)
Prepaid expenses and other current assets	(572)	(563)	(375)
Deferred tax assets	1,291	(3,184)	(442)
Other assets	(114)	307	63
Accounts payable	(6,880)	12,715	1,270
Accrued liabilities	4,189	6,837	(2,642)
Income taxes payable	244	3,490	807
Deferred tax liabilities	43	83	9
Deferred revenue	4,939	274	1,380
Other long-term liabilities	5,644	(151)	103
Net cash provided by operating activities	123,561	52,258	34,350
Cash flows from investing activities:
Acquisition, net of cash acquired	(29,905)	0	0
Investment in a private company	0	(290)	0
Purchase of investments	(52,786)	(59,807)	0
Sales of investments	17,732	8,729	0
Maturities of investments	32,248	12,668	0
Net proceeds from disposal of fixed assets	0	0	13
Purchase of property and equipment	(2,085)	(1,361)	(1,701)
Net cash used in investing activities	(34,796)	(40,061)	(1,688)
Cash flows from financing activities:
Proceeds from exercise of stock options, warrants, and employee stock purchase plan, net of repurchase of stock options	9,000	11,414	9,360
Payment for initial public offering cost	0	0	(25)
Excess income tax benefits associated with stock-based compensation	0	3,286	903
Net cash provided by financing activities	9,000	14,700	10,238
Net increase in cash and cash equivalents	97,765	26,897	42,900
Cash and cash equivalents at beginning of period	170,291	143,394	100,494
Cash and cash equivalents at end of period	268,056	170,291	143,394
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,618	1,069	1,766
Supplemental disclosure of noncash investing activities:
Increase in accrued liabilities related to non-monetary assets purchases	$ 43	$ 75	$ 24

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Jan. 31, 2016
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies Organization Ambarella, Inc. (the “Company”) was incorporated in the Cayman Islands on January 15, 2004. The Company is a developer of semiconductor processing solutions for video that enable high-definition video capture, sharing and display. The Company combines its processor design capabilities with its expertise in video and image processing, algorithms and software to provide a technology platform that is designed to be easily scalable across multiple applications and enable rapid and efficient product development. The Company’s system-on-a-chip, or SoC, designs fully integrate high-definition video processing, image processing, audio processing and system functions onto a single chip, delivering exceptional video and image quality, differentiated functionality and low power consumption. The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally. Basis of Consolidation The Company’s fiscal year ends on January 31. The consolidated financial statements of the Company and its subsidiaries have been prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”). All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reported periods. Actual results could differ from those estimates. On an ongoing basis, management evaluates its estimates and assumptions, including those related to (i) the collectibility of accounts receivable; (ii) write down of excess and obsolete inventories; (iii) intangible assets and goodwill; (iv) the estimated useful lives of long-lived assets; (v) impairment of long-lived assets and financial instruments; (vi) warranty obligations; (vii) the valuation of stock-based compensation awards and financial instruments; (viii) the probability of performance objectives achievement; (ix) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (x) the recognition and disclosure of contingent liabilities. These estimates and assumptions are based on historical experience and on various other factors which the Company believes to be reasonable under the circumstances. The company may engage third-party valuation specialists to assist with estimates related to the valuation of financial instruments and assets associated with various contractual arrangements. Such estimates often require the selection of appropriate valuation methodologies and significant judgment. Actual results could differ from these estimates under different assumptions or circumstances. Concentration of Risk The Company’s products are manufactured, assembled and tested by third-party contractors located primarily in Asia. The Company does not have long-term agreements with these contractors. A significant disruption in the operations of one or more of these contractors would impact the production of the Company’s products which could have a material adverse effect on its business, financial condition and results of operations. A substantial portion of the Company’s revenue is derived from sales through its logistics provider, Wintech Microelectronics Co., Ltd., or Wintech, which serves as its non-exclusive sales representative in Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationship with Wintech could result in a temporary or permanent loss of revenue and obligation to repurchase unsold product. Furthermore, any credit issues from these two customers could impair their abilities to make timely payment to the Company. See Note 15 for additional information regarding concentration with these two customers. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains its cash primarily in checking and money market accounts with reputable financial institutions. Cash deposits held with these financial institutions may exceed the amount of insurance provided on such deposits. The Company has not experienced any material losses on deposits of its cash. The cash equivalents and marketable securities consist primarily of money market funds, asset-backed securities, commercial paper, U.S. government securities, agency bonds and debt securities of corporations which management assesses to be highly liquid, in order to limit the exposure of each investment. The Company does not hold or issue financial instruments for trading purposes. The Company performs ongoing credit evaluations of each of its customers and adjusts credit limits based upon payment history and the customer’s credit worthiness. The Company regularly monitors collections and payments from its customers. Foreign Currency Transactions The U.S. dollar is the functional currency for the Company and its subsidiaries. Monetary assets and liabilities denominated in non-U.S. currencies are re-measured to U.S. dollars using current exchange rates in effect at the balance sheet date. Nonmonetary assets and liabilities are re-measured to U.S. dollars using historical exchange rates. Monetary and other accounts are re-measured to U.S. dollars using average exchange rates in effect during each period. Gains or losses from foreign currency re-measurement are included in other income (loss), net in the consolidated statements of operations, and, to date, have not been material. Fair Value of Financial Instruments The fair value accounting is applied to all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed in the financial statements on a recurring basis. The carrying amounts reflected in the consolidated balance sheets for cash equivalents, accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature. Cash Equivalents and Marketable Securities The Company considers all highly liquid investments with original maturities of less than three months at the time of purchase to be cash equivalents. Investments that are highly liquid with original maturities at the time of purchase greater than three months are considered as marketable securities. The Company classifies these investments as “available-for-sale” securities carried at fair value, based on quoted market prices of similar assets, with the unrealized gains or losses reported, net of tax, as a separate component of shareholders’ equity and included in accumulated other comprehensive income (loss) in the consolidated balance sheets. The amortization of security premiums and accretion of discounts and the realized gains and losses are both recorded in other income (loss), net in the consolidated statements of operations. The Company reviews its investments for possible other-than-temporary impairments on a regular basis. If any loss on investment is believed to be other-than-temporary, a charge will be recorded and a new cost basis in the investment will be established. In evaluating whether a loss on a security is other-than-temporary, the Company considers the following factors: 1) general market conditions, 2) the duration and extent to which the fair value is less than cost, 3) the Company’s intent and ability to hold the investment. For securities in an unrealized loss position which is deemed to be other-than-temporary, the difference between the security’s then-current amortized cost basis and fair value is separated into (i) the amount of the impairment related to the credit loss (i.e., the credit loss component) and (ii) the amount of the impairment related to all other factors (i.e., the non-credit loss component). The credit loss component is recognized in earnings. The non-credit loss component is recognized in accumulated other comprehensive loss. Due to the relative short term nature of the investments, there have been no other-than-temporary impairments recorded to date. Trade Accounts Receivable and Allowances for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not include finance charges. The Company performs ongoing credit evaluation of its customers and generally requires no collateral. The Company assesses the need for allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments by considering factors such as historical collection experience, credit quality, aging of the accounts receivable balances and current economic conditions that may affect a customer’s ability to pay. There were no material write-offs of accounts receivable for fiscal years 2016, 2015 and 2014, respectively. There was no material allowance for doubtful accounts recorded as of January 31, 2016 and 2015, respectively. Inventories The Company records inventories at the lower of cost or market. The cost includes materials and other production costs and is computed using standard cost on a first-in, first-out basis. Inventory reserves are recorded for estimated obsolescence or unmarketable inventories based on forecast of future demand and market conditions. If actual market conditions are less favorable than projected, or if future demand for the Company’s products decrease, additional inventory write-downs may be required. Once inventory is written down, a new accounting cost basis is established and, accordingly, any associated reserve is not reversed until the inventory is sold or scrapped. There were no material inventory losses recognized for the fiscal years ended January 31, 2016, 2015 and 2014, respectively. Property and Equipment Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of three years for computer equipment, computer software, machinery, equipment and furniture and fixture. Leasehold improvements are amortized over the shorter of the lease term or their estimated useful lives. Repairs and maintenance are charged to expense as incurred. Internal-Use Software The Company capitalizes certain software that is acquired and developed solely for internal use. The capitalization costs include fees for services provided to develop software during the application development stage, costs incurred to obtain software, and certain costs for employees who are directly associated with and who directly devote time to the project. The capitalization begins when the preliminary project stage is completed and ceases no later than the point at which the project is substantially complete and ready for its intended use after all substantial testing is completed. The internal-use software is amortized over its estimated useful life. Repairs and maintenance are charged to expense as incurred. As of January 31, 2016, the Company has capitalized approximately $1.7 million of internal-use software and has been recorded in property and equipment, net on the consolidated balance sheets. Business Combinations and Intangible Assets The Company allocates the fair value of purchase price to the assets acquired and liabilities assumed based on their estimated fair values. The excess of the fair value of purchase price over the fair values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair values of assets acquired and liabilities assumed, especially with respect to intangible assets, management makes significant estimates and assumptions. Critical estimates in valuing certain intangible assets include, but are not limited to, replacement cost. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Goodwill and In-Process Research and Development The Company does not amortize goodwill. Acquired in-process research and development, or IPR&D, is capitalized at fair value as an intangible asset and amortization commences upon completion of the underlying projects. When a project underlying reported IPR&D is completed, the corresponding amount of IPR&D is reclassified as an amortizable purchased intangible asset and is amortized over its estimated useful life. Impairment of Long-Lived Assets Including Goodwill and Other Acquired Intangible Assets The Company reviews property and equipment and intangible assets, excluding goodwill, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset, or asset group, may not be recoverable. Determination of recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. If the carrying amount of an asset or asset group exceeds its estimated undiscounted future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset or asset group exceeds the estimated fair value of the asset or asset group. Fair value is determined based on the estimated discounted future cash flows expected to be generated by the asset or asset group. Events or changes in circumstances that may indicate that an asset is impaired include significant decreases in the market value of an asset, significant underperformance relative to expected historical or projected future results of operations, a change in the extent or manner in which an asset is utilized, significant declines in the estimated fair value of the overall Company for a sustained period, shifts in technology, loss of key management or personnel, changes in the Company’s operating model or strategy and competitive forces. There has been no occurrence of events to date that would trigger an impairment analysis. As such, no impairment charge has been recognized as of January 31, 2016. The Company tests the goodwill for impairment at least annually, or more frequently if events or changes in circumstances indicate that the asset may be impaired. The Company has a single reporting unit for goodwill impairment test purposes based on its business and reporting structure. No goodwill impairment has been identified to date. Cost Method Investment The Company accounts for its investment in a privately held company under the cost method and reports the investment in other assets in the consolidated balance sheets. The Company monitors the carrying value of the investment and records a reduction in carrying value when a decline in value is deemed to be other than temporary. To date, there have been no identified events or changes in circumstances that may have a significant adverse effect on the fair value of this investment and the Company has not recognized any impairment losses related to this investment. Revenue Recognition The Company generates revenue from the sales of its SoCs to OEMs or ODMs, either directly or through logistics providers. Revenue from sales directly to OEMs and ODMs is recognized upon shipment provided persuasive evidence of an arrangement exists, legal title to the products and risk of ownership have transferred, the fee is fixed or determinable, and collection of the resulting receivable is reasonably assured. The Company provides its logistics providers with the rights to return excess levels of inventory and to future price adjustments. Given the inability to reasonably estimate these price changes and returns, revenue and costs related to shipments to logistics providers are deferred until the Company has received notification from its logistics providers that they have sold the Company’s products. Information reported by the Company’s logistics providers includes product resale price, quantity and end customer shipment information as well as remaining inventory on hand. At the time of shipment to a logistics provider, the Company records a trade receivable as there is a legally enforceable right to receive payment, reduces inventory for the value of goods shipped as legal title has passed to the logistics provider and defers the related margin as deferred revenue in the consolidated balance sheets. Any price adjustments are recorded as a change to deferred revenue at the time the adjustments are agreed upon. Arrangements with certain OEM customers provide for pricing that is dependent upon the end products into which the Company’s SoCs are used. These arrangements may also entitle the Company to a share of the product margin ultimately realized by the OEM. The minimum guaranteed amount of revenue related to the sale of products subject to these arrangements is recognized when all other elements of revenue recognition are met. Any amounts at the date of shipment invoiced in excess of the minimum guaranteed contract price are deferred until the additional amounts the Company is entitled to are fixed or determinable. Additional amounts earned by the Company resulting from margin sharing arrangements and determination of the end products into which the products are ultimately incorporated are recognized when end customer sales volume is reported to the Company. The Company also enters into engineering service agreements with certain customers. These agreements may include multiple deliverables, such as software development services, licensing of intellectual property and post-contract customer support, or PCS. The Company does not sell separately any of these components and does not have Vendor Specific Objective Evidence, or VSOE, for the deliverables. Accordingly, revenues from these agreements are deferred for any amounts billed until delivery of all the elements. If the agreements include PCS, the revenues are recognized ratably over the estimated supporting periods. The revenue from engineering service agreements was not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively. Cost of Revenue Cost of revenue includes cost of materials, cost associated with packaging and assembly, testing and shipping, cost of personnel, stock-based compensation, logistics and quality assurance, warranty cost, royalty expense, write-downs of inventories and allocation of overhead. Warranty Costs The Company typically provides warranty on its products. The Company accrues for the estimated warranty costs at the time when revenue is recognized. The warranty accruals are regularly monitored by management based upon historical experience and any specifically identified failures. While the Company engages in extensive product quality assessment, actual product failure rates, material usage or service delivery costs could differ from estimates and revisions to the estimated warranty liability would be required. The Company’s warranty accruals were not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively. Research and Development Research and development costs are expensed as incurred and consist primarily of personnel costs, product development costs, which include engineering services, development software and hardware tools, license fees, cost of fabrication of masks for prototype products, other development materials costs, depreciation of equipment used in research and development and allocation of facilities costs. Selling, General and Administrative Selling, general and administrative expense consists of personnel costs, travel and trade show costs, legal expenses, other professional services and occupancy costs. Advertising expenses were not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively. Operating Leases The Company recognizes rent expense on a straight-line basis over the term of the lease. The difference between rent expense and rent payment is recorded as deferred rent and is included in accrued liabilities in the consolidated balance sheets. Stock-Based Compensation The Company measures stock-based compensation for equity awards granted to employees and directors based on the estimated fair value on the grant date, and recognizes that compensation as expense using the straight-line attribution method for service condition awards or using the graded-vesting attribution method for awards with performance conditions over the requisite service period, which is typically the vesting period of each award. The Company determines the fair value of restricted stock and restricted stock units based on the fair market value of its ordinary shares on the grant date. The Company uses the Black-Scholes option pricing model to determine the fair value of stock options. Determining the fair value of stock options on the grant date requires the input of various assumptions, including stock price of the underlying ordinary share, the exercise price of the stock option, expected volatility, expected term, risk-free interest rate and dividend rate. The expected term is calculated using the simplified method as prescribed in the guidance provided by the Securities and Exchange Commission, as neither relevant historical experience nor other relevant data are available to estimate future exercise behavior. The expected volatility is based on the historical volatilities of similar companies whose share prices are publicly available for a period commensurate with the expected term. The risk-free interest rate is derived from the average U.S. Treasury constant maturity rates during the respective periods commensurate with the expected term. The expected dividend yield is zero because the Company has not historically paid dividends and has no present intention to pay dividends. The Company uses historical data to estimate pre-vesting award forfeitures and records stock-based compensation only for those awards that are expected to vest. Forfeitures are estimated at the time of grant and revised if necessary in subsequent periods if actual forfeitures differ from estimates. The Company recognizes non-employee stock-based compensation expense based on the estimated fair value of the equity instrument. The fair value of the non-employee awards is remeasured at each reporting period until services required under the arrangement are completed, which is the vesting date. Income Taxes The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements or tax returns. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company applies authoritative guidance for the accounting for uncertainty in income taxes. The guidance requires that tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. Upon estimating the Company’s tax positions and tax benefits, the Company considered and evaluated numerous factors, which may require periodic adjustments and which may not reflect the final tax liabilities. The Company adjusts its financial statements to reflect only those tax positions that are more likely than not to be sustained under examination. As part of the process of preparing consolidated financial statements, the Company is required to estimate its taxes in each of the jurisdictions in which it operates. The Company estimates actual current tax exposure together with assessing temporary differences resulting from differing treatment of items, such as accruals and allowances not currently deductible for tax purposes. These differences result in deferred tax assets, which are included in the consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the consolidated statements of operations become deductible expenses under applicable income tax laws, or loss or credit carryforwards are utilized. In assessing whether deferred tax assets may be realized, management considers whether it is more likely than not that some portion or all of deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income. The Company makes estimates and judgments about its future taxable income based on assumptions that are consistent with its plans and estimates. Should the actual amounts differ from estimates, the amount of valuation allowance could be materially impacted. Any adjustment to the deferred tax asset valuation allowance would be recorded in the income statement for the periods in which the adjustment is determined to be required. Net Income Per Ordinary Share The Company applies the two-class method to calculate and present net income per ordinary share. Under the two-class method, net income is allocated between ordinary shares and other participating securities based on their participating rights. Participating securities are defined as securities that may participate in undistributed earnings with ordinary shares, whether that participation is conditioned upon the occurrence of a specified event or not. Basic net income per ordinary share is computed by dividing net income allocable to ordinary shares by the weighted-average number of ordinary shares outstanding for the period. Diluted net income per ordinary share is computed by dividing net income allocable to ordinary shares and income allocable to participating securities, to the extent they are dilutive, by the weighted-average number of ordinary shares outstanding, including the dilutive effects of participating securities on an if-converted basis plus the dilutive effects of ordinary shares. The Company’s potential dilutive ordinary share equivalents consist of incremental ordinary shares issuable upon the exercise of options, upon the issuance of shares pursuant to the Amended and Restated 2012 Employee Stock Purchase Plan, or ESPP, and upon release of vested restricted stock and restricted stock units. The Company performs an assessment as to whether instruments granted in stock-based payment transactions are participating securities. Stock-based payment awards that have not yet vested meet the definition of a participating security provided the right to receive the dividend is non-forfeitable and non-contingent. These participating securities should be included in the computation of basic net income per ordinary share under the two-class method. The Company has concluded that its non-vested early-exercised options meet the definition of a participating security and should be included in the computation of basic net income per ordinary share. Comprehensive Income (Loss) Comprehensive income (loss) includes unrealized gains or losses from available-for-sale securities that are excluded from net income. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The new guidance clarifies the principles and develops a common revenue recognition guidance for U.S. GAAP and International Financial Reporting Standards (the “IFRS”). Under the new guidance, an entity is required to recognize an amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The original effective date of the ASU would have required the public companies to adopt the standard for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted. In July 2015, the FASB voted to amend the ASU by approving a one-year deferral of the effective date as well as providing the option to early adopt the standard on the original effective date. The deferral results in this new revenue standard being effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Accordingly, the Company may adopt the standard in its first quarter of fiscal year 2019. The new revenue guidance may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company is currently evaluating the impact of adoption on its financial position, results of operations and disclosures. In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. In connection with each annual and interim period, management is required to assess whether there is substantial doubt about an entity’s ability to continue as a going concern within one year after the issuance date, and to provide related footnote disclosures in certain circumstances. The new guidance is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. Early adoption is permitted. This ASU is not expected to have an impact on the Company’s financial statements or disclosures. In April 2015, the FASB issued ASU No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement. ASU No. 2015-05 provides the guidance of the accounting for fees paid by a customer in a cloud computing arrangement. If a cloud computing arrangement includes a license to internal-use software, then the entity should account for the software license consistent with the acquisition of internal-use software. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. The new guidance will be effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. An entity can elect to adopt the guidance either (1) prospectively to all arrangements entered into or materially modified after the effective date or (2) retrospectively. This ASU is not expected to have an impact on the Company’s financial statements or disclosures. In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory. The new guidance changes the measurement principle for inventory from the lower of cost or market to lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. It applies to entities that measure inventory using a method other than last-in, first-out (LIFO) and the retail inventory method (RIM). The new guidance will be effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years and should be applied prospectively. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the impact of adoption on its financial position, results of operations and disclosures. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes. To simplify the presentation, the new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. As a result, each jurisdiction will now only have one net noncurrent deferred tax asset or liability. The guidance does not change the existing requirement that only permits offsetting within a jurisdiction – that is, companies are still prohibited from offsetting deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. The new guidance is effective for public business entities in fiscal years beginning after December 15, 2016, including interim periods within those years. Early adoption is permitted. An entity can elect to adopt the guidance either (1) prospectively for all deferred tax assets and liabilities, or (2) retrospectively by reclassifying the comparative balance sheet. If applied prospectively, an entity is required to include a statement that prior periods were not retrospectively adjusted. If applied retrospectively, an entity is also required to include quantitative information about the effects of the change on prior periods. The Company has adopted this standard in the fourth quarter of its fiscal year 2016 on a prospective basis. The adoption of this new guidance resulted in all deferred tax assets and liabilities being classified as noncurrent in the consolidated balance sheet as of January 31, 2016. The presentation of deferred tax assets and liabilities in the consolidated balance sheet as of January 31, 2015, has not been retrospectively adjusted. In February 2016, the FASB issued ASU 2016-02 “Leases (Topic 842).” This standard requires entities that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. The standard is effective for fiscal years and the interim periods within those fiscal years beginning after December 15, 2018. The guidance is required to be applied by the modified retrospective transition approach. Early adoption is permitted. The Company is currently assessing the impact of the adoption of this new guidance on its financial position, results of operations and disclosures.

Financial Instruments and Fair Value

12 Months Ended

Jan. 31, 2016

Investments All Other Investments [Abstract]

Financial Instruments and Fair Value

2. Financial Instruments and Fair Value

The Company invested a portion of its cash in debt securities that are denominated in United States dollars. The investment portfolio consists of money market funds, asset-backed securities, commercial paper, U.S. government securities, agency bonds and debt securities of corporations. All of the investments are classified as available-for-sale securities and reported at fair value in the consolidated balance sheets as follows:

	As of January 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	530	$	—	$	—		$	530
Commercial paper		2,598		—		—			2,598
Corporate bonds		21,342		7		(9	)		21,340
Asset-backed securities		4,586		—		(1	)		4,585
U.S. government securities		9,274		4		(6	)		9,272
Agency bonds		2,044		—		(2	)		2,042
Total cash equivalents and marketable securities	$	40,374	$	11	$	(18	)	$	40,367

	As of January 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	2,427	$	—	$	—		$	2,427
Commercial paper		1,497		—		—			1,497
Corporate bonds		32,356		9		(10	)		32,355
Asset-backed securities		3,851		—		—			3,851
Total cash equivalents and marketable securities	$	40,131	$	9	$	(10	)	$	40,130

	As of
	January 31, 2016		January 31, 2015
	(in thousands)
Included in cash equivalents	$	530	$	2,427
Included in marketable securities		39,837		37,703
Total cash equivalents and marketable securities	$	40,367	$	40,130

The contractual maturities of the investments at January 31, 2016 and 2015 were as follows:

	As of
	January 31, 2016		January 31, 2015
	(in thousands)
Due within one year	$	33,449	$	37,559
Due within one to two years		6,918		2,571
Total cash equivalents and marketable securities	$	40,367	$	40,130

The unrealized losses on the available-for-sale securities were caused by fluctuations in market value and interest rates as a result of the economic environment. As the decline in market value was attributable to changes in market conditions and not credit quality, and because the Company neither intended to sell nor was it more likely than not that it will be required to sell these investments prior to a recovery of par value, the Company did not consider these investments to be other-than temporarily impaired as of January 31, 2016 and 2015, respectively.

The following fair value hierarchy is applied for disclosure of the inputs used to measure fair value. This hierarchy prioritizes the inputs into three broad levels as follows:

Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments.

Level 3—Unobservable inputs based on the Company’s own assumptions used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation.

The Company measures the fair value of money market funds using quoted prices in active markets for identical assets and classifies them within Level 1. The fair value of the Company’s investments in other debt securities are obtained based on quoted prices for similar asserts in active markets, or model driven valuations using significant inputs derived from or corroborated by observable market data and are classified within Level 2.

The following tables present the fair value of the financial instruments measured on a recurring basis as of January 31, 2016 and 2015, respectively:

	As of January 31, 2016
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	530	$	530	$	—	$	—
Commercial paper		2,598		—		2,598		—
Corporate bonds		21,340		—		21,340		—
Asset-backed securities		4,585		—		4,585		—
U.S. government securities		9,272		—		9,272		—
Agency bonds		2,042		—		2,042		—
Total cash equivalents and marketable securities	$	40,367	$	530	$	39,837	$	—

	As of January 31, 2015
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	2,427	$	2,427	$	—	$	—
Commercial paper		1,497		—		1,497		—
Corporate bonds		32,355		—		32,355		—
Asset-backed securities		3,851		—		3,851		—
Total cash equivalents and marketable securities	$	40,130	$	2,427	$	37,703	$	—

Inventories

12 Months Ended

Jan. 31, 2016

Inventory Disclosure [Abstract]

Inventories

3. Inventories

Inventories at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Work-in-progress	$	9,474	$	13,805
Finished goods		8,693		7,888
Total	$	18,167	$	21,693

Property and Equipment, Net

12 Months Ended

Jan. 31, 2016

Property Plant And Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, net

Depreciation expense was approximately $1.6 million, $1.3 million and $1.1 million for the years ended January 31, 2016, 2015 and 2014, respectively. Property and equipment at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016			2015
	(in thousands)
Computer equipment and software	$	6,421		$	5,310
Machinery and equipment		2,706			2,234
Furniture and fixtures		492			456
Leasehold improvements		1,429			1,215
Construction in progress		253			64
		11,301			9,279
Less: accumulated depreciation and amortization		(7,853	)		(6,204	)
Total property and equipment, net	$	3,448		$	3,075

Acquisition	12 Months Ended
Acquisition	Jan. 31, 2016
Business Combinations [Abstract]
Acquisition	5. Acquisition On June 25, 2015, the Company completed the acquisition of VisLab S.r.l. (“VisLab”), a privately held Italian company that develops computer vision and intelligent control systems for automotive and other commercial applications, including Advanced Driver Assistance Systems and several generations of autonomous vehicle driving systems, for $30.0 million in cash. This acquisition will enable extensive and robust computer vision support in future solutions targeting the Company's core markets, including automotive, IP security, wearable, and flying cameras. Of the total purchase price of $30.0 million, $4.1 million was attributed to intangible assets, $25.3 million was attributed to goodwill, and $0.6 million was attributed to net assets acquired. The goodwill represents the excess value of the purchase price over the aggregate fair value of the tangible and intangible assets acquired and primarily represents the intangible assets that do not qualify for separate recognition and the future development initiatives of the assembled workforces. Goodwill is not expected to be deductible for tax purposes. Pro forma and actual result of operations for this acquisition have not been presented because it is not material to the consolidated results of operations.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 5
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1490-128463

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 805
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 805
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Goodwill and Intangible Assets	12 Months Ended
Goodwill and Intangible Assets	Jan. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	6. Goodwill and Intangible Assets On June 25, 2015, the Company completed the acquisition of VisLab. As a result, there was $25.3 million of goodwill and $4.1 million of intangible assets recorded in the consolidated balance sheet. A deferred tax liability of $1.3 million related to the intangible assets was recorded to account for the difference between financial reporting and tax basis at the acquisition date, with an addition to goodwill. The Company does not amortize goodwill. The intangible assets primarily consist of IPR&D. Acquired IPR&D is capitalized at fair value as an intangible asset and amortization commences upon completion of the underlying projects. When a project underlying reported IPR&D is completed, the corresponding amount of IPR&D is reclassified as an amortizable purchased intangible asset and is amortized over its estimated useful life. As of January 31, 2016, there was no IPR&D amortized. And there were no goodwill or intangible asset impairments for the twelve months ended January 31, 2016.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Accrued Liabilities

12 Months Ended

Jan. 31, 2016

Payables And Accruals [Abstract]

Accrued Liabilities

7. Accrued Liabilities

Accrued liabilities at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Accrued employee compensation	$	14,512	$	11,318
Accrued warranty		234		203
Accrued rebates		824		254
Accrued product development costs		6,339		5,004
Other accrued liabilities		1,869		1,920
Total accrued liabilities	$	23,778	$	18,699

Deferred Revenue and Deferred Cost

12 Months Ended

Jan. 31, 2016

Deferred Revenue Disclosure [Abstract]

Deferred Revenue and Deferred Cost

8. Deferred Revenue and Deferred Cost

Deferred revenue and related cost at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016			2015
	(in thousands)
Deferred revenue on product shipments	$	12,201		$	4,663
Deferred revenue from licenses & services		1,653			1,610
Deferred cost of revenue on product shipments		(3,777	)		(1,168	)
Total deferred revenue, net	$	10,077		$	5,105

Other Long-Term Liabilities

12 Months Ended

Jan. 31, 2016

Other Liabilities Disclosure [Abstract]

Other Long-Term Liabilities

9. Other Long-Term Liabilities

Other long-term liabilities at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Unrecognized tax benefits, including interest	$	10,917	$	1,391
Deferred tax liabilities, non-current		1,423		—
Other long-term liabilities		2		2
Total other long-term liabilities	$	12,342	$	1,393

Capital Stock

12 Months Ended

Jan. 31, 2016

Equity [Abstract]

Capital Stock

10. Capital Stock

Preference shares

After completion of the Company’s initial public offering, or IPO, a total of 20,000,000 preference shares, with a $0.00045 par value per share, were authorized. There were no shares issued and outstanding as of January 31, 2016 and 2015, respectively.

Ordinary shares

200,000,000 ordinary shares were authorized at January 31, 2016 and 2015, respectively. As of January 31, 2016 and 2015, the following ordinary shares were reserved for future issuance:

	As of January 31,
	2016		2015
Shares reserved for options, restricted stock and restricted stock units		5,027,475		5,055,845
Shares reserved for employee stock purchase plan		974,273		667,990

Employee Benefits and Stock-based Compensation

12 Months Ended

Jan. 31, 2016

Postemployment Benefits [Abstract]

Employee Benefits and Stock-based Compensation

11. Employee Benefits and Stock-based Compensation

401(k) Plan

The Company maintains a defined contribution 401(k) plan (the “401(k) Plan”) for all of its eligible U.S. employees. Under the 401(k) Plan, eligible employees may contribute up to the Internal Revenue Service annual contribution limitation. The Company is responsible for administrative costs of the Plan. The Company has not had any matching contributions to date.

Stock Option Plans

2004 Stock Plan. The 2004 Stock Plan provides for the grant of incentive stock options (“ISOs”) within the meaning of Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), nonstatutory stock options (“NSOs”), stock purchase rights to acquire restricted stock and restricted stock units. Upon the completion of the IPO, no additional awards will be granted under the 2004 Plan and the 2004 Plan was terminated. However, all outstanding stock options and other awards previously granted under the 2004 Plan will remain subject to the terms of the 2004 Plan.

2012 Equity Incentive Plan. The 2012 Equity Incentive Plan, or EIP, permits the grant of ISOs, within the meaning of Section 422 of the Code, to employees of the Company and any of the Company’s subsidiary corporations, and the grant of NSOs, stock appreciation rights, restricted stock, restricted stock units, performance units, performance shares, deferred stock units and dividend equivalents to employees, directors and consultants of the Company and any of the Company’s subsidiary corporations’ employees and consultants.

The exercise price of ISOs granted to a holder of more than 10% of the voting power of all classes of the Company’s shares shall be no less than 110% of fair market value on the grant date. The exercise price of ISOs granted to other employees and NSOs shall be no less than 100% of fair market value on the grant date. Options granted under the Plan have a term of up to 10 years from grant date. Options granted to new employees generally vest 25% on the first anniversary service date of the grant and remainder vest ratably over the following 36 months. Vesting schedules for other option grants vary and are subject to approval by the board of directors.

Restricted stock and restricted stock units granted to new employees generally vest as to 1/4th of the shares on the first anniversary service date of the grant and 1/16th of the shares vest every 3 months thereafter, so as to be 100% vested on the fourth anniversary of the vesting commencement date. Vesting schedules for other service and performance condition awards vary and are subject to approval by the board of directors; provided that the performance awards shall not vest at all until the performance conditions are achieved and are subject to the award’s holders continuing to provide services to the Company through such vesting dates. The performance condition awards are automatically forfeited in their entirety, without any cost to or action by the Company, if there has been no achievement of the performance. The holders of restricted stock have voting power and other rights with respect to such shares, provided, however, that such shares are held in escrow and subject to forfeiture until the shares vested.

On February 1, 2015 and 2014, the Company added 1,387,689 and 1,297,555 ordinary shares, respectively, to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the EIP. Pursuant to such provision, on February 1st of each fiscal year, the number of ordinary shares reserved for issuance under the EIP is automatically increased by a number equal to the lesser of (i) 3,500,000 ordinary shares, (ii) four and one half percent (4.5%) of the aggregate number of ordinary shares outstanding on January 31st of the preceding fiscal year, or (iii) a lesser number of shares that may be determined by the Company’s Board of Directors.

2012 Employee Stock Purchase Plan. The ESPP permits eligible participants to purchase ordinary shares at a discount through contributions of up to 15% of their eligible compensation, subject to any IRS limitations. The ESPP provides for offering and purchase periods of six months in duration. The purchase price of ordinary shares is 85% of the lower of the closing market price of the Company’s ordinary shares on the first trading day of each offering period or on the purchase date.

On February 1, 2015 and 2014, the Company added 385,469 and 359,356 ordinary shares, respectively, to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the ESPP. Pursuant to such provision, on February 1st of each fiscal year, the number of ordinary shares reserved for issuance under the ESPP is automatically increased by a number equal to the lesser of (i) 1,500,000 ordinary shares, (ii) one and one quarter percent (1.25%) of the aggregate number of ordinary shares outstanding on such date, or (iii) an amount determined by the Company’s Board of Directors or a duly authorized committee of the Board of Directors.

Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
Stock-based compensation:
Cost of revenue	$	657	$	343	$	178
Research and development		19,082		8,654		4,887
Selling, general and administrative		11,355		6,695		3,470
Total stock-based compensation	$	31,094	$	15,692	$	8,535

In fiscal year 2016, the Company granted 268,394 shares of restricted stock awards. As of January 31, 2016, total unrecognized compensation cost related to unvested stock options was $11.4 million and is expected to be recognized over a weighted-average period of 2.47 years. Total unrecognized compensation cost related to unvested restricted stock units was $96.8 million and is expected to be recognized over a weighted-average period of 3.15 years. Total unrecognized compensation cost related to unvested restricted stock was $12.8 million and is expected to be recognized over a weighted-average period of 3.32 years.

The following table sets forth the weighted-average assumptions used to estimate the fair value of the stock options and employee stock purchase plan awards for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
Stock Options:
Volatility		57	%		64	%		65	%
Risk-free interest rate		1.74	%		1.93	%		1.55	%
Expected term (years)	6.08			6.01				6.06
Dividend yield		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		63	%		49	%		52	%
Risk-free interest rate		0.21	%		0.07	%		0.04	%
Expected term (years)		0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%

The following table summarizes stock option activities for the periods indicated:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value of		Remaining		Aggregate
				Weighted-		Average		options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2013		4,344,535		$	6.07
Granted		255,520			18.14	$	10.85
Exercised		(1,160,286	)		5.96			$	18,217
Forfeited		(81,063	)		10.34
Outstanding at January 31, 2014		3,358,706			6.92
Granted		428,781			36.33	$	21.37
Exercised		(1,456,944	)		5.84			$	46,427
Forfeited		(48,634	)		13.38
Outstanding at January 31, 2015		2,281,909			13.00
Granted		179,700			71.36	$	38.81
Exercised		(567,888	)		9.11			$	37,603
Forfeited		(40,331	)		35.65
Outstanding at January 31, 2016		1,853,390		$	19.36					5.89		$	43,396
Exercisable at January 31, 2016		1,363,880		$	10.23						4.93	$	40,341
Vested and expected to vest at January 31, 2016		1,822,252		$	18.84						5.84	$	43,285

Exercisable shares include options with early exercise rights. The vested and expected-to-vest options are calculated based on vesting schedule of each grant as of the reporting date.

The intrinsic value of options outstanding, exercisable and expected-to-vest options are calculated based on the difference between the fair market value of the Company’s ordinary shares on the reporting date and the exercise price. The closing price of the Company’s ordinary shares was $39.68 on January 31, 2016, as reported by The NASDAQ Global Market. The intrinsic value of exercised options is calculated based on the difference between the fair market value of the Company’s ordinary shares on the exercise date and the exercise price.

The following table summarizes restricted stock and restricted stock units activities for the periods indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2013		339,217		$	9.99
Granted		1,265,472			14.78
Vested		(174,888	)		11.91
Forfeited		(19,712	)		11.97
Unvested at January 31, 2014		1,410,089			14.02
Granted		1,111,204			38.60
Vested		(484,296	)		17.39
Forfeited		(56,549	)		19.93
Unvested at January 31, 2015		1,980,448			26.82
Granted		1,314,387			66.14
Vested		(769,779	)		27.82
Forfeited		(29,568	)		42.11
Unvested at January 31, 2016		2,495,488		$	47.04

As of January 31, 2016, the aggregate intrinsic value of unvested restricted stock and restricted stock units was $99.0 million.

Non-employee Stock-based Compensation

The fair value of awards granted to non-employees is determined on the grant date and remeasured at the end of each reporting period until such awards vest. The non-employee stock-based compensation was not material for the years ended January 31, 2016, 2015 and 2014, respectively.

Net Income Per Ordinary Share

12 Months Ended

Jan. 31, 2016

Earnings Per Share [Abstract]

Net Income Per Ordinary Share

12. Net Income Per Ordinary Share

The following table sets forth the computation of basic and diluted net income per ordinary share for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands, except share and per share data)
Numerator:
Net income	$	76,508		$	50,571		$	25,654
Less: amount allocable to unvested early exercised options		—			(11	)		(31	)
Net income allocable to ordinary shareholders - basic	$	76,508		$	50,560		$	25,623
Undistributed earnings reallocated to ordinary shareholders		—			1			2
Net income allocable to ordinary shareholders - diluted	$	76,508		$	50,561		$	25,625
Denominator:
Weighted-average ordinary shares outstanding		31,633,992			29,749,354			27,713,998
Less: weighted-average unvested early exercised options subject to repurchase		(56	)		(6,701	)		(33,220	)
Weighted-average ordinary shares - basic		31,633,936			29,742,653			27,680,778
Effect of potentially dilutive securities:
Employee stock options		1,245,341			1,818,401			2,034,500
Restricted stock and restricted stock units		865,863			704,788			316,350
Employee stock purchase plan		10,569			12,285			138,461
Warrants to purchase ordinary shares		—			—			2,474
Weighted-average ordinary shares - diluted		33,755,709			32,278,127			30,172,563
Net income per ordinary share:
Basic	$	2.42		$	1.70		$	0.93
Diluted	$	2.27		$	1.57		$	0.85

Earnings per share (EPS) of ordinary shares was calculated using the two-class method required for participating securities. Net income has been allocated to the ordinary shares and participating securities based on their respective rights to share in net income and weighted-average outstanding during the periods.

The following weighted-average potentially dilutive securities were excluded from the computation of diluted net income per ordinary share as their effect would have been antidilutive:

	Year Ended January 31,
	2016		2015		2014
Options to purchase ordinary shares		109,958		217,514		183,859
Restricted stock and restricted stock units		163,994		167,702		1,576
Employee stock purchase plan		9,073		36,110		10,597
Early exercised options subject to repurchase		56		6,701		33,220
		283,081		428,027		229,252

Income Taxes

12 Months Ended

Jan. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

Income before income taxes consisted of the following for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
U.S. operations	$	3,190	$	1,978	$	1,990
Non-U.S. operations		82,019		50,058		25,905
Income before income taxes	$	85,209	$	52,036	$	27,895

Income tax provision consisted of the following for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
Current:
U.S. federal tax	$	5,273		$	3,135		$	1,738
U.S. state taxes		541			93			23
Non-U.S. foreign taxes		1,874			1,348			1,058
		7,688			4,576			2,819
Deferred:
U.S. federal tax		1,050			(3,208	)		(952	)
U.S. state taxes		—			—			341
Non-U.S. foreign taxes		(37	)		97			33
		1,013			(3,111	)		(578	)
Provision for income taxes	$	8,701		$	1,465		$	2,241

Income tax provision differed from the amounts computed by applying the U.S. federal income tax rate of 34% to pretax income as a result of the following for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
U.S. federal tax at statutory rate	$	28,971		$	17,692		$	9,484
U.S. state taxes		541			90			361
Non-U.S. foreign tax differential		(26,253	)		(15,644	)		(7,674	)
Stock-based compensation		2,896			1,601			927
U.S. R&D credit		(3,517	)		(2,298	)		(858	)
Valuation allowance		6,090			—			—
Other		(27	)		24			1
Provision for income taxes	$	8,701		$	1,465		$	2,241

Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities at January 31, 2016 and 2015 were as follows:

	As of January 31,
	2016			2015
	(in thousands)
Deferred tax assets:
Federal and state credits	$	11,852		$	6,465
Expenses not currently deductible		2,331			1,590
Stock-based compensation		2,503			2,044
Gross deferred tax assets		16,686			10,099
Valuation allowance		(12,072	)		(3,996	)
Total deferred tax assets	$	4,614		$	6,103
Deferred tax liabilities
Property and equipment		(1,378	)		(199	)
Foreign deferred		(33	)		(70	)
Net deferred tax assets	$	3,203		$	5,834

Tax valuation allowance for the periods indicated below were as follows:

							Deductions
					Additions		Charged to
	Balance at		Additional		Charged to		Expenses		Balance at
	Beginning of		Charged to		Other		or Other		End of
	Period		Expenses		Account		Accounts		Period
	(in thousands)
Tax Valuation Allowance
Year ended January 31, 2016	$	3,996		8,076		—		—	$	12,072
Year ended January 31, 2015	$	2,302		1,694		—		—	$	3,996
Year ended January 31, 2014	$	1,243		1,059		—		—	$	2,302

The Company conducts its business in several countries and regions and is subject to taxation in those jurisdictions. The Company is incorporated in the Cayman Islands with foreign subsidiaries in the U.S., China, Taiwan, Italy and other foreign countries and regions. As such, the Company’s worldwide operating income is subject to varying tax rates and its effective tax rate is highly dependent upon the geographic distribution of its earnings or losses and the tax laws and regulations in each geographical region. Consequently, the Company has experienced lower effective tax rates as a substantial amount of its operations are conducted in lower-tax jurisdictions. If the Company’s operational structure was to change in such a manner that would increase the amount of operating income subject to taxation in higher-tax jurisdictions, or if the Company was to commence operations in jurisdictions assessing relatively higher tax rates, its effective tax rate could fluctuate significantly on a quarterly basis and/or be adversely affected. Dividend distributions received from the Company’s U.S. subsidiary and certain other foreign subsidiaries may be subject to local country withholding taxes when, and if, distributed. Deferred tax liabilities have not been recorded on unremitted earnings of certain subsidiaries because management’s intent is to indefinitely reinvest any undistributed earnings in those subsidiaries. If dividend distributions from those subsidiaries were to occur, the liability as of January 31, 2016 would be $3.9 million. Cumulative undistributed earnings of foreign subsidiaries for which no deferred taxes have been provided approximated $32.8 million at January 31, 2016.

As of January 31, 2016 and 2015, the Company had deferred tax assets (net of deferred tax liabilities) before valuation allowance, of $15.3 million and $9.8 million, respectively. Realization of the deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain.

The Company has $33.1 million and $7.4 million of federal and California net operating loss carryovers as of January 31, 2016, all of which relate to excess tax benefit from stock-based compensation. The authoritative guidance prohibits the recognition of a deferred tax asset for excess stock-based compensation. Such unrecognized deferred tax benefit will be accounted for as a credit to shareholders’ equity, if and when realized, through a reduction in income taxes payable. The federal and California net operating loss carryovers begin to expire in fiscal year 2035.

The Company also has Federal and California state research and development credit carryforwards of approximately $6.1 million and $8.7 million, respectively, at January 31, 2016. The Federal credits begin to expire in fiscal year 2034. The California credits can be carried forward indefinitely.

The Company reports its U.S. state deferred tax assets and related valuation allowance, net of the U.S federal tax rate of 34%. As of January 31, 2016, the Company has recorded a valuation allowance of $12.1 million against all of its U.S. federal research credit and all U.S. state deferred tax assets due to uncertainty regarding the future utilization of these deferred tax assets.

Utilization of the research credit carryforwards may be subject to an annual limitation due to the ownership percentage change limitations as defined by the U.S. Internal Revenue Code Section 382, as amended, and similar state provisions. The annual limitation may result in the expiration of the U.S. Federal and state research credit carryforwards before utilization. The Company does not expect any tax credit carryforwards to expire as a result of a Section 382 limitation.

The Company applies the provisions of FASB’s guidance on accounting for uncertainty in income taxes. As of January 31, 2016, the Company had approximately $30.2 million in unrecognized tax benefits, $6.3 million of which would affect the Company’s effective tax rate if recognized. The following table sets forth a reconciliation of the beginning and ending amount of unrecognized tax benefits:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
Beginning balance:	$	4,671		$	3,583		$	3,018
Additions based on tax positions related to the current year		17,169			1,284			539
Additions for tax positions of prior years		8,810			324			62
Reductions for tax positions in prior years		(37	)		—			—
Settlements for prior periods		—			(43	)		—
Lapse of applicable statute of limitations		(402	)		(477	)		(36	)
Ending balance:	$	30,211		$	4,671		$	3,583

The Company classified $10.8 million and $1.2 million of income tax liabilities as other long term liabilities as of January 31, 2016 and 2015, respectively, because payment of cash or settlement is not anticipated within one year from the balance sheet date.

The Company recognizes interest and penalties related to uncertain tax positions as a component of income tax expense. The Company recorded $6,000, $7,000 and $37,000 of interest expense and penalties related to uncertain tax positions for the years ended January 31, 2016, 2015 and 2014, respectively. The Company recorded noncurrent liabilities of $166,000 and $160,000 related to interest and penalties for uncertain tax positions at January 31, 2016 and 2015, respectively.

The Company is subject to income tax in the U.S. federal jurisdiction and various state and foreign jurisdictions. The U.S. Internal Revenue Service has concluded its audit of the Company’s Federal income tax return for the fiscal year ended January 31, 2010 with no adjustments.

The Company believes that an adequate provision has been made for any adjustments that may result from tax examinations. However, the outcome of tax audits cannot be predicted with certainty. If any issues addressed in the Company’s tax audits are resolved in a manner not consistent with management’s expectations, the Company could be required to adjust its provision for income tax in the period such resolution occurs. Although timing of the resolution and/or closure of audits is highly uncertain, the Company does not believe it is reasonably possible that its unrecognized tax benefits would materially change in the next 12 months.

As of January 31, 2016, the Company’s long-term income taxes payable, including estimated interest and penalties, was approximately $10.9 million. The Company was unable to make a reasonably reliable estimate of the timing of payments in individual years due to uncertainties in the timing of tax audits, if any, or their outcomes.

On July 27, 2015, in Altera Corp. v. Commissioner , the United States Tax Court issued an opinion invalidating the 2003 final Treasury regulations that requires participants in a qualified cost-sharing arrangement to share stock-based compensation. At this time, the U.S. Department of the Treasury has not withdrawn the requirement to include stock-based compensation in intercompany cost-sharing arrangements from its regulations. In February 2016, the IRS appealed the ruling to the United States Court of Appeals for the Ninth Circuit. Due to the uncertainty related to the final resolution of this issue, the Company has not recorded tax benefits in its Consolidated Statements of Operations for the year ended January 31, 2016. The Company will continue to monitor ongoing developments and potential impacts to its consolidated financial statements.

Commitments and Contingencies

12 Months Ended

Jan. 31, 2016

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

14. Commitments and Contingencies

The Company leases its principal facilities and time-based software licenses under operating lease agreements. Net operating lease expenses for the years ended January 31, 2016, 2015 and 2014 were approximately $6.8 million, $5.8 million and $5.0 million, respectively. Future annual minimum payments under these operating agreements with initial lease terms in excess of one year are as follows:

	As of
	January 31, 2016
Fiscal Year	(in thousands)
2017	$	5,844
2018		2,282
2019		1,714
2020		1,532
2021		515
Total future annual minimum lease payments	$	11,887

Contract Manufacturer Commitments

The Company’s components and products are procured and built by independent contract manufacturers based on sales forecasts. These forecasts include estimates of future demand, historical trends, analysis of sales and marketing activities, and adjustment of overall market conditions. The Company regularly issues purchase orders to independent contract manufacturers which are cancelable only upon the agreement between the Company and the third-party. As of January 31, 2016 and 2015, total manufacturing purchase commitments were approximately $19.7 million and $27.5 million, respectively.

Indemnification

The Company, from time to time, in the normal course of business, indemnifies certain vendors with whom it enters into contractual relationships. The Company has agreed to hold the other party harmless against third party claims in connection with the Company’s future products. The Company also indemnifies certain customers against third party claims related to certain intellectual property matters. It is not possible to determine the maximum potential amount of liability under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances that are likely to be involved in each particular claim. The Company has not made payments under these obligations and no liabilities have been recorded for these obligations on the consolidated balance sheets as of January 31, 2016 and 2015, respectively.

Segment Reporting

12 Months Ended

Jan. 31, 2016

Segment Reporting [Abstract]

Segment Reporting

15. Segment Reporting

The Company operates in one reportable segment related to the development and sales of low-power, high-definition video products. The Chief Executive Officer of the Company has been identified as the Chief Operating Decision Maker (the “CODM”) and manages the Company’s operations as a whole and for the purpose of evaluating financial performance and allocating resources, the CODM reviews financial information presented on a consolidated basis accompanied by information by customer and geographic region.

Geographic Revenue

The following table sets forth the Company’s revenue by geographic region for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
Hong Kong	$	284,722	$	196,372	$	135,382
Asia Pacific		3,930		2,358		2,809
United States		8,855		6,677		7,128
North America other than Unites States		9,953		6,076		4,594
Europe		8,913		6,795		7,695
Total revenue	$	316,373	$	218,278	$	157,608

As of January 31, 2016, substantially all of the Company’s long-lived assets were located in the United States and Asia Pacific region with approximate net amount of $1.6 million and $1.5 million, respectively. As of January 31, 2015, substantially all of the Company’s long-lived assets were located in the United States and Asia Pacific region with approximate net amount of $1.8 million and $1.0 million, respectively.

Major Customers

The customers representing 10% or more of revenue and accounts receivable were Wintech, the Company’s logistic provider, and Chicony, a direct ODM customer, which combined accounted for approximately 88%, 89% and 85% of total revenue for the years ended January 31, 2016, 2015 and 2014, respectively. Accounts receivable with these two customers combined accounted for approximately $32.5 million and $36.2 million as of January 31, 2016 and 2015, respectively.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8906-108599

+ Details

Related-Party Transactions	12 Months Ended
Related-Party Transactions	Jan. 31, 2016
Related Party Transactions [Abstract]
Related-Party Transactions	16. Related-Party Transactions The Company considers an entity to be a related party if it owns more than 10% of the Company’s total voting stock at the end of each reporting period or if an officer or employee of an entity also serves on the Company’s board of directors or if it is a significant shareholder and has material business transactions with the Company. In fiscal year 2015, the Company added additional software license commitments to its existing software license agreement with Cadence Design Systems, Inc. (“Cadence”). A member of the Company’s Board of Directors is also the Chief Executive Officer, President and a Director of Cadence. Under these license commitments, the Company committed to pay an aggregate amount of $7.5 million payable through January 2017. The Company paid $2.8 million, $2.3 million and $1.7 million under these agreements for the years ended January 31, 2016, 2015 and 2014, respectively. License expenses related to these agreements included in research and development expense were approximately $2.7 million, $1.9 million and $1.7 million for the years ended January 31, 2016, 2015 and 2014, respectively. In addition to the related party transactions noted above, the Company recognized revenue from sales to Wintech, the Company’s logistics provider. Wintech, along with an affiliate, owned approximately 4.6% of the Company’s voting stock as of January 31, 2013, but has sold such stock and is no longer a significant shareholder of the Company as of January 31, 2016 and 2015, respectively. The Company recognized revenue from sales to Wintech of approximately $210.6 million, $125.1 million and $88.7 million for the years ended January 31, 2016, 2015 and 2014, respectively. As of January 31, 2016 and 2015, the Company had receivables from Wintech of approximately $20.6 million and $12.1 million, respectively.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Jan. 31, 2016
Accounting Policies [Abstract]
Organization	Organization Ambarella, Inc. (the “Company”) was incorporated in the Cayman Islands on January 15, 2004. The Company is a developer of semiconductor processing solutions for video that enable high-definition video capture, sharing and display. The Company combines its processor design capabilities with its expertise in video and image processing, algorithms and software to provide a technology platform that is designed to be easily scalable across multiple applications and enable rapid and efficient product development. The Company’s system-on-a-chip, or SoC, designs fully integrate high-definition video processing, image processing, audio processing and system functions onto a single chip, delivering exceptional video and image quality, differentiated functionality and low power consumption. The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally.
Basis of Consolidation	Basis of Consolidation The Company’s fiscal year ends on January 31. The consolidated financial statements of the Company and its subsidiaries have been prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”). All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reported periods. Actual results could differ from those estimates. On an ongoing basis, management evaluates its estimates and assumptions, including those related to (i) the collectibility of accounts receivable; (ii) write down of excess and obsolete inventories; (iii) intangible assets and goodwill; (iv) the estimated useful lives of long-lived assets; (v) impairment of long-lived assets and financial instruments; (vi) warranty obligations; (vii) the valuation of stock-based compensation awards and financial instruments; (viii) the probability of performance objectives achievement; (ix) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (x) the recognition and disclosure of contingent liabilities. These estimates and assumptions are based on historical experience and on various other factors which the Company believes to be reasonable under the circumstances. The company may engage third-party valuation specialists to assist with estimates related to the valuation of financial instruments and assets associated with various contractual arrangements. Such estimates often require the selection of appropriate valuation methodologies and significant judgment. Actual results could differ from these estimates under different assumptions or circumstances.
Concentration of Risk	Concentration of Risk The Company’s products are manufactured, assembled and tested by third-party contractors located primarily in Asia. The Company does not have long-term agreements with these contractors. A significant disruption in the operations of one or more of these contractors would impact the production of the Company’s products which could have a material adverse effect on its business, financial condition and results of operations. A substantial portion of the Company’s revenue is derived from sales through its logistics provider, Wintech Microelectronics Co., Ltd., or Wintech, which serves as its non-exclusive sales representative in Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationship with Wintech could result in a temporary or permanent loss of revenue and obligation to repurchase unsold product. Furthermore, any credit issues from these two customers could impair their abilities to make timely payment to the Company. See Note 15 for additional information regarding concentration with these two customers. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains its cash primarily in checking and money market accounts with reputable financial institutions. Cash deposits held with these financial institutions may exceed the amount of insurance provided on such deposits. The Company has not experienced any material losses on deposits of its cash. The cash equivalents and marketable securities consist primarily of money market funds, asset-backed securities, commercial paper, U.S. government securities, agency bonds and debt securities of corporations which management assesses to be highly liquid, in order to limit the exposure of each investment. The Company does not hold or issue financial instruments for trading purposes. The Company performs ongoing credit evaluations of each of its customers and adjusts credit limits based upon payment history and the customer’s credit worthiness. The Company regularly monitors collections and payments from its customers.
Foreign Currency Transactions	Foreign Currency Transactions The U.S. dollar is the functional currency for the Company and its subsidiaries. Monetary assets and liabilities denominated in non-U.S. currencies are re-measured to U.S. dollars using current exchange rates in effect at the balance sheet date. Nonmonetary assets and liabilities are re-measured to U.S. dollars using historical exchange rates. Monetary and other accounts are re-measured to U.S. dollars using average exchange rates in effect during each period. Gains or losses from foreign currency re-measurement are included in other income (loss), net in the consolidated statements of operations, and, to date, have not been material.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value accounting is applied to all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed in the financial statements on a recurring basis. The carrying amounts reflected in the consolidated balance sheets for cash equivalents, accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities The Company considers all highly liquid investments with original maturities of less than three months at the time of purchase to be cash equivalents. Investments that are highly liquid with original maturities at the time of purchase greater than three months are considered as marketable securities. The Company classifies these investments as “available-for-sale” securities carried at fair value, based on quoted market prices of similar assets, with the unrealized gains or losses reported, net of tax, as a separate component of shareholders’ equity and included in accumulated other comprehensive income (loss) in the consolidated balance sheets. The amortization of security premiums and accretion of discounts and the realized gains and losses are both recorded in other income (loss), net in the consolidated statements of operations. The Company reviews its investments for possible other-than-temporary impairments on a regular basis. If any loss on investment is believed to be other-than-temporary, a charge will be recorded and a new cost basis in the investment will be established. In evaluating whether a loss on a security is other-than-temporary, the Company considers the following factors: 1) general market conditions, 2) the duration and extent to which the fair value is less than cost, 3) the Company’s intent and ability to hold the investment. For securities in an unrealized loss position which is deemed to be other-than-temporary, the difference between the security’s then-current amortized cost basis and fair value is separated into (i) the amount of the impairment related to the credit loss (i.e., the credit loss component) and (ii) the amount of the impairment related to all other factors (i.e., the non-credit loss component). The credit loss component is recognized in earnings. The non-credit loss component is recognized in accumulated other comprehensive loss. Due to the relative short term nature of the investments, there have been no other-than-temporary impairments recorded to date.
Trade Accounts Receivable and Allowances for Doubtful Accounts	Trade Accounts Receivable and Allowances for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not include finance charges. The Company performs ongoing credit evaluation of its customers and generally requires no collateral. The Company assesses the need for allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments by considering factors such as historical collection experience, credit quality, aging of the accounts receivable balances and current economic conditions that may affect a customer’s ability to pay. There were no material write-offs of accounts receivable for fiscal years 2016, 2015 and 2014, respectively. There was no material allowance for doubtful accounts recorded as of January 31, 2016 and 2015, respectively.
Inventories	Inventories The Company records inventories at the lower of cost or market. The cost includes materials and other production costs and is computed using standard cost on a first-in, first-out basis. Inventory reserves are recorded for estimated obsolescence or unmarketable inventories based on forecast of future demand and market conditions. If actual market conditions are less favorable than projected, or if future demand for the Company’s products decrease, additional inventory write-downs may be required. Once inventory is written down, a new accounting cost basis is established and, accordingly, any associated reserve is not reversed until the inventory is sold or scrapped. There were no material inventory losses recognized for the fiscal years ended January 31, 2016, 2015 and 2014, respectively.
Property and Equipment	Property and Equipment Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of three years for computer equipment, computer software, machinery, equipment and furniture and fixture. Leasehold improvements are amortized over the shorter of the lease term or their estimated useful lives. Repairs and maintenance are charged to expense as incurred.
Internal-Use Software	Internal-Use Software The Company capitalizes certain software that is acquired and developed solely for internal use. The capitalization costs include fees for services provided to develop software during the application development stage, costs incurred to obtain software, and certain costs for employees who are directly associated with and who directly devote time to the project. The capitalization begins when the preliminary project stage is completed and ceases no later than the point at which the project is substantially complete and ready for its intended use after all substantial testing is completed. The internal-use software is amortized over its estimated useful life. Repairs and maintenance are charged to expense as incurred. As of January 31, 2016, the Company has capitalized approximately $1.7 million of internal-use software and has been recorded in property and equipment, net on the consolidated balance sheets.
Business Combinations and Intangible Assets	Business Combinations and Intangible Assets The Company allocates the fair value of purchase price to the assets acquired and liabilities assumed based on their estimated fair values. The excess of the fair value of purchase price over the fair values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair values of assets acquired and liabilities assumed, especially with respect to intangible assets, management makes significant estimates and assumptions. Critical estimates in valuing certain intangible assets include, but are not limited to, replacement cost. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates.
Goodwill and In-Process Research and Development	Goodwill and In-Process Research and Development The Company does not amortize goodwill. Acquired in-process research and development, or IPR&D, is capitalized at fair value as an intangible asset and amortization commences upon completion of the underlying projects. When a project underlying reported IPR&D is completed, the corresponding amount of IPR&D is reclassified as an amortizable purchased intangible asset and is amortized over its estimated useful life.
Impairment of Long-Lived Assets Including Goodwill and Other Acquired Intangible Assets	Impairment of Long-Lived Assets Including Goodwill and Other Acquired Intangible Assets The Company reviews property and equipment and intangible assets, excluding goodwill, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset, or asset group, may not be recoverable. Determination of recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. If the carrying amount of an asset or asset group exceeds its estimated undiscounted future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset or asset group exceeds the estimated fair value of the asset or asset group. Fair value is determined based on the estimated discounted future cash flows expected to be generated by the asset or asset group. Events or changes in circumstances that may indicate that an asset is impaired include significant decreases in the market value of an asset, significant underperformance relative to expected historical or projected future results of operations, a change in the extent or manner in which an asset is utilized, significant declines in the estimated fair value of the overall Company for a sustained period, shifts in technology, loss of key management or personnel, changes in the Company’s operating model or strategy and competitive forces. There has been no occurrence of events to date that would trigger an impairment analysis. As such, no impairment charge has been recognized as of January 31, 2016. The Company tests the goodwill for impairment at least annually, or more frequently if events or changes in circumstances indicate that the asset may be impaired. The Company has a single reporting unit for goodwill impairment test purposes based on its business and reporting structure. No goodwill impairment has been identified to date.
Cost Method Investment	Cost Method Investment The Company accounts for its investment in a privately held company under the cost method and reports the investment in other assets in the consolidated balance sheets. The Company monitors the carrying value of the investment and records a reduction in carrying value when a decline in value is deemed to be other than temporary. To date, there have been no identified events or changes in circumstances that may have a significant adverse effect on the fair value of this investment and the Company has not recognized any impairment losses related to this investment.
Revenue Recognition	Revenue Recognition The Company generates revenue from the sales of its SoCs to OEMs or ODMs, either directly or through logistics providers. Revenue from sales directly to OEMs and ODMs is recognized upon shipment provided persuasive evidence of an arrangement exists, legal title to the products and risk of ownership have transferred, the fee is fixed or determinable, and collection of the resulting receivable is reasonably assured. The Company provides its logistics providers with the rights to return excess levels of inventory and to future price adjustments. Given the inability to reasonably estimate these price changes and returns, revenue and costs related to shipments to logistics providers are deferred until the Company has received notification from its logistics providers that they have sold the Company’s products. Information reported by the Company’s logistics providers includes product resale price, quantity and end customer shipment information as well as remaining inventory on hand. At the time of shipment to a logistics provider, the Company records a trade receivable as there is a legally enforceable right to receive payment, reduces inventory for the value of goods shipped as legal title has passed to the logistics provider and defers the related margin as deferred revenue in the consolidated balance sheets. Any price adjustments are recorded as a change to deferred revenue at the time the adjustments are agreed upon. Arrangements with certain OEM customers provide for pricing that is dependent upon the end products into which the Company’s SoCs are used. These arrangements may also entitle the Company to a share of the product margin ultimately realized by the OEM. The minimum guaranteed amount of revenue related to the sale of products subject to these arrangements is recognized when all other elements of revenue recognition are met. Any amounts at the date of shipment invoiced in excess of the minimum guaranteed contract price are deferred until the additional amounts the Company is entitled to are fixed or determinable. Additional amounts earned by the Company resulting from margin sharing arrangements and determination of the end products into which the products are ultimately incorporated are recognized when end customer sales volume is reported to the Company. The Company also enters into engineering service agreements with certain customers. These agreements may include multiple deliverables, such as software development services, licensing of intellectual property and post-contract customer support, or PCS. The Company does not sell separately any of these components and does not have Vendor Specific Objective Evidence, or VSOE, for the deliverables. Accordingly, revenues from these agreements are deferred for any amounts billed until delivery of all the elements. If the agreements include PCS, the revenues are recognized ratably over the estimated supporting periods. The revenue from engineering service agreements was not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively.
Cost of Revenue	Cost of Revenue Cost of revenue includes cost of materials, cost associated with packaging and assembly, testing and shipping, cost of personnel, stock-based compensation, logistics and quality assurance, warranty cost, royalty expense, write-downs of inventories and allocation of overhead.
Warranty Costs	Warranty Costs The Company typically provides warranty on its products. The Company accrues for the estimated warranty costs at the time when revenue is recognized. The warranty accruals are regularly monitored by management based upon historical experience and any specifically identified failures. While the Company engages in extensive product quality assessment, actual product failure rates, material usage or service delivery costs could differ from estimates and revisions to the estimated warranty liability would be required. The Company’s warranty accruals were not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively.
Research and Development	Research and Development Research and development costs are expensed as incurred and consist primarily of personnel costs, product development costs, which include engineering services, development software and hardware tools, license fees, cost of fabrication of masks for prototype products, other development materials costs, depreciation of equipment used in research and development and allocation of facilities costs.
Selling, General and Administrative	Selling, General and Administrative Selling, general and administrative expense consists of personnel costs, travel and trade show costs, legal expenses, other professional services and occupancy costs. Advertising expenses were not material for the fiscal years ended January 31, 2016, 2015 and 2014, respectively.
Operating Leases	Operating Leases The Company recognizes rent expense on a straight-line basis over the term of the lease. The difference between rent expense and rent payment is recorded as deferred rent and is included in accrued liabilities in the consolidated balance sheets.
Stock-Based Compensation	Stock-Based Compensation The Company measures stock-based compensation for equity awards granted to employees and directors based on the estimated fair value on the grant date, and recognizes that compensation as expense using the straight-line attribution method for service condition awards or using the graded-vesting attribution method for awards with performance conditions over the requisite service period, which is typically the vesting period of each award. The Company determines the fair value of restricted stock and restricted stock units based on the fair market value of its ordinary shares on the grant date. The Company uses the Black-Scholes option pricing model to determine the fair value of stock options. Determining the fair value of stock options on the grant date requires the input of various assumptions, including stock price of the underlying ordinary share, the exercise price of the stock option, expected volatility, expected term, risk-free interest rate and dividend rate. The expected term is calculated using the simplified method as prescribed in the guidance provided by the Securities and Exchange Commission, as neither relevant historical experience nor other relevant data are available to estimate future exercise behavior. The expected volatility is based on the historical volatilities of similar companies whose share prices are publicly available for a period commensurate with the expected term. The risk-free interest rate is derived from the average U.S. Treasury constant maturity rates during the respective periods commensurate with the expected term. The expected dividend yield is zero because the Company has not historically paid dividends and has no present intention to pay dividends. The Company uses historical data to estimate pre-vesting award forfeitures and records stock-based compensation only for those awards that are expected to vest. Forfeitures are estimated at the time of grant and revised if necessary in subsequent periods if actual forfeitures differ from estimates. The Company recognizes non-employee stock-based compensation expense based on the estimated fair value of the equity instrument. The fair value of the non-employee awards is remeasured at each reporting period until services required under the arrangement are completed, which is the vesting date.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements or tax returns. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company applies authoritative guidance for the accounting for uncertainty in income taxes. The guidance requires that tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. Upon estimating the Company’s tax positions and tax benefits, the Company considered and evaluated numerous factors, which may require periodic adjustments and which may not reflect the final tax liabilities. The Company adjusts its financial statements to reflect only those tax positions that are more likely than not to be sustained under examination. As part of the process of preparing consolidated financial statements, the Company is required to estimate its taxes in each of the jurisdictions in which it operates. The Company estimates actual current tax exposure together with assessing temporary differences resulting from differing treatment of items, such as accruals and allowances not currently deductible for tax purposes. These differences result in deferred tax assets, which are included in the consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the consolidated statements of operations become deductible expenses under applicable income tax laws, or loss or credit carryforwards are utilized. In assessing whether deferred tax assets may be realized, management considers whether it is more likely than not that some portion or all of deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income. The Company makes estimates and judgments about its future taxable income based on assumptions that are consistent with its plans and estimates. Should the actual amounts differ from estimates, the amount of valuation allowance could be materially impacted. Any adjustment to the deferred tax asset valuation allowance would be recorded in the income statement for the periods in which the adjustment is determined to be required.
Net Income Per Ordinary Share	Net Income Per Ordinary Share The Company applies the two-class method to calculate and present net income per ordinary share. Under the two-class method, net income is allocated between ordinary shares and other participating securities based on their participating rights. Participating securities are defined as securities that may participate in undistributed earnings with ordinary shares, whether that participation is conditioned upon the occurrence of a specified event or not. Basic net income per ordinary share is computed by dividing net income allocable to ordinary shares by the weighted-average number of ordinary shares outstanding for the period. Diluted net income per ordinary share is computed by dividing net income allocable to ordinary shares and income allocable to participating securities, to the extent they are dilutive, by the weighted-average number of ordinary shares outstanding, including the dilutive effects of participating securities on an if-converted basis plus the dilutive effects of ordinary shares. The Company’s potential dilutive ordinary share equivalents consist of incremental ordinary shares issuable upon the exercise of options, upon the issuance of shares pursuant to the Amended and Restated 2012 Employee Stock Purchase Plan, or ESPP, and upon release of vested restricted stock and restricted stock units. The Company performs an assessment as to whether instruments granted in stock-based payment transactions are participating securities. Stock-based payment awards that have not yet vested meet the definition of a participating security provided the right to receive the dividend is non-forfeitable and non-contingent. These participating securities should be included in the computation of basic net income per ordinary share under the two-class method. The Company has concluded that its non-vested early-exercised options meet the definition of a participating security and should be included in the computation of basic net income per ordinary share.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes unrealized gains or losses from available-for-sale securities that are excluded from net income.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The new guidance clarifies the principles and develops a common revenue recognition guidance for U.S. GAAP and International Financial Reporting Standards (the “IFRS”). Under the new guidance, an entity is required to recognize an amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The original effective date of the ASU would have required the public companies to adopt the standard for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted. In July 2015, the FASB voted to amend the ASU by approving a one-year deferral of the effective date as well as providing the option to early adopt the standard on the original effective date. The deferral results in this new revenue standard being effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Accordingly, the Company may adopt the standard in its first quarter of fiscal year 2019. The new revenue guidance may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company is currently evaluating the impact of adoption on its financial position, results of operations and disclosures. In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. In connection with each annual and interim period, management is required to assess whether there is substantial doubt about an entity’s ability to continue as a going concern within one year after the issuance date, and to provide related footnote disclosures in certain circumstances. The new guidance is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. Early adoption is permitted. This ASU is not expected to have an impact on the Company’s financial statements or disclosures. In April 2015, the FASB issued ASU No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement. ASU No. 2015-05 provides the guidance of the accounting for fees paid by a customer in a cloud computing arrangement. If a cloud computing arrangement includes a license to internal-use software, then the entity should account for the software license consistent with the acquisition of internal-use software. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. The new guidance will be effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. An entity can elect to adopt the guidance either (1) prospectively to all arrangements entered into or materially modified after the effective date or (2) retrospectively. This ASU is not expected to have an impact on the Company’s financial statements or disclosures. In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory. The new guidance changes the measurement principle for inventory from the lower of cost or market to lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. It applies to entities that measure inventory using a method other than last-in, first-out (LIFO) and the retail inventory method (RIM). The new guidance will be effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years and should be applied prospectively. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the impact of adoption on its financial position, results of operations and disclosures. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes. To simplify the presentation, the new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. As a result, each jurisdiction will now only have one net noncurrent deferred tax asset or liability. The guidance does not change the existing requirement that only permits offsetting within a jurisdiction – that is, companies are still prohibited from offsetting deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. The new guidance is effective for public business entities in fiscal years beginning after December 15, 2016, including interim periods within those years. Early adoption is permitted. An entity can elect to adopt the guidance either (1) prospectively for all deferred tax assets and liabilities, or (2) retrospectively by reclassifying the comparative balance sheet. If applied prospectively, an entity is required to include a statement that prior periods were not retrospectively adjusted. If applied retrospectively, an entity is also required to include quantitative information about the effects of the change on prior periods. The Company has adopted this standard in the fourth quarter of its fiscal year 2016 on a prospective basis. The adoption of this new guidance resulted in all deferred tax assets and liabilities being classified as noncurrent in the consolidated balance sheet as of January 31, 2016. The presentation of deferred tax assets and liabilities in the consolidated balance sheet as of January 31, 2015, has not been retrospectively adjusted. In February 2016, the FASB issued ASU 2016-02 “Leases (Topic 842).” This standard requires entities that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. The standard is effective for fiscal years and the interim periods within those fiscal years beginning after December 15, 2018. The guidance is required to be applied by the modified retrospective transition approach. Early adoption is permitted. The Company is currently assessing the impact of the adoption of this new guidance on its financial position, results of operations and disclosures.

Financial Instruments and Fair Value (Tables)

12 Months Ended

Jan. 31, 2016

Investments All Other Investments [Abstract]

Schedule of Available-for-Sale Securities at Fair Value

All of the investments are classified as available-for-sale securities and reported at fair value in the consolidated balance sheets as follows:

	As of January 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	530	$	—	$	—		$	530
Commercial paper		2,598		—		—			2,598
Corporate bonds		21,342		7		(9	)		21,340
Asset-backed securities		4,586		—		(1	)		4,585
U.S. government securities		9,274		4		(6	)		9,272
Agency bonds		2,044		—		(2	)		2,042
Total cash equivalents and marketable securities	$	40,374	$	11	$	(18	)	$	40,367

	As of January 31, 2015
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	2,427	$	—	$	—		$	2,427
Commercial paper		1,497		—		—			1,497
Corporate bonds		32,356		9		(10	)		32,355
Asset-backed securities		3,851		—		—			3,851
Total cash equivalents and marketable securities	$	40,131	$	9	$	(10	)	$	40,130

Schedule of Cash Equivalents and Marketable Securities

	As of
	January 31, 2016		January 31, 2015
	(in thousands)
Included in cash equivalents	$	530	$	2,427
Included in marketable securities		39,837		37,703
Total cash equivalents and marketable securities	$	40,367	$	40,130

Summary of Contractual Maturities of Investments

The contractual maturities of the investments at January 31, 2016 and 2015 were as follows:

	As of
	January 31, 2016		January 31, 2015
	(in thousands)
Due within one year	$	33,449	$	37,559
Due within one to two years		6,918		2,571
Total cash equivalents and marketable securities	$	40,367	$	40,130

Schedule of Fair Value of Financial Instruments Measured on Recurring Basis

The following tables present the fair value of the financial instruments measured on a recurring basis as of January 31, 2016 and 2015, respectively:

	As of January 31, 2016
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	530	$	530	$	—	$	—
Commercial paper		2,598		—		2,598		—
Corporate bonds		21,340		—		21,340		—
Asset-backed securities		4,585		—		4,585		—
U.S. government securities		9,272		—		9,272		—
Agency bonds		2,042		—		2,042		—
Total cash equivalents and marketable securities	$	40,367	$	530	$	39,837	$	—

	As of January 31, 2015
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	2,427	$	2,427	$	—	$	—
Commercial paper		1,497		—		1,497		—
Corporate bonds		32,355		—		32,355		—
Asset-backed securities		3,851		—		3,851		—
Total cash equivalents and marketable securities	$	40,130	$	2,427	$	37,703	$	—

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Inventories (Tables)

12 Months Ended

Jan. 31, 2016

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Work-in-progress	$	9,474	$	13,805
Finished goods		8,693		7,888
Total	$	18,167	$	21,693

Property and Equipment, Net (Tables)

12 Months Ended

Jan. 31, 2016

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016			2015
	(in thousands)
Computer equipment and software	$	6,421		$	5,310
Machinery and equipment		2,706			2,234
Furniture and fixtures		492			456
Leasehold improvements		1,429			1,215
Construction in progress		253			64
		11,301			9,279
Less: accumulated depreciation and amortization		(7,853	)		(6,204	)
Total property and equipment, net	$	3,448		$	3,075

Accrued Liabilities (Tables)

12 Months Ended

Jan. 31, 2016

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Accrued employee compensation	$	14,512	$	11,318
Accrued warranty		234		203
Accrued rebates		824		254
Accrued product development costs		6,339		5,004
Other accrued liabilities		1,869		1,920
Total accrued liabilities	$	23,778	$	18,699

Deferred Revenue and Deferred Cost (Tables)

12 Months Ended

Jan. 31, 2016

Deferred Revenue Disclosure [Abstract]

Schedule of Deferred Revenue and Related Cost

Deferred revenue and related cost at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016			2015
	(in thousands)
Deferred revenue on product shipments	$	12,201		$	4,663
Deferred revenue from licenses & services		1,653			1,610
Deferred cost of revenue on product shipments		(3,777	)		(1,168	)
Total deferred revenue, net	$	10,077		$	5,105

Other Long-Term Liabilities (Tables)

12 Months Ended

Jan. 31, 2016

Other Liabilities Disclosure [Abstract]

Schedule of Other Long-Term Liabilities

Other long-term liabilities at January 31, 2016 and 2015 consisted of the following:

	As of January 31,
	2016		2015
	(in thousands)
Unrecognized tax benefits, including interest	$	10,917	$	1,391
Deferred tax liabilities, non-current		1,423		—
Other long-term liabilities		2		2
Total other long-term liabilities	$	12,342	$	1,393

Capital Stock (Tables)

12 Months Ended

Jan. 31, 2016

Equity [Abstract]

Schedule of Ordinary Shares Reserved for Future Issuance

As of January 31, 2016 and 2015, the following ordinary shares were reserved for future issuance:

	As of January 31,
	2016		2015
Shares reserved for options, restricted stock and restricted stock units		5,027,475		5,055,845
Shares reserved for employee stock purchase plan		974,273		667,990

Employee Benefits and Stock-based Compensation (Tables)

12 Months Ended

Jan. 31, 2016

Postemployment Benefits [Abstract]

Classification of Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
Stock-based compensation:
Cost of revenue	$	657	$	343	$	178
Research and development		19,082		8,654		4,887
Selling, general and administrative		11,355		6,695		3,470
Total stock-based compensation	$	31,094	$	15,692	$	8,535

Weighted-Average Assumptions Used to Estimate Fair Value

The following table sets forth the weighted-average assumptions used to estimate the fair value of the stock options and employee stock purchase plan awards for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
Stock Options:
Volatility		57	%		64	%		65	%
Risk-free interest rate		1.74	%		1.93	%		1.55	%
Expected term (years)	6.08			6.01				6.06
Dividend yield		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		63	%		49	%		52	%
Risk-free interest rate		0.21	%		0.07	%		0.04	%
Expected term (years)		0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%

Stock Option Activities

The following table summarizes stock option activities for the periods indicated:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value of		Remaining		Aggregate
				Weighted-		Average		options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2013		4,344,535		$	6.07
Granted		255,520			18.14	$	10.85
Exercised		(1,160,286	)		5.96			$	18,217
Forfeited		(81,063	)		10.34
Outstanding at January 31, 2014		3,358,706			6.92
Granted		428,781			36.33	$	21.37
Exercised		(1,456,944	)		5.84			$	46,427
Forfeited		(48,634	)		13.38
Outstanding at January 31, 2015		2,281,909			13.00
Granted		179,700			71.36	$	38.81
Exercised		(567,888	)		9.11			$	37,603
Forfeited		(40,331	)		35.65
Outstanding at January 31, 2016		1,853,390		$	19.36					5.89		$	43,396
Exercisable at January 31, 2016		1,363,880		$	10.23						4.93	$	40,341
Vested and expected to vest at January 31, 2016		1,822,252		$	18.84						5.84	$	43,285

Restricted Stock and Restricted Stock Units Activities

The following table summarizes restricted stock and restricted stock units activities for the periods indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2013		339,217		$	9.99
Granted		1,265,472			14.78
Vested		(174,888	)		11.91
Forfeited		(19,712	)		11.97
Unvested at January 31, 2014		1,410,089			14.02
Granted		1,111,204			38.60
Vested		(484,296	)		17.39
Forfeited		(56,549	)		19.93
Unvested at January 31, 2015		1,980,448			26.82
Granted		1,314,387			66.14
Vested		(769,779	)		27.82
Forfeited		(29,568	)		42.11
Unvested at January 31, 2016		2,495,488		$	47.04

Net Income Per Ordinary Share (Tables)

12 Months Ended

Jan. 31, 2016

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Income Per Ordinary Share

The following table sets forth the computation of basic and diluted net income per ordinary share for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands, except share and per share data)
Numerator:
Net income	$	76,508		$	50,571		$	25,654
Less: amount allocable to unvested early exercised options		—			(11	)		(31	)
Net income allocable to ordinary shareholders - basic	$	76,508		$	50,560		$	25,623
Undistributed earnings reallocated to ordinary shareholders		—			1			2
Net income allocable to ordinary shareholders - diluted	$	76,508		$	50,561		$	25,625
Denominator:
Weighted-average ordinary shares outstanding		31,633,992			29,749,354			27,713,998
Less: weighted-average unvested early exercised options subject to repurchase		(56	)		(6,701	)		(33,220	)
Weighted-average ordinary shares - basic		31,633,936			29,742,653			27,680,778
Effect of potentially dilutive securities:
Employee stock options		1,245,341			1,818,401			2,034,500
Restricted stock and restricted stock units		865,863			704,788			316,350
Employee stock purchase plan		10,569			12,285			138,461
Warrants to purchase ordinary shares		—			—			2,474
Weighted-average ordinary shares - diluted		33,755,709			32,278,127			30,172,563
Net income per ordinary share:
Basic	$	2.42		$	1.70		$	0.93
Diluted	$	2.27		$	1.57		$	0.85

Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Net Income Per Ordinary Share

The following weighted-average potentially dilutive securities were excluded from the computation of diluted net income per ordinary share as their effect would have been antidilutive:

	Year Ended January 31,
	2016		2015		2014
Options to purchase ordinary shares		109,958		217,514		183,859
Restricted stock and restricted stock units		163,994		167,702		1,576
Employee stock purchase plan		9,073		36,110		10,597
Early exercised options subject to repurchase		56		6,701		33,220
		283,081		428,027		229,252

Income Taxes (Tables)

12 Months Ended

Jan. 31, 2016

Income Tax Disclosure [Abstract]

Summary of Income before Income Taxes

Income before income taxes consisted of the following for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
U.S. operations	$	3,190	$	1,978	$	1,990
Non-U.S. operations		82,019		50,058		25,905
Income before income taxes	$	85,209	$	52,036	$	27,895

Schedule of Income Tax Provision

Income tax provision consisted of the following for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
Current:
U.S. federal tax	$	5,273		$	3,135		$	1,738
U.S. state taxes		541			93			23
Non-U.S. foreign taxes		1,874			1,348			1,058
		7,688			4,576			2,819
Deferred:
U.S. federal tax		1,050			(3,208	)		(952	)
U.S. state taxes		—			—			341
Non-U.S. foreign taxes		(37	)		97			33
		1,013			(3,111	)		(578	)
Provision for income taxes	$	8,701		$	1,465		$	2,241

Schedule of Income Tax Provision Differed from Amounts Computed by Applying U.S. Federal Income Tax Rate

Income tax provision differed from the amounts computed by applying the U.S. federal income tax rate of 34% to pretax income as a result of the following for the periods indicated:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
U.S. federal tax at statutory rate	$	28,971		$	17,692		$	9,484
U.S. state taxes		541			90			361
Non-U.S. foreign tax differential		(26,253	)		(15,644	)		(7,674	)
Stock-based compensation		2,896			1,601			927
U.S. R&D credit		(3,517	)		(2,298	)		(858	)
Valuation allowance		6,090			—			—
Other		(27	)		24			1
Provision for income taxes	$	8,701		$	1,465		$	2,241

Schedule of Deferred Tax Assets and Liabilities

Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities at January 31, 2016 and 2015 were as follows:

	As of January 31,
	2016			2015
	(in thousands)
Deferred tax assets:
Federal and state credits	$	11,852		$	6,465
Expenses not currently deductible		2,331			1,590
Stock-based compensation		2,503			2,044
Gross deferred tax assets		16,686			10,099
Valuation allowance		(12,072	)		(3,996	)
Total deferred tax assets	$	4,614		$	6,103
Deferred tax liabilities
Property and equipment		(1,378	)		(199	)
Foreign deferred		(33	)		(70	)
Net deferred tax assets	$	3,203		$	5,834

Summary of Tax Valuation Allowance

Tax valuation allowance for the periods indicated below were as follows:

							Deductions
					Additions		Charged to
	Balance at		Additional		Charged to		Expenses		Balance at
	Beginning of		Charged to		Other		or Other		End of
	Period		Expenses		Account		Accounts		Period
	(in thousands)
Tax Valuation Allowance
Year ended January 31, 2016	$	3,996		8,076		—		—	$	12,072
Year ended January 31, 2015	$	2,302		1,694		—		—	$	3,996
Year ended January 31, 2014	$	1,243		1,059		—		—	$	2,302

Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

The following table sets forth a reconciliation of the beginning and ending amount of unrecognized tax benefits:

	Year Ended January 31,
	2016			2015			2014
	(in thousands)
Beginning balance:	$	4,671		$	3,583		$	3,018
Additions based on tax positions related to the current year		17,169			1,284			539
Additions for tax positions of prior years		8,810			324			62
Reductions for tax positions in prior years		(37	)		—			—
Settlements for prior periods		—			(43	)		—
Lapse of applicable statute of limitations		(402	)		(477	)		(36	)
Ending balance:	$	30,211		$	4,671		$	3,583

Commitments and Contingencies (Tables)

12 Months Ended

Jan. 31, 2016

Commitments And Contingencies Disclosure [Abstract]

Future Annual Minimum Lease Payments

Future annual minimum payments under these operating agreements with initial lease terms in excess of one year are as follows

	As of
	January 31, 2016
Fiscal Year	(in thousands)
2017	$	5,844
2018		2,282
2019		1,714
2020		1,532
2021		515
Total future annual minimum lease payments	$	11,887

Segment Reporting (Tables)

12 Months Ended

Jan. 31, 2016

Segment Reporting [Abstract]

Company's Revenue by Geographic Region

The following table sets forth the Company’s revenue by geographic region for the periods indicated:

	Year Ended January 31,
	2016		2015		2014
	(in thousands)
Hong Kong	$	284,722	$	196,372	$	135,382
Asia Pacific		3,930		2,358		2,809
United States		8,855		6,677		7,128
North America other than Unites States		9,953		6,076		4,594
Europe		8,913		6,795		7,695
Total revenue	$	316,373	$	218,278	$	157,608

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Estimated useful life	3 years	3 years	3 years
Capitalized internal-use software	$ 1,700,000
Impairment of long-lived assets	0
Goodwill impairment	0
Impairment losses on investment	$ 0
Expected dividend yield	0.00%	0.00%	0.00%

Financial Instruments and Fair Value - Schedule of Available-for-Sale Securities at Fair Value (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 40,374	$ 40,131
Unrealized Gains	11	9
Unrealized Losses	(18)	(10)
Fair Value	40,367	40,130
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	530	2,427
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	530	2,427
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,598	1,497
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	2,598	1,497
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,342	32,356
Unrealized Gains	7	9
Unrealized Losses	(9)	(10)
Fair Value	21,340	32,355
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,586	3,851
Unrealized Gains	0	0
Unrealized Losses	(1)	0
Fair Value	4,585	$ 3,851
U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,274
Unrealized Gains	4
Unrealized Losses	(6)
Fair Value	9,272
Agency bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,044
Unrealized Gains	0
Unrealized Losses	(2)
Fair Value	$ 2,042

Financial Instruments and Fair Value - Schedule of Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	$ 40,367	$ 40,130
Included in cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	530	2,427
Included in marketable securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	$ 39,837	$ 37,703

Financial Instruments and Fair Value - Summary of Contractual Maturities of Investments (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due within one year	$ 33,449	$ 37,559
Due within one to two years	6,918	2,571
Total cash equivalents and marketable securities	$ 40,367	$ 40,130

Inventories - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Inventory Disclosure [Abstract]
Work-in-progress	$ 9,474	$ 13,805
Finished goods	8,693	7,888
Total	$ 18,167	$ 21,693

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 11,301	$ 9,279
Less: accumulated depreciation and amortization	(7,853)	(6,204)
Total property and equipment, net	3,448	3,075
Computer equipment and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,421	5,310
Machinery and equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,706	2,234
Furniture and fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	492	456
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,429	1,215
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 253	$ 64

Acquisition - Additional Information (Detail) - USD ($) $ in Thousands		12 Months Ended
	Jun. 25, 2015	Jan. 31, 2016	Jan. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 26,601	$ 0
Vis Lab S R L
Business Acquisition [Line Items]
Business acquisition date	Jun. 25, 2015
Cash paid for business acquisition	$ 30,000	30,000
Intangible assets acquired	4,100	4,100
Goodwill	25,300	25,300
Net assets acquired	$ 600	$ 600

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)		12 Months Ended
	Jun. 25, 2015	Jan. 31, 2016	Jan. 31, 2015
Finite Lived Intangible Assets [Line Items]
Goodwill		$ 26,601,000	$ 0
Impairment of goodwill or intangible assets		0
IPR&D
Finite Lived Intangible Assets [Line Items]
Amortization of intangible asset		0
Vis Lab S R L
Finite Lived Intangible Assets [Line Items]
Business acquisition date	Jun. 25, 2015
Goodwill	$ 25,300,000	25,300,000
Intangible assets acquired	4,100,000	4,100,000
Deferred tax liabilities, intangible assets	$ 1,300,000	$ 1,300,000

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Payables And Accruals [Abstract]
Accrued employee compensation	$ 14,512	$ 11,318
Accrued warranty	234	203
Accrued rebates	824	254
Accrued product development costs	6,339	5,004
Other accrued liabilities	1,869	1,920
Total accrued liabilities	$ 23,778	$ 18,699

Deferred Revenue and Deferred Cost - Schedule of Deferred Revenue and Related Cost (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Deferred Revenue Disclosure [Abstract]
Deferred revenue on product shipments	$ 12,201	$ 4,663
Deferred revenue from licenses & services	1,653	1,610
Deferred cost of revenue on product shipments	(3,777)	(1,168)
Total deferred revenue, net	$ 10,077	$ 5,105

Other Long-Term Liabilities - Schedule of Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Other Liabilities Disclosure [Abstract]
Unrecognized tax benefits, including interest	$ 10,917	$ 1,391
Deferred tax liabilities, non-current	1,423
Other long-term liabilities	2	2
Total other long-term liabilities	$ 12,342	$ 1,393

Capital Stock - Additional Information (Detail) - $ / shares	Jan. 31, 2016	Jan. 31, 2015
Equity [Abstract]
Preference shares, shares authorized	20,000,000	20,000,000
Preference shares, par value	$ 0.00045	$ 0.00045
Preference shares, shares issued	0	0
Preference shares, shares outstanding	0	0
Ordinary shares, shares authorized	200,000,000	200,000,000

Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance (Detail) - shares	Jan. 31, 2016	Jan. 31, 2015
Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	5,027,475	5,055,845
Employee stock purchase plan awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	974,273	667,990

Employee Benefits and Stock-based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Feb. 02, 2015	Feb. 02, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Closing price of ordinary shares			$ 39.68
2012 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Voting power of all classes of company's shares			10.00%
Additional ordinary shares reserved for issuance	1,387,689	1,297,555
2012 Equity Incentive Plan [Member] \| Scenario, plan automatically increased by the lessor of [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in ordinary shares for available for future issuance	3,500,000	3,500,000
Annual shares increase for future issuance by percentage under 2012 equity incentive plan	4.50%	4.50%
2012 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of ordinary shares, percentage			85.00%	85.00%	85.00%
Additional ordinary shares reserved for issuance	385,469	359,356
Percentage of salary contribution by employees			15.00%
2012 Employee Stock Purchase Plan [Member] \| Scenario, plan automatically increased by the lessor of [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in ordinary shares for available for future issuance	1,500,000	1,500,000
Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan	1.25%	1.25%
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, stock options			$ 11.4
Weighted average recognition period			2 years 5 months 19 days
Stock options [Member] \| 2012 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option's term of up to 10 years from grant date			10 years	10 years	10 years
Vesting schedule			Vest 25% on the first anniversary service date of the grant and remainder vest ratably over the following 36 months.
Stock options [Member] \| Incentive stock options granted to 10% ownership [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of ordinary shares, percentage			110.00%
Stock options [Member] \| Non statutory stock options and incentive stock options granted to less than 10% ownership [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of ordinary shares, percentage			100.00%
Restricted Stock and Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, granted			1,314,387	1,111,204	1,265,472
Aggregate intrinsic value of unvested restricted stock and restricted stock units			$ 99.0
Restricted Stock and Restricted Stock Units [Member] \| 2012 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting schedule			1/4th of the shares on the first anniversary service date of the grant and 1/16th of the shares vest every 3 months thereafter, so as to be 100% vested on the fourth anniversary of the vesting commencement date.
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, granted			268,394
Weighted average recognition period			3 years 3 months 26 days
Total unrecognized compensation cost, restricted stock awards			$ 12.8
Restricted stock units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average recognition period			3 years 1 month 24 days
Total unrecognized compensation cost, restricted stock units			$ 96.8

Employee Benefits and Stock-based Compensation - Classification of Stock-based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Stock-based compensation:
Total stock-based compensation	$ 31,094	$ 15,692	$ 8,535
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	657	343	178
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	19,082	8,654	4,887
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 11,355	$ 6,695	$ 3,470

Employee Benefits and Stock-based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value (Detail)	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	57.00%	64.00%	65.00%
Risk-free interest rate	1.74%	1.93%	1.55%
Expected term (years)	6 years 29 days	6 years 4 days	6 years 22 days
Dividend yield	0.00%	0.00%	0.00%
Employee stock purchase plan awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	63.00%	49.00%	52.00%
Risk-free interest rate	0.21%	0.07%	0.04%
Expected term (years)	6 months	6 months	6 months
Dividend yield	0.00%	0.00%	0.00%

Employee Benefits and Stock-based Compensation - Stock Option Activities (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding	2,281,909	3,358,706	4,344,535
Shares, Granted	179,700	428,781	255,520
Shares, Exercised	(567,888)	(1,456,944)	(1,160,286)
Shares, Forfeited	(40,331)	(48,634)	(81,063)
Shares, Outstanding	1,853,390	2,281,909	3,358,706
Shares, Exercisable	1,363,880
Shares, Vested and expected to vest	1,822,252
Weighted-Average Exercise Price, Outstanding	$ 13.00	$ 6.92	$ 6.07
Weighted-Average Exercise Price, Granted	71.36	36.33	18.14
Weighted-Average Exercise Price, Exercised	9.11	5.84	5.96
Weighted-Average Exercise Price, Forfeited	35.65	13.38	10.34
Weighted-Average Exercise Price, Outstanding	19.36	13.00	6.92
Weighted-Average Exercise Price, Exercisable	10.23
Weighted-Average Exercise Price, Vested and expected to vest	18.84
Weighted-Average Grant-date Fair Value, Granted	$ 38.81	$ 21.37	$ 10.85
Total Intrinsic Value of options Exercised	$ 37,603	$ 46,427	$ 18,217
Weighted-Average Remaining Contractual Term, Outstanding	5 years 10 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 11 months 5 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	5 years 10 months 2 days
Aggregate Intrinsic Value, Outstanding	$ 43,396
Aggregate Intrinsic Value, Exercisable	40,341
Aggregate Intrinsic Value, Vested and expected to vest	$ 43,285

Employee Benefits and Stock-based Compensation - Restricted Stock and Restricted Stock Units Activities (Detail) - Restricted stock and restricted stock units [Member] - $ / shares	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested, beginning balance	1,980,448	1,410,089	339,217
Shares, Granted	1,314,387	1,111,204	1,265,472
Shares, Vested	(769,779)	(484,296)	(174,888)
Shares, Forfeited	(29,568)	(56,549)	(19,712)
Shares, Unvested, ending balance	2,495,488	1,980,448	1,410,089
Weighted-Average Grant-Date Fair Value, Unvested, beginning balance	$ 26.82	$ 14.02	$ 9.99
Weighted-Average Grant-Date Fair Value, Granted	66.14	38.60	14.78
Weighted-Average Grant-Date Fair Value, Vested	27.82	17.39	11.91
Weighted-Average Grant-Date Fair Value, Forfeited	42.11	19.93	11.97
Weighted-Average Grant-Date Fair Value, Unvested, ending balance	$ 47.04	$ 26.82	$ 14.02

Net Income Per Ordinary Share - Computation of Basic and Diluted Net Income Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Numerator:
Net income	$ 76,508	$ 50,571	$ 25,654
Less: amount allocable to unvested early exercised options	0	(11)	(31)
Net income allocable to ordinary shareholders - basic	76,508	50,560	25,623
Undistributed earnings reallocated to ordinary shareholders	0	1	2
Net income allocable to ordinary shareholders - diluted	$ 76,508	$ 50,561	$ 25,625
Denominator:
Weighted-average ordinary shares outstanding	31,633,992	29,749,354	27,713,998
Less: weighted-average unvested early exercised options subject to repurchase	(56)	(6,701)	(33,220)
Weighted-average ordinary shares - basic	31,633,936	29,742,653	27,680,778
Effect of potentially dilutive securities:
Employee stock options	1,245,341	1,818,401	2,034,500
Restricted stock and restricted stock units	865,863	704,788	316,350
Employee stock purchase plan	10,569	12,285	138,461
Warrants to purchase ordinary shares	0	0	2,474
Weighted-average ordinary shares - diluted	33,755,709	32,278,127	30,172,563
Net income per ordinary share:
Basic	$ 2.42	$ 1.70	$ 0.93
Diluted	$ 2.27	$ 1.57	$ 0.85

Net Income Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Net Income Per Ordinary Share (Detail) - shares	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	283,081	428,027	229,252
Options to purchase ordinary shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	109,958	217,514	183,859
Restricted stock and restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	163,994	167,702	1,576
Employee stock purchase plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	9,073	36,110	10,597
Early exercised options subject to repurchase [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	56	6,701	33,220

Income Taxes - Summary of Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Results Of Operations Income Before Income Taxes [Abstract]
U.S. operations	$ 3,190	$ 1,978	$ 1,990
Non-U.S. operations	82,019	50,058	25,905
Income before income taxes	$ 85,209	$ 52,036	$ 27,895

Income Taxes - Schedule of Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Current:
U.S. federal tax	$ 5,273	$ 3,135	$ 1,738
U.S. state taxes	541	93	23
Non-U.S. foreign taxes	1,874	1,348	1,058
Current income tax provision	7,688	4,576	2,819
Deferred:
U.S. federal tax	1,050	(3,208)	(952)
U.S. state taxes	0	0	341
Non-U.S. foreign taxes	(37)	97	33
Deferred income tax provision	1,013	(3,111)	(578)
Provision for income taxes	$ 8,701	$ 1,465	$ 2,241

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Income Taxes [Line Items]
U.S. federal income tax rate	34.00%	34.00%	34.00%
Deferred tax liabilities, not recognized	$ 3,900,000
Cumulative undistributed earnings of foreign subsidiaries	32,800,000
Gross deferred tax assets, net of deferred tax liabilities before valuation allowance	15,300,000	$ 9,800,000
Valuation allowance	12,072,000	3,996,000
Unrecognized tax benefits	30,211,000	4,671,000	$ 3,583,000	$ 3,018,000
Unrecognized tax benefits that would impact effective tax rate	6,300,000
Income tax liabilities considered as other long term liabilities	10,800,000	1,200,000
Interest expense and penalties related to uncertain tax positions	6,000	7,000	$ 37,000
Noncurrent liabilities related to interest and penalties for uncertain tax positions	166,000	$ 160,000
Long term income taxes payable, including estimated interest and penalties	10,900,000
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryovers	$ 33,100,000
Net operating loss carryovers begin to expire in fiscal year	2035
Research and development credit carryforwards	$ 6,100,000
Federal credits begin to expire in fiscal year	2034
California state [Member]
Income Taxes [Line Items]
Net operating loss carryovers	$ 7,400,000
Net operating loss carryovers begin to expire in fiscal year	2035
Research and development credit carryforwards	$ 8,700,000

Income Taxes - Schedule of Income Tax Provision Differed from Amounts Computed by Applying U.S. Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal tax at statutory rate	$ 28,971	$ 17,692	$ 9,484
U.S. state taxes	541	90	361
Non-U.S. foreign tax differential	(26,253)	(15,644)	(7,674)
Stock-based compensation	2,896	1,601	927
U.S. R&D credit	(3,517)	(2,298)	(858)
Valuation allowance	6,090	0	0
Other	(27)	24	1
Provision for income taxes	$ 8,701	$ 1,465	$ 2,241

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Deferred tax assets:
Federal and state credits	$ 11,852	$ 6,465
Expenses not currently deductible	2,331	1,590
Stock-based compensation	2,503	2,044
Gross deferred tax assets	16,686	10,099
Valuation allowance	(12,072)	(3,996)
Total deferred tax assets	4,614	6,103
Deferred tax liabilities
Property and equipment	(1,378)	(199)
Foreign deferred	(33)	(70)
Net deferred tax assets	$ 3,203	$ 5,834

Income Taxes - Summary of Tax Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 3,996
Balance at End of Period	12,072	$ 3,996
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	3,996	2,302	$ 1,243
Additional Charged to Expenses	8,076	1,694	1,059
Additions Charged to Other Account	0	0	0
Deductions Charged to Expenses or Other Accounts	0	0	0
Balance at End of Period	$ 12,072	$ 3,996	$ 2,302

Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Income Tax Disclosure [Abstract]
Beginning balance	$ 4,671	$ 3,583	$ 3,018
Additions based on tax positions related to the current year	17,169	1,284	539
Additions for tax positions of prior years	8,810	324	62
Reductions for tax positions in prior years	(37)
Settlements for prior periods	0	(43)
Lapse of applicable statute of limitations	(402)	(477)	(36)
Ending balance	$ 30,211	$ 4,671	$ 3,583

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Loss Contingencies [Line Items]
Net operating lease expenses	$ 6,800,000	$ 5,800,000	$ 5,000,000
Total manufacturing purchase commitments	19,700,000	27,500,000
Indemnification agreement [Member]
Loss Contingencies [Line Items]
Payments under indemnification obligations	0	0
Liabilities recorded under indemnification obligations	$ 0	$ 0

Commitments and Contingencies - Future Annual Minimum Lease Payments (Detail) $ in Thousands	Jan. 31, 2016 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2017	$ 5,844
2018	2,282
2019	1,714
2020	1,532
2021	515
Total future annual minimum lease payments	$ 11,887

Segment Reporting - Additional Information (Detail) $ in Thousands	12 Months Ended
	Jan. 31, 2016 USD ($) Segment	Jan. 31, 2015 USD ($)	Jan. 31, 2014
Concentration Risk [Line Items]
Number of reportable segment \| Segment	1
Long-lived assets	$ 3,448	$ 3,075
Accounts receivable	39,408	40,180
Wintech And Chicony [Member]
Concentration Risk [Line Items]
Accounts receivable	$ 32,500	$ 36,200
Wintech And Chicony [Member] \| Sales revenue, net [Member] \| Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue	88.00%	89.00%	85.00%
Wintech And Chicony [Member] \| Sales revenue, net [Member] \| Customer concentration risk [Member] \| Minimum [Member]
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	10.00%	10.00%	10.00%
Wintech And Chicony [Member] \| Accounts receivable [Member] \| Credit concentration risk [Member] \| Minimum [Member]
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	10.00%	10.00%	10.00%
United States [Member]
Concentration Risk [Line Items]
Long-lived assets	$ 1,600	$ 1,800
Asia Pacific [Member]
Concentration Risk [Line Items]
Long-lived assets	$ 1,500	$ 1,000

Segment Reporting - Company's Revenue by Geographic Region (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Revenue from External Customer [Line Items]
Total revenue	$ 316,373	$ 218,278	$ 157,608
Hong Kong [Member]
Revenue from External Customer [Line Items]
Total revenue	284,722	196,372	135,382
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	3,930	2,358	2,809
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	8,855	6,677	7,128
North America other than Unites States [Member]
Revenue from External Customer [Line Items]
Total revenue	9,953	6,076	4,594
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 8,913	$ 6,795	$ 7,695

Related-Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended			33 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2017	Jan. 31, 2013
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%
Other Entity [Member]
Related Party Transaction [Line Items]
Payment for license fees	$ 2.8	$ 2.3	$ 1.7
License expenses included in research and development expense	2.7	1.9	1.7
Other Entity [Member] \| Scenario, Forecast [Member]
Related Party Transaction [Line Items]
Commitment to make license payment				$ 7.5
Investor [Member]
Related Party Transaction [Line Items]
Percentage of investor own voting stock					4.60%
Recognized revenue from related party	210.6	125.1	$ 88.7
Account receivables from related party	$ 20.6	$ 12.1

Financial Instruments and Fair Value - Schedule of Fair Value of Financial Instruments Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	$ 40,367	$ 40,130
Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	530	2,427
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	2,598	1,497
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	21,340	32,355
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	4,585	3,851
U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	9,272
Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	2,042
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	530	2,427
Level 1 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	530	2,427
Level 1 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 1 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 1 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 1 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0
Level 1 [Member] \| Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	39,837	37,703
Level 2 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 2 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	2,598	1,497
Level 2 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	21,340	32,355
Level 2 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	4,585	3,851
Level 2 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	9,272
Level 2 [Member] \| Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	2,042
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 3 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 3 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 3 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	0
Level 3 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0	$ 0
Level 3 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	0
Level 3 [Member] \| Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities	$ 0