Document and Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jul. 31, 2013
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 31, 2014
Document Fiscal Year Focus	2014
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	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding	28,748,513
Entity Public Float		$ 344

Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Current assets:
Cash	$ 143,394	$ 100,494
Accounts receivable, net	18,837	20,153
Inventories	10,452	8,918
Restricted cash	3	3
Deferred tax assets, current	1,599	1,220
Prepaid expenses and other current assets	2,951	2,360
Total current assets	177,236	133,148
Property and equipment, net	3,018	2,536
Deferred tax assets, non-current	1,134	938
Other assets	1,919	1,981
Total assets	183,307	138,603
Current liabilities:
Accounts payable	8,321	7,051
Accrued liabilities	11,705	14,042
Income taxes payable	545	286
Deferred revenue, current	4,831	3,451
Total current liabilities	25,402	24,830
Other long-term liabilities	1,544	1,441
Total liabilities	26,946	26,271
Commitments and contingencies (Note 10)
Shareholders' equity:
Preference shares, $0.00045 par value per share, 20,000,000 shares authorized and no shares issued and outstanding at January 31, 2014 and January 31, 2013, respectively
Ordinary shares, $0.00045 par value per share, 200,000,000 shares authorized at January 31, 2014 and January 31, 2013, respectively; 28,748,513 shares issued and outstanding at January 31, 2014; 27,035,074 shares issued and outstanding at January 31, 2013	13	12
Additional paid-in capital	110,285	91,911
Retained earnings	46,063	20,409
Total shareholders' equity	156,361	112,332
Total liabilities and shareholders' equity	$ 183,307	$ 138,603

Consolidated Balance Sheets (Parenthetical) (USD $)	Jan. 31, 2014	Jan. 31, 2013
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	28,748,513	27,035,074
Ordinary shares, shares outstanding	28,748,513	27,035,074

Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Statement [Abstract]
Revenue	$ 157,608	$ 121,066	$ 97,257
Cost of revenue	57,761	40,405	32,458
Gross profit	99,847	80,661	64,799
Operating expenses:
Research and development	48,777	42,829	37,618
Selling, general and administrative	23,153	17,926	15,926
Total operating expenses	71,930	60,755	53,544
Income from operations	27,917	19,906	11,255
Other income (loss), net	(22)	136	(90)
Income before income taxes	27,895	20,042	11,165
Provision for income taxes	2,241	1,854	1,344
Net income	$ 25,654	$ 18,188	$ 9,821
Net income per share attributable to ordinary shareholders:
Basic	$ 0.93	$ 0.64	$ 0.32
Diluted	$ 0.85	$ 0.60	$ 0.30
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	27,680,778	13,511,646	7,961,944
Diluted	30,172,563	15,016,986	9,469,820

Consolidated Statements of Redeemable Convertible Preference Shares and Shareholders' Equity (Deficit) (USD $) In Thousands, except Share data	Total	Outstanding Ordinary Shares [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Redeemable Convertible Preference Shares [Member]
Beginning Balance, Amount at Jan. 31, 2011	$ (1,104)	$ 3	$ 6,493	$ (7,600)	$ 39,273
Beginning Balance, Shares at Jan. 31, 2011		7,845,240			12,268,131
Issuance of preference shares, Amount					11,627
Issuance of preference shares, Shares					1,047,596
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Amount	824		824
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Shares	454,053	454,053
Vesting of early exercised stock options	394		394
Stock-based compensation expense related to stock awards granted to employees and consultants	3,616		3,616
Net excess income tax benefit associated with stock-based compensation	125		125
Repurchase of ordinary shares, Amount	(7,227)		(7,227)
Repurchase of ordinary shares, Shares		(698,424)
Net income	9,821			9,821
Ending Balance, Amount at Jan. 31, 2012	6,449	3	4,225	2,221	50,900
Ending Balance, Shares at Jan. 31, 2012		7,600,869			13,315,727
Conversion of redeemable convertible preference shares to ordinary shares, Amount	50,900	6	50,894		(50,900)
Conversion of redeemable convertible preference shares to ordinary shares, Shares		13,315,727			(13,315,727)
Issuance of shares in connection with initial public offering, net of issuance cost, Amount	30,415	3	30,412
Issuance of shares in connection with initial public offering, net of issuance cost, Shares		5,804,651
Conversion of preference share warrants to ordinary share warrants	110		110
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Amount	950		950
Exercise of stock options, dollar amounts net of unvested stock options exercised early, Shares	313,827	313,827
Vesting of early exercised stock options	314		314
Stock-based compensation expense related to stock awards granted to employees and consultants	4,999		4,999
Net excess income tax benefit associated with stock-based compensation	7		7
Net income	18,188			18,188
Ending Balance, Amount at Jan. 31, 2013	112,332	12	91,911	20,409
Ending Balance, Shares at Jan. 31, 2013	27,035,074	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	1,160,286
Vesting of early exercised stock options	143		143
Vesting of restricted stock units
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
Net 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	28,748,513

Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Cash flows from operating activities:
Net income	$ 25,654	$ 18,188	$ 9,821
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	1,096	737	596
Loss on disposal of long-lived assets	13	4	23
Amortization of other intangible assets		270	540
Stock-based compensation	8,535	4,999	3,616
Net excess income tax benefits associated with stock-based compensation	(903)	7	(125)
Change in value of warrants		(149)	103
Changes in operating assets and liabilities:
Accounts receivable	1,316	(10,668)	(656)
Inventories	(1,534)	(2,132)	624
Prepaid expenses and other current assets	(375)	(1,134)	(511)
Deferred tax assets	(433)	(871)	(149)
Other assets	63	(443)	(113)
Accounts payable	1,270	45	112
Accrued liabilities	(2,539)	6,656	980
Income taxes payable	807	(244)	244
Deferred revenue	1,380	(4,751)	(2,419)
Net cash provided by operating activities	34,350	10,514	12,686
Cash flows from investing activities:
Restricted Cash		514	(274)
Investment in a private company			102
Net proceeds from disposal of fixed assets	13
Purchase of property and equipment	(1,701)	(1,528)	(682)
Purchase of intangible assets			(630)
Net cash used in investing activities	(1,688)	(1,014)	(1,484)
Cash flows from financing activities:
Net proceeds from issuance of preference shares			11,627
Repurchase of ordinary shares, at cost			(7,228)
Proceeds from exercise of stock options, warrants, and employee stock purchase plan, net of repurchase of stock options	9,360	1,610	1,322
Payment for initial public offering cost	(25)	(1,950)
Proceeds from initial public offering, net of underwriting discounts and commissions		32,390
Net excess income tax benefits associated with stock-based compensation	903		125
Net cash provided by financing activities	10,238	32,050	5,846
Net increase in cash and cash equivalents	42,900	41,550	17,048
Cash and cash equivalents at beginning of period	100,494	58,944	41,896
Cash and cash equivalents at end of period	143,394	100,494	58,944
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,766	3,402	854
Supplemental disclosure of noncash investing activities:
Increase in accrued liabilities related to non-monetary assets purchases	24	122	59
Supplemental disclosure of noncash financing activities:
Increase in accrued liabilities related to non-monetary financing activities		25
Conversion of redeemable convertible preference shares to ordinary shares		50,900
Conversion of redeemable convertible preference share warrants to ordinary share warrants		$ 110

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Jan. 31, 2014
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. In October 2012, in connection with its initial public offering, or IPO, the Company completed the sale of 6,000,000 ordinary shares inclusive of 1,095,349 shares sold by certain shareholders of the Company. In November 2012, a total of 900,000 ordinary shares were sold to the Company’s IPO underwriters in connection with their exercise of the over-allotment option. The public offering price of the shares sold in this offering was $6.00 per share. The total net proceeds from the offering to the Company were approximately $30.4 million after deducting underwriting discounts and commissions and other offering expenses. Upon the completion of the IPO, all 13,315,727 outstanding redeemable convertible preference shares converted into ordinary shares on a one-to-one basis and all outstanding warrants to purchase redeemable convertible preference shares converted into warrants to purchase ordinary shares. *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 collectability of accounts receivable; (ii) write down for excess and obsolete inventories; (iii) the estimated useful lives of long-lived assets; (iv) impairment of long-lived assets and financial instruments; (v) warranty obligations; (vi) the valuation of stock-based compensation and equity instruments; (vii) the probability of performance objectives achievement; (viii) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (ix) 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 all of Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationship with these two customers 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 11 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 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 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 accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature. *Cash and Cash Equivalents* The Company considers all highly liquid investments with maturities of less than three months at the time of purchase to be cash equivalents. Investments with maturities at the time of acquisition greater than three months but less than one year are classified as short-term investments and considered as available-for-sale in current operations. There were no cash equivalents and short-term investments as of January 31, 2014 and 2013, respectively. *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 write-offs of accounts receivable for fiscal years 2014, 2013 and 2012, respectively. There was no allowance for doubtful accounts recorded as of January 31, 2014 and 2013, 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 has been established and, accordingly, any associated reserve is not reversed until the inventory sold or scrapped. There has been no material inventory loss to date to be recognized. *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, 2014, the Company has capitalized approximately $1.1 million of internal-use software and has been recorded in property and equipment, net on the consolidated balance sheets. *Impairment of Long-Lived Assets* The Company records long-lived assets at cost and evaluates them for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. 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. When the sum of the expected future undiscounted cash flows expected to be generated by the related asset group is less than its carrying amount, an impairment loss would be recognized. Should impairment exist, the impairment loss would be measured based on the excess of the carrying amount of the asset over the asset’s estimated fair value. 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, 2014. *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, the Company has not recognized any impairment losses related to this investment. *Revenue Recognition* The Company generates revenue from the sale 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 right 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 sells a limited amount of software under perpetual licenses that include post-contract customer support, or PCS. The Company does not have evidence of fair value for the PCS and, accordingly, license revenue is recognized ratably over the estimated supporting period in accordance with ASC 985, Software Revenue Recognition. The Company also enters into development agreements with certain customers. Revenue is deferred for any amounts billed prior to delivery of development services. However, if the Company retains the intellectual property generated from these development agreements, receipts and costs related to these arrangements are included in research and development expense. The revenue from those licenses and services were not material for the years ended January 31, 2014, 2013 and 2012, 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 have not been material to date. *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 have not been material to date. *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 estimates the fair value of restricted stock units, or RSUs, 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. Prior to the initial public offering, or IPO, the Company engaged an independent appraiser to assist in the valuation of its ordinary share price. The board of directors directed these regular valuations and had input into determining the relevant objective and subjective factors accounted for and relevant approaches in each valuation. After the IPO, the exercise price of stock option awards is determined by the closing price of the Company’s ordinary shares traded on The NASDAQ Global Market on the grant 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 Employee Stock Purchase Plan, or ESPP, upon release of vested restricted stock units, upon conversion of its redeemable convertible preference shares and upon exercise of warrants. 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* There are no differences between comprehensive income as defined by ASC 220, Comprehensive Income, and net income as reported in the Company’s consolidated statements of operations. *Recent Accounting Pronouncements* In February 2013, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“AOCI”). This new guidance requires that the Company present either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, the Company would instead cross reference to the related footnote for additional information. This guidance only impacts disclosures within the Company’s consolidated financial statements and notes to the consolidated financial statements and does not result in a change to the accounting treatment of AOCI. This new guidance became effective prospectively for fiscal years, and interim periods with those years, beginning after December 15, 2012. The Company adopted this guidance starting from the first quarter of fiscal year 2014 and the adoption did not have an impact on its financial position, results of operations or disclosures. In July 2013, the FASB issued ASU No. 2013-11, Income Taxes (Topic 740), Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss ,or a Tax Credit Carryforward Exists. The new guidance requires the netting of unrecognized tax benefits (“UTBs”) against a deferred tax asset for a loss or other carryforward that would apply in settlement of the uncertain tax positions. Under the new standard, UTBs will be netted against all available same-jurisdiction loss or other tax carryforwards that would be utilized, rather than only against carryforwards that are created by the UTBs. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013 and should be applied prospectively to all unrecognized tax benefits that exist at the effective date. Early adoption and retrospective application are permitted. The Company has not yet adopted this guidance but does not expect the adoption of this guidance to have a significant impact on its financial position, results of operations, statement of cash flows or disclosures.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

+ References+ Details

Inventories

12 Months Ended

Jan. 31, 2014

Inventory Disclosure [Abstract]

Inventories

2. Inventories

Inventories at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014		2013
	(in thousands)
Work-in-progress	$	5,119	$	3,012
Finished goods		5,333		5,906

Total	$	10,452	$	8,918

- Definition

The entire disclosure for inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income.

+ References+ Details

Property and Equipment, Net

12 Months Ended

Jan. 31, 2014

Property Plant And Equipment [Abstract]

Property and Equipment, Net

3. Property and Equipment, net

Depreciation expense was approximately $1.1 million, $0.7 million and $0.6 million for the years ended January 31, 2014, 2013 and 2012, respectively. Property and equipment at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014			2013
	(in thousands)
Computer equipment and software	$	4,521		$	2,810
Machinery and equipment		2,114			2,050
Furniture and fixtures		411			397
Leasehold improvements		1,198			642
Construction in progress		—			827

		8,244			6,726

Less: accumulated depreciation and amortization		(5,226	)		(4,190	)

Total property and equipment, net	$	3,018		$	2,536

In March 2013, the Company entered into a lease agreement of approximately 35,000 square feet for its new headquarters located in Santa Clara, California with an initial five-year term. Pursuant to the lease agreement, the Company agreed to pay certain construction costs. As of January 31, 2014, the Company had capitalized approximately $0.7 million of leasehold improvement as a result of the construction, which will be depreciated over the term of the lease.

In August 2012, the Company began implementation of its enterprise resources planning (“ERP”) system. As of January 31, 2014, the Company capitalized approximately $1.1 million of internal-use software related to the ERP implementation project and amortized over an estimated economic useful life of three years under a straight-line method.

- Definition

The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures.

+ References+ Details

Accrued Liabilities

12 Months Ended

Jan. 31, 2014

Payables And Accruals [Abstract]

Accrued Liabilities

4. Accrued Liabilities

Accrued liabilities at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014		2013
	(in thousands)
Accrued employee compensation	$	8,049	$	8,599
Refundable exercised unvested options		59		210
Accrued warranty		269		352
Accrued rebates		270		272
Accrued product development costs		1,904		2,875
Other accrued liabilities		1,154		1,734

Total accrued liabilities	$	11,705	$	14,042

Deferred Revenue, net

12 Months Ended

Jan. 31, 2014

Revenue Recognition [Abstract]

Deferred Revenue, net

5. Deferred Revenue, net

Deferred revenue and related cost at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014			2013
	(in thousands)
Deferred revenue on product shipments	$	5,174		$	3,827
Deferred revenue from licenses & services		1,023			485
Deferred cost of revenue on product shipments		(1,366	)		(861	)

Total deferred revenue, net	$	4,831		$	3,451

Capital Stock

12 Months Ended

Jan. 31, 2014

Text Block [Abstract]

Capital Stock

6. Capital Stock

Redeemable Convertible Preference shares

In January 2012, the Company completed the sale of Series D redeemable convertible preference shares, or Series D. A portion of the proceeds from the sale of Series D shares was used to repurchase ordinary shares under a repurchase program. A total of 1,047,596 shares of Series D preference were sold at a price of $11.25 per share, resulting in net proceeds of approximately $11.6 million. Upon the closing of the initial public offering, or IPO, all outstanding redeemable convertible preference shares, including the Series D shares, converted into ordinary shares on a one-to-one basis.

Redeemable convertible preference shares at January 31, 2012 consisted of the following:


	Par Value Per Share		Shares				Initial Liquidation Preference
Series	Par Value Per Share		Authorized		Outstanding		Initial Liquidation Preference
							(in thousands)
A	$	0.00045		5,611,111		5,611,107	$	10,100
B	$	0.00045		3,665,550		3,629,253		13,000
C	$	0.00045		3,027,777		3,027,771		16,350
D	$	0.00045		2,222,222		1,047,596		11,785

				14,526,660		13,315,727	$	51,235

Ordinary Share Repurchase Program

In January 2012, the Company completed an ordinary share repurchase program. Pursuant to the program, the Company offered to repurchase ordinary shares at a price of $10.35 per ordinary share, which approximated the then-current fair market value. A total of 698,424 ordinary shares were tendered by employees, former-employees and consultants for repurchase by the Company. The ordinary shares tendered for repurchase were originally acquired through the exercise of stock options prior to the shares being tendered. A total of approximately $7.2 million cash was paid to ordinary shareholders for the 698,424 shares repurchased. The cost of this repurchase program was reflected in additional paid-in capital in the consolidated statements of redeemable convertible preference shares and shareholders’ equity (deficit).

Initial Public Offering

In October 2012, in connection with its initial public offering, or IPO, the Company completed the sale of 6,000,000 ordinary shares inclusive of 1,095,349 shares sold by certain shareholders of the Company. In November 2012, a total of 900,000 ordinary shares were sold to the Company’s IPO underwriters in connection with their exercise of over-allotment option. The public offering price of the shares sold in this offering was $6.00 per share. The total net proceeds from the offering to the Company were approximately $30.4 million after deducting underwriting discounts and commissions and other offering expenses. Upon the completion of the IPO, all 13,315,727 outstanding redeemable convertible preference shares converted into ordinary shares on a one-to-one basis and all outstanding warrants to purchase redeemable convertible preference shares converted into warrants to purchase ordinary shares.

Preference shares

After completion of the 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, 2014 and 2013, respectively.

Warrants

In connection with a financing agreement in 2004, the Company issued warrants to purchase 36,292 redeemable convertible preference shares at an exercise price of $3.582 per share.

Prior to the closing of IPO, the Company utilized the Black-Scholes option pricing model to determine the fair value of the warrants, including the consideration of underlying ordinary share price, a risk-free interest rate, expected term and expected volatilities. Certain inputs used in the model were unobservable. As a result, the valuation of warrants is categorized as Level 3 in accordance with ASC 820, Fair Value Measurement. The warrants were revalued up to the closing of IPO and any change in fair value had been recorded in other income (loss).

Upon the completion of the IPO, the warrants to purchase redeemable convertible preference shares converted to warrants to purchase ordinary shares. As a result, $110,000 of aggregate fair market value was reclassified from liabilities to shareholders’ equity. As of January 31, 2014, the warrants were fully exercised and were no longer outstanding.

Ordinary shares

200,000,000 ordinary shares were authorized at January 31, 2014 and 2013, respectively. As of January 31, 2014 and 2013, the following ordinary shares were reserved for future issuance:


	As of January 31,
	2014		2013
Shares reserved for options and restricted stock units		5,699,530		5,818,126
Shares reserved for employee stock purchase plan		456,410		460,445
Shares reserved for warrants		—		36,292

Employee Benefits and Stock-based Compensation

12 Months Ended

Jan. 31, 2014

Postemployment Benefits [Abstract]

Employee Benefits and Stock-based Compensation

7. 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 board of directors adopted, and the shareholders approved, the 2004 Stock Plan, as amended, (the “2004 Plan”). The 2004 Plan was last amended on August 28, 2012. The 2004 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 board of directors adopted, and the shareholders approved, the 2012 Equity Incentive Plan, (the “EIP”). The EIP became effective on October 8, 2012. The 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 Plans have a term of up to 10 years from grant date. Options granted to new employees generally vest 25% on the first anniversary 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 units, or RSUs, granted to new employees generally vest as to 1/4th of the shares on the first anniversary date of the grant and 1/16th of the RSUs 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 RSUs shall not vest at all until the performance conditions are achieved and are subject to the RSU holder continuing to provide services to the Company through such vesting dates. The performance condition RSUs 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 EIP provides for annual increases in the number of shares available for issuance under the EIP on the first day of each fiscal year beginning with the 2014 fiscal year, by an amount equal to the least of 3,500,000 shares; or 4.5% of our outstanding ordinary shares as of the last day of our immediately preceding fiscal year; or such lesser amount, if any, as our board of directors may determine.

2012 Employee Stock Purchase Plan. The board of directors adopted, and the shareholders approved, the 2012 Employee Stock Purchase Plan, or ESPP, which became effective upon the completion of IPO. The ESPP permits eligible participants to purchase ordinary shares at a discount through contributions of up to 10% 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.

The ESPP provides for annual increases in the number of shares available for issuance under the ESPP on the first day of each fiscal year beginning with the 2014 fiscal year, equal to the least of 1,500,000 shares; or 1.25% of the outstanding shares of our ordinary shares on the first day of such fiscal year; or such other amount as may be determined by the administrator.

Early Exercise Rights. Certain employees have the rights to early exercise unvested options, subject to repurchase rights held by the Company at their original purchase price upon termination of employment until vested. As of January 31, 2014 and 2013, a total of 86,340 and 84,377 shares of unvested early exercised options were repurchased, respectively. There were 13,289 and 53,151 unvested shares subject to the Company’s repurchase rights as of January 31, 2014 and 2013, respectively.

Stock-based Compensation

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


	Year Ended January 31,
	2014		2013		2012
	(in thousands)
Stock-based compensation:
Cost of revenue	$	178	$	92	$	52
Research and development		4,887		2,942		1,821
Selling, general and administrative		3,470		1,965		1,743

Total stock-based compensation	$	8,535	$	4,999	$	3,616

As of January 31, 2014, total unrecognized compensation cost related to unvested stock options and unvested restricted stock units was $5.8 million and $17.0 million, respectively, and is expected to be recognized over a weighted-average period of 1.90 years and 2.99 years, respectively. As of January 31, 2013, total unrecognized compensation cost related to unvested stock options and unvested restricted stock units was $7.3 million and $2.4 million, respectively, and is expected to be recognized over a weighted-average period of 2.26 years and 1.77 years, respectively.

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,
	2014			2013			2012
Stock Options:
Volatility		65	%		66	%		65	%
Risk-free interest rate		1.55	%		0.91	%		1.64	%
Expected term (years)		6.06			6.05			6.05
Dividend yield		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		52	%		51	%		N/A
Risk-free interest rate		0.04	%		0.18	%		N/A
Expected term (years)		0.5			0.94			N/A
Dividend yield		0	%		0	%		N/A

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


	Option Outstanding
	Shares			Weighted- Average Exercise Price		Weighted- Average Grant-date Fair Value		Total Intrinsic Value of options Exercised (in thousands)		Weighted- Average Remaining Contactual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 31, 2011		3,814,782			4.35
Granted		1,207,564			8.82	$	5.24
Exercised		(454,053	)		2.91			$	2,682
Forfeited		(192,387	)		6.78

Outstanding at January 31, 2012		4,375,906			5.63
Granted		451,071			8.79	$	5.23
Exercised		(313,827	)		3.21			$	2,087
Forfeited		(168,615	)		7.22

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						6.24	$	84,334
Exercisable at January 31, 2014		2,529,324			5.57						5.62	$	66,919
Vested and expected to vest at January 31, 2014		3,318,394			6.86						6.22	$	83,532

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 $32.03 on January 31, 2014, 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 units activities for the periods indicated:


	Shares			Weighted- Average Grant-Date Fair Value
Unvested at January 31, 2012		—		$	—
Granted		345,171			9.99
Vested		—			—
Forfeited		(5,954	)		9.99

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

As of January 31, 2014, the aggregate intrinsic value of unvested restricted stock units was $45.2 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, 2014, 2013 and 2012, respectively.

Net Income Per Ordinary Share

12 Months Ended

Jan. 31, 2014

Earnings Per Share [Abstract]

Net Income Per Ordinary Share

8. 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,
	2014			2013			2012
	(in thousands, except share and per share data)
Numerator:
Net income	$	25,654		$	18,188		$	9,821
Less: amount allocable to preference shareholders		—			(9,517	)		(7,204	)
Less: amount allocable to unvested early exercised options		(31	)		(61	)		(51	)

Net income allocable to ordinary shareholders—basic	$	25,623		$	8,610		$	2,566

Undistributed earnings reallocated to ordinary shareholders		2			432			277

Net income allocable to ordinary shareholders—diluted	$	25,625		$	9,042		$	2,843

Denominator:
Weighted-average ordinary shares outstanding		27,713,998			13,599,273			8,118,834
Less: weighted-average unvested early exercised options subject to repurchase		(33,220	)		(87,627	)		(156,890	)

Weighted-average ordinary shares—basic		27,680,778			13,511,646			7,961,944

Effect of potentially dilutive securities:
Employee stock options		2,034,500			1,443,809			1,507,876
Restricted stock units		316,350			16,930			—
Employee stock purchase plan		138,461			27,230			—
Warrants to purchase ordinary shares		2,474			6,737			—
Over-allotment shares		—			10,634			—
Weighted-average ordinary shares—diluted		30,172,563			15,016,986			9,469,820

Net income per ordinary share:
Basic	$	0.93		$	0.64		$	0.32

Diluted	$	0.85		$	0.60		$	0.30

Earnings per share (EPS) of ordinary shares was calculated using the two-class method required for participating securities. Prior to the date of the IPO, all series of redeemable convertible preference shares were considered to be participating securities due to their non-cumulative dividend rights. In connection with the Company’s IPO in October 2012, all outstanding redeemable convertible preference shares converted to ordinary shares. Net income has been allocated to the ordinary shares, redeemable convertible preference shares and unvested early exercised options 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,
	2014		2013		2012
Options to purchase ordinary shares		183,859		2,053,520		1,698,505
Restricted stock units		1,576		60,504		—
Employee stock purchase plan		10,597		20,356		—
Early exercised options subject to repurchase		30,661		87,627		156,890
Redeemable convertible preference shares (if-converted basis)		—		9,131,824		12,344,993
Warrants to purchase redeemable convertible preference shares (if-converted basis)		—		—		36,292
Warrants to purchase ordinary shares		—		24,889		—

		226,693		11,378,720		14,236,680

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Income Taxes

12 Months Ended

Jan. 31, 2014

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

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


	Year Ended January 31,
	2014		2013		2012
	(in thousands)
U.S. operations	$	1,990	$	3,264	$	2,923
Non-U.S. operations		25,905		16,778		8,242

Income before income taxes	$	27,895	$	20,042	$	11,165

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


	Year Ended January 31,
	2014			2013			2012
	(in thousands)
Current:
U.S. federal tax	$	1,738		$	2,022		$	962
U.S. state taxes		23			5			26
Non-U.S. foreign taxes		1,058			701			502

		2,819			2,728			1,490

Deferred:
U.S. federal tax		(952	)		(743	)		(73	)
U.S. state taxes		341			(109	)		(36	)
Non-U.S. foreign taxes		33			(22	)		(37	)

		(578	)		(874	)		(146	)

Provision for income taxes	$	2,241		$	1,854		$	1,344

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,
	2014			2013			2012
	(in thousands)
U.S. federal tax at statutory rate	$	9,484		$	6,814		$	3,796
U.S. state taxes		361			(107	)		(13	)
Non-U.S. foreign tax differential		(7,674	)		(4,513	)		(2,306	)
Stock-based compensation		927			682			537
U.S. R&D credit		(858	)		(890	)		(623	)
Other		1			(132	)		(47	)

Provision for income taxes	$	2,241		$	1,854		$	1,344

Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities at January 31, 2014 and 2013 were as follows:


	As of January 31,
	2014			2013
	(in thousands)
Deferred tax assets:
Federal and state credits	$	2,587		$	1,243
Expenses not currently deductible		1,149			1,345
Foreign deferred		26			60
Stock-based compensation		1,460			950

Gross deferred tax assets		5,222			3,598
Valuation allowance		(2,302	)		(1,243	)

Total deferred tax assets	$	2,920		$	2,355

Deferred tax liabilities
Property and equipment		(187	)		(197	)

Net deferred tax assets	$	2,733		$	2,158

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


	Balance at Beginning of Period		Additional Charged to Expenses		Additions Charged to Other Account		Deductions Charged to Expenses or Other Accounts			Balance at End of Period
	(in thousands)
Tax Valuation Allowance
Year ended January 31, 2014	$	1,243		1,059		—		—		$	2,302
Year ended January 31, 2013	$	1,301		—		—		(58	)	$	1,243
Year ended January 31, 2012	$	1,153		280		—		(132	)	$	1,301

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, 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, 2014 would be $3.2 million. Cumulative undistributed earnings of foreign subsidiaries for which no deferred taxes have been provided approximated $22.0 million at January 31, 2014.

As of January 31, 2014 and 2013, the Company had deferred tax assets (net of deferred tax liabilities) before valuation allowance, of $5.0 million and $3.4 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 Federal and California state research and development credit carryforwards of approximately $0.4 million and $3.3 million, respectively, at January 31, 2014. The federal credits begin to expire in fiscal year 2033. 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, 2014, the Company has no valuation allowance other than state deferred tax assets as the Company has sufficient positive evidence to indicate no other valuation allowance is needed as a result of the Company’s history of profitable operations in the United States. As of January 31, 2014, the Company has a full valuation allowance against its 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, 2014, the Company had approximately $3.6 million in unrecognized tax benefits, $2.4 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,
	2014			2013			2012
	(in thousands)
Beginning balance:	$	3,018		$	2,213		$	2,007
Additions based on tax positions related to the current year		539			325			311
Additions for tax positions of prior years		62			690			34
Reductions for tax positions of prior years		(36	)		(210	)		(139	)

Ending balance:	$	3,583		$	3,018		$	2,213

The Company classified $1.3 million and $1.2 million of income tax liabilities as other long term liabilities as of January 31, 2014 and 2013, 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 $37,000, $23,000 and $37,000 of interest expense and penalties related to uncertain tax positions for the years ended January 31, 2014, 2013 and 2012, respectively. The Company recorded noncurrent liabilities of $153,000 and $116,000 related to interest and penalties for uncertain tax positions at January 31, 2014 and 2013, 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, 2014, the Company’s long-term income taxes payable, including estimated interest and penalties, was approximately $1.5 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.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

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Commitments and Contingencies

12 Months Ended

Jan. 31, 2014

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

The Company leases its principal facilities and time-based software licenses under operating agreements with various expiration dates through April 2018. Net rental expenses for the years ended January 31, 2014, 2013 and 2012 were approximately $5.0 million, $4.3 million and $3.9 million, respectively. Future annual minimum lease payments under these operating leases with initial lease terms in excess of one year are as follows:


	As of January 31, 2014
Fiscal Year	(in thousands)
2015		1,928
2016		1,816
2017		1,632
2018		1,389
2019		237

Total future annual minimum lease payments	$	7,002

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, 2014 and 2013, total manufacturing purchase commitments were approximately $13.7 million and $15.1 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, 2014 and 2013, respectively.

- Definition

The entire disclosure for commitments and contingencies.

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Segment Reporting

12 Months Ended

Jan. 31, 2014

Segment Reporting [Abstract]

Segment Reporting

11. 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,
	2014		2013		2012
	(in thousands)
Hong Kong	$	135,382	$	104,458	$	80,627
Asia Pacific		2,809		550		1,350
United States		7,128		7,990		9,825
North America		4,594		2,602		1,323
Europe		7,695		5,466		4,132

Total revenue	$	157,608	$	121,066	$	97,257

As of January 31, 2014, substantially all of the Company’s long-lived tangible assets are located in the Asia Pacific region.

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 85%, 80% and 80% of total revenue for the years ended January 31, 2014, 2013 and 2012, respectively. Accounts receivable with these two customers combined accounted for approximately $15.9 million and $17.6 million as of January 31, 2014 and 2013, 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.

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+ Details

Related-Party Transactions	12 Months Ended
Related-Party Transactions	Jan. 31, 2014
Related Party Transactions [Abstract]
Related-Party Transactions	12. 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. Starting from fiscal year 2008, the Company entered into several software license agreements with Cadence Design Systems, Inc. (“Cadence”). A member of the Company’s Board of Directors is also the Chief Executive Officer, President and Director of Cadence. Under these license agreements, the Company committed to pay an aggregate amount of $10.2 million payable through January 2014. The Company paid $1.7 million, $1.8 million and $1.9 million under these agreements for the years ended January 31, 2014, 2013 and 2012, respectively. Operating lease expenses related to these agreements included in research and development cost were approximately $1.7 million, $1.8 million and $1.6 million for the years ended January 31, 2014, 2013 and 2012, respectively. In addition to the related party transactions noted above, the Company recognized revenue from sales to Wintech Microelectronics Co., Ltd, or 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, 2014. The Company recognized revenue from sales to Wintech of approximately $88.7 million, $76.5 million and $77.6 million for the years ended January 31, 2014, 2013 and 2012, respectively. As of January 31, 2014 and 2013, the Company had receivables from Wintech of approximately $7.9 million and $8.2 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.

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Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Jan. 31, 2014
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. In October 2012, in connection with its initial public offering, or IPO, the Company completed the sale of 6,000,000 ordinary shares inclusive of 1,095,349 shares sold by certain shareholders of the Company. In November 2012, a total of 900,000 ordinary shares were sold to the Company’s IPO underwriters in connection with their exercise of the over-allotment option. The public offering price of the shares sold in this offering was $6.00 per share. The total net proceeds from the offering to the Company were approximately $30.4 million after deducting underwriting discounts and commissions and other offering expenses. Upon the completion of the IPO, all 13,315,727 outstanding redeemable convertible preference shares converted into ordinary shares on a one-to-one basis and all outstanding warrants to purchase redeemable convertible preference shares converted into warrants to purchase ordinary shares.
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 collectability of accounts receivable; (ii) write down for excess and obsolete inventories; (iii) the estimated useful lives of long-lived assets; (iv) impairment of long-lived assets and financial instruments; (v) warranty obligations; (vi) the valuation of stock-based compensation and equity instruments; (vii) the probability of performance objectives achievement; (viii) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (ix) 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 all of Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationship with these two customers 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 11 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 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 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 accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature.
Cash and Cash Equivalents	*Cash and Cash Equivalents* The Company considers all highly liquid investments with maturities of less than three months at the time of purchase to be cash equivalents. Investments with maturities at the time of acquisition greater than three months but less than one year are classified as short-term investments and considered as available-for-sale in current operations. There were no cash equivalents and short-term investments as of January 31, 2014 and 2013, respectively.
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 write-offs of accounts receivable for fiscal years 2014, 2013 and 2012, respectively. There was no allowance for doubtful accounts recorded as of January 31, 2014 and 2013, 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 has been established and, accordingly, any associated reserve is not reversed until the inventory sold or scrapped. There has been no material inventory loss to date to be recognized.
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, 2014, the Company has capitalized approximately $1.1 million of internal-use software and has been recorded in property and equipment, net on the consolidated balance sheets.
Impairment of Long-Lived Assets	*Impairment of Long-Lived Assets* The Company records long-lived assets at cost and evaluates them for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. 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. When the sum of the expected future undiscounted cash flows expected to be generated by the related asset group is less than its carrying amount, an impairment loss would be recognized. Should impairment exist, the impairment loss would be measured based on the excess of the carrying amount of the asset over the asset’s estimated fair value. 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, 2014.
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, the Company has not recognized any impairment losses related to this investment.
Revenue Recognition	*Revenue Recognition* The Company generates revenue from the sale 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 right 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 sells a limited amount of software under perpetual licenses that include post-contract customer support, or PCS. The Company does not have evidence of fair value for the PCS and, accordingly, license revenue is recognized ratably over the estimated supporting period in accordance with ASC 985, Software Revenue Recognition. The Company also enters into development agreements with certain customers. Revenue is deferred for any amounts billed prior to delivery of development services. However, if the Company retains the intellectual property generated from these development agreements, receipts and costs related to these arrangements are included in research and development expense. The revenue from those licenses and services were not material for the years ended January 31, 2014, 2013 and 2012, 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 have not been material to date.
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 have not been material to date.
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 estimates the fair value of restricted stock units, or RSUs, 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. Prior to the initial public offering, or IPO, the Company engaged an independent appraiser to assist in the valuation of its ordinary share price. The board of directors directed these regular valuations and had input into determining the relevant objective and subjective factors accounted for and relevant approaches in each valuation. After the IPO, the exercise price of stock option awards is determined by the closing price of the Company’s ordinary shares traded on The NASDAQ Global Market on the grant 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 Employee Stock Purchase Plan, or ESPP, upon release of vested restricted stock units, upon conversion of its redeemable convertible preference shares and upon exercise of warrants. 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	*Comprehensive Income* There are no differences between comprehensive income as defined by ASC 220, Comprehensive Income, and net income as reported in the Company’s consolidated statements of operations.
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In February 2013, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“AOCI”). This new guidance requires that the Company present either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, the Company would instead cross reference to the related footnote for additional information. This guidance only impacts disclosures within the Company’s consolidated financial statements and notes to the consolidated financial statements and does not result in a change to the accounting treatment of AOCI. This new guidance became effective prospectively for fiscal years, and interim periods with those years, beginning after December 15, 2012. The Company adopted this guidance starting from the first quarter of fiscal year 2014 and the adoption did not have an impact on its financial position, results of operations or disclosures. In July 2013, the FASB issued ASU No. 2013-11, Income Taxes (Topic 740), Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss ,or a Tax Credit Carryforward Exists. The new guidance requires the netting of unrecognized tax benefits (“UTBs”) against a deferred tax asset for a loss or other carryforward that would apply in settlement of the uncertain tax positions. Under the new standard, UTBs will be netted against all available same-jurisdiction loss or other tax carryforwards that would be utilized, rather than only against carryforwards that are created by the UTBs. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013 and should be applied prospectively to all unrecognized tax benefits that exist at the effective date. Early adoption and retrospective application are permitted. The Company has not yet adopted this guidance but does not expect the adoption of this guidance to have a significant impact on its financial position, results of operations, statement of cash flows or disclosures.

Inventories (Tables)

12 Months Ended

Jan. 31, 2014

Inventory Disclosure [Abstract]

Schedule of Inventories

Inventories at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014		2013
	(in thousands)
Work-in-progress	$	5,119	$	3,012
Finished goods		5,333		5,906

Total	$	10,452	$	8,918

Property and Equipment, Net (Tables)

12 Months Ended

Jan. 31, 2014

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014			2013
	(in thousands)
Computer equipment and software	$	4,521		$	2,810
Machinery and equipment		2,114			2,050
Furniture and fixtures		411			397
Leasehold improvements		1,198			642
Construction in progress		—			827

		8,244			6,726

Less: accumulated depreciation and amortization		(5,226	)		(4,190	)

Total property and equipment, net	$	3,018		$	2,536

Accrued Liabilities (Tables)

12 Months Ended

Jan. 31, 2014

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014		2013
	(in thousands)
Accrued employee compensation	$	8,049	$	8,599
Refundable exercised unvested options		59		210
Accrued warranty		269		352
Accrued rebates		270		272
Accrued product development costs		1,904		2,875
Other accrued liabilities		1,154		1,734

Total accrued liabilities	$	11,705	$	14,042

Deferred Revenue, net (Tables)

12 Months Ended

Jan. 31, 2014

Revenue Recognition [Abstract]

Schedule of Deferred Revenue and Related Cost

Deferred revenue and related cost at January 31, 2014 and 2013 consisted of the following:


	As of January 31,
	2014			2013
	(in thousands)
Deferred revenue on product shipments	$	5,174		$	3,827
Deferred revenue from licenses & services		1,023			485
Deferred cost of revenue on product shipments		(1,366	)		(861	)

Total deferred revenue, net	$	4,831		$	3,451

Capital Stock (Tables)

12 Months Ended

Jan. 31, 2014

Text Block [Abstract]

Components of Redeemable Convertible Preference Shares

Redeemable convertible preference shares at January 31, 2012 consisted of the following:


	Par Value Per Share		Shares				Initial Liquidation Preference
Series	Par Value Per Share		Authorized		Outstanding		Initial Liquidation Preference
							(in thousands)
A	$	0.00045		5,611,111		5,611,107	$	10,100
B	$	0.00045		3,665,550		3,629,253		13,000
C	$	0.00045		3,027,777		3,027,771		16,350
D	$	0.00045		2,222,222		1,047,596		11,785

				14,526,660		13,315,727	$	51,235

Schedule of Ordinary Shares Reserved for Future Issuance

As of January 31, 2014 and 2013, the following ordinary shares were reserved for future issuance:


	As of January 31,
	2014		2013
Shares reserved for options and restricted stock units		5,699,530		5,818,126
Shares reserved for employee stock purchase plan		456,410		460,445
Shares reserved for warrants		—		36,292

- Definition

Tabular disclosure of temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References+ Details

Employee Benefits and Stock-based Compensation (Tables)

12 Months Ended

Jan. 31, 2014

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,
	2014		2013		2012
	(in thousands)
Stock-based compensation:
Cost of revenue	$	178	$	92	$	52
Research and development		4,887		2,942		1,821
Selling, general and administrative		3,470		1,965		1,743

Total stock-based compensation	$	8,535	$	4,999	$	3,616

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,
	2014			2013			2012
Stock Options:
Volatility		65	%		66	%		65	%
Risk-free interest rate		1.55	%		0.91	%		1.64	%
Expected term (years)		6.06			6.05			6.05
Dividend yield		0	%		0	%		0	%

Employee stock purchase plan awards:
Volatility		52	%		51	%		N/A
Risk-free interest rate		0.04	%		0.18	%		N/A
Expected term (years)		0.5			0.94			N/A
Dividend yield		0	%		0	%		N/A

Stock Option Activities

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


	Option Outstanding
	Shares			Weighted- Average Exercise Price		Weighted- Average Grant-date Fair Value		Total Intrinsic Value of options Exercised (in thousands)		Weighted- Average Remaining Contactual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 31, 2011		3,814,782			4.35
Granted		1,207,564			8.82	$	5.24
Exercised		(454,053	)		2.91			$	2,682
Forfeited		(192,387	)		6.78

Outstanding at January 31, 2012		4,375,906			5.63
Granted		451,071			8.79	$	5.23
Exercised		(313,827	)		3.21			$	2,087
Forfeited		(168,615	)		7.22

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						6.24	$	84,334
Exercisable at January 31, 2014		2,529,324			5.57						5.62	$	66,919
Vested and expected to vest at January 31, 2014		3,318,394			6.86						6.22	$	83,532

Restricted Stock Units Activities

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


	Shares			Weighted- Average Grant-Date Fair Value
Unvested at January 31, 2012		—		$	—
Granted		345,171			9.99
Vested		—			—
Forfeited		(5,954	)		9.99

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

Net Income Per Ordinary Share (Tables)

12 Months Ended

Jan. 31, 2014

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,
	2014			2013			2012
	(in thousands, except share and per share data)
Numerator:
Net income	$	25,654		$	18,188		$	9,821
Less: amount allocable to preference shareholders		—			(9,517	)		(7,204	)
Less: amount allocable to unvested early exercised options		(31	)		(61	)		(51	)

Net income allocable to ordinary shareholders—basic	$	25,623		$	8,610		$	2,566

Undistributed earnings reallocated to ordinary shareholders		2			432			277

Net income allocable to ordinary shareholders—diluted	$	25,625		$	9,042		$	2,843

Denominator:
Weighted-average ordinary shares outstanding		27,713,998			13,599,273			8,118,834
Less: weighted-average unvested early exercised options subject to repurchase		(33,220	)		(87,627	)		(156,890	)

Weighted-average ordinary shares—basic		27,680,778			13,511,646			7,961,944

Effect of potentially dilutive securities:
Employee stock options		2,034,500			1,443,809			1,507,876
Restricted stock units		316,350			16,930			—
Employee stock purchase plan		138,461			27,230			—
Warrants to purchase ordinary shares		2,474			6,737			—
Over-allotment shares		—			10,634			—
Weighted-average ordinary shares—diluted		30,172,563			15,016,986			9,469,820

Net income per ordinary share:
Basic	$	0.93		$	0.64		$	0.32

Diluted	$	0.85		$	0.60		$	0.30

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,
	2014		2013		2012
Options to purchase ordinary shares		183,859		2,053,520		1,698,505
Restricted stock units		1,576		60,504		—
Employee stock purchase plan		10,597		20,356		—
Early exercised options subject to repurchase		30,661		87,627		156,890
Redeemable convertible preference shares (if-converted basis)		—		9,131,824		12,344,993
Warrants to purchase redeemable convertible preference shares (if-converted basis)		—		—		36,292
Warrants to purchase ordinary shares		—		24,889		—

		226,693		11,378,720		14,236,680

Income Taxes (Tables)

12 Months Ended

Jan. 31, 2014

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,
	2014		2013		2012
	(in thousands)
U.S. operations	$	1,990	$	3,264	$	2,923
Non-U.S. operations		25,905		16,778		8,242

Income before income taxes	$	27,895	$	20,042	$	11,165

Schedule of Income Tax Provision

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


	Year Ended January 31,
	2014			2013			2012
	(in thousands)
Current:
U.S. federal tax	$	1,738		$	2,022		$	962
U.S. state taxes		23			5			26
Non-U.S. foreign taxes		1,058			701			502

		2,819			2,728			1,490

Deferred:
U.S. federal tax		(952	)		(743	)		(73	)
U.S. state taxes		341			(109	)		(36	)
Non-U.S. foreign taxes		33			(22	)		(37	)

		(578	)		(874	)		(146	)

Provision for income taxes	$	2,241		$	1,854		$	1,344

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,
	2014			2013			2012
	(in thousands)
U.S. federal tax at statutory rate	$	9,484		$	6,814		$	3,796
U.S. state taxes		361			(107	)		(13	)
Non-U.S. foreign tax differential		(7,674	)		(4,513	)		(2,306	)
Stock-based compensation		927			682			537
U.S. R&D credit		(858	)		(890	)		(623	)
Other		1			(132	)		(47	)

Provision for income taxes	$	2,241		$	1,854		$	1,344

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, 2014 and 2013 were as follows:


	As of January 31,
	2014			2013
	(in thousands)
Deferred tax assets:
Federal and state credits	$	2,587		$	1,243
Expenses not currently deductible		1,149			1,345
Foreign deferred		26			60
Stock-based compensation		1,460			950

Gross deferred tax assets		5,222			3,598
Valuation allowance		(2,302	)		(1,243	)

Total deferred tax assets	$	2,920		$	2,355

Deferred tax liabilities
Property and equipment		(187	)		(197	)

Net deferred tax assets	$	2,733		$	2,158

Summary of Tax Valuation Allowance

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


	Balance at Beginning of Period		Additional Charged to Expenses		Additions Charged to Other Account		Deductions Charged to Expenses or Other Accounts			Balance at End of Period
	(in thousands)
Tax Valuation Allowance
Year ended January 31, 2014	$	1,243		1,059		—		—		$	2,302
Year ended January 31, 2013	$	1,301		—		—		(58	)	$	1,243
Year ended January 31, 2012	$	1,153		280		—		(132	)	$	1,301

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,
	2014			2013			2012
	(in thousands)
Beginning balance:	$	3,018		$	2,213		$	2,007
Additions based on tax positions related to the current year		539			325			311
Additions for tax positions of prior years		62			690			34
Reductions for tax positions of prior years		(36	)		(210	)		(139	)

Ending balance:	$	3,583		$	3,018		$	2,213

Commitments and Contingencies (Tables)

12 Months Ended

Jan. 31, 2014

Commitments And Contingencies Disclosure [Abstract]

Future Annual Minimum Lease Payments

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


	As of January 31, 2014
Fiscal Year	(in thousands)
2015		1,928
2016		1,816
2017		1,632
2018		1,389
2019		237

Total future annual minimum lease payments	$	7,002

Segment Reporting (Tables)

12 Months Ended

Jan. 31, 2014

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,
	2014		2013		2012
	(in thousands)
Hong Kong	$	135,382	$	104,458	$	80,627
Asia Pacific		2,809		550		1,350
United States		7,128		7,990		9,825
North America		4,594		2,602		1,323
Europe		7,695		5,466		4,132

Total revenue	$	157,608	$	121,066	$	97,257

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Nov. 30, 2012	Oct. 31, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Initial public offering of shares		6,000,000
Shares issued during period, shares sold by certain shareholders		1,095,349
Over-allotment option shares sold	900,000
Initial public offering price per share	$ 6.00	$ 6.00
Net proceeds from shares issued upon initial public offering and over-allotment share options exercised	$ 30.4
Redeemable convertible preference shares converted to ordinary shares		13,315,727
Redeemable convertible preference shares conversion		Converted into ordinary shares on a one-to-one basis
Cash equivalents, treatment			Highly liquid investments with maturities of less than three months at the time of purchase to be cash equivalents.
Short-term investment, treatment			Investments with maturities at the time of acquisition greater than three months but less than one year are classified as short-term investments
Cash equivalents and short-term investments			0	0
Write-offs of accounts receivable			0	0	0
Allowance for doubtful accounts			0	0
Estimated useful life			3 years	3 years	3 years
Capitalizes internal-use software			1.1
Impairment of long-lived assets			0
Impairment losses on investment			$ 0
Expected dividend yield			0.00%	0.00%	0.00%

Inventories - Schedule of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Inventory Disclosure [Abstract]
Work-in-progress	$ 5,119	$ 3,012
Finished goods	5,333	5,906
Total	$ 10,452	$ 8,918

- Definition

Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

+ References+ Details

Property and Equipment, Net - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Mar. 31, 2013 sqft	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation		$ 1,096,000	$ 737,000	$ 596,000
Lease agreement new headquarters	35,000
Initial lease term	5 years
Capitalized internal-use software		1,100,000
Leasehold improvement [Member]
Property, Plant and Equipment [Line Items]
Capitalized leasehold improvement		700,000
Internal-use software [Member]
Property, Plant and Equipment [Line Items]
Capitalized internal-use software		$ 1,100,000
Estimated economic useful life		3 years

Property and Equipment, Net - Schedule of Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Property Plant And Equipment [Abstract]
Computer equipment and software	$ 4,521	$ 2,810
Machinery and equipment	2,114	2,050
Furniture and fixtures	411	397
Leasehold improvements	1,198	642
Construction in progress		827
Property and equipment, gross	8,244	6,726
Less: accumulated depreciation and amortization	(5,226)	(4,190)
Total property and equipment, net	$ 3,018	$ 2,536

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Payables And Accruals [Abstract]
Accrued employee compensation	$ 8,049	$ 8,599
Refundable exercised unvested options	59	210
Accrued warranty	269	352
Accrued rebates	270	272
Accrued product development costs	1,904	2,875
Other accrued liabilities	1,154	1,734
Total accrued liabilities	$ 11,705	$ 14,042

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers. For classified balance sheets, represents the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

Deferred Revenue, net - Schedule of Deferred Revenue and Related Cost (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Deferred Revenue Arrangement [Line Items]
Deferred cost of revenue on product shipments	$ (1,366)	$ (861)
Deferred revenue	4,831	3,451
Product shipments [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue	5,174	3,827
Licenses & services [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 1,023	$ 485

Capital Stock - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended
Capital Stock - Additional Information (Detail) (USD $)	Nov. 30, 2012	Oct. 31, 2012	Jan. 31, 2012	Jan. 31, 2012	Jan. 31, 2014	Jan. 31, 2013
Class of Stock [Line Items]
Net proceeds from issuance of preference shares				$ 11,627,000
Redeemable convertible preference shares conversion		Converted into ordinary shares on a one-to-one basis
Repurchase of ordinary shares price per share			$ 10.35	$ 10.35
Number of ordinary shares repurchased			698,424	698,424
Cash paid for repurchase of ordinary shares			7,228,000	7,228,000
Initial public offering of shares		6,000,000
Shares sold by selling shareholders upon initial public offering		1,095,349
Over-allotment option shares sold	900,000
Initial public offering price per share	$ 6.00	$ 6.00
Net proceeds from shares issued upon initial public offering and over-allotment share options exercised	30,400,000
Redeemable convertible preference shares converted to ordinary shares		13,315,727
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
Company issued warrants to purchase redeemable convertible preference shares, exercise price			3.582	3.582
Company issued warrants to purchase redeemable convertible preference shares			36,292	36,292
Aggregate fair market value		110,000
Total ordinary share warrants outstanding					0
Ordinary shares authorized					200,000,000	200,000,000
Series D Redeemable convertible preference shares [Member]
Class of Stock [Line Items]
Issuance of preference shares			1,047,596	1,047,596
Preference shares, price per share			$ 11.25	$ 11.25
Net proceeds from issuance of preference shares			$ 11,627,000	$ 11,627,000
Redeemable convertible preference shares conversion		Converted into ordinary shares on a one-to-one basis.

Capital Stock - Components of Redeemable Convertible Preference Shares (Detail) (Redeemable Convertible Preference Shares [Member], USD $) In Thousands, except Share data, unless otherwise specified	Jan. 31, 2012
Class of Stock [Line Items]
Preference shares, Shares Authorized	14,526,660
Preference shares, Shares Outstanding	13,315,727
Initial Liquidation Preference	$ 51,235
Series A Redeemable convertible preference shares [Member]
Class of Stock [Line Items]
Preference shares, par value	$ 0.00045
Preference shares, Shares Authorized	5,611,111
Preference shares, Shares Outstanding	5,611,107
Initial Liquidation Preference	10,100
Series B Redeemable convertible preference shares [Member]
Class of Stock [Line Items]
Preference shares, par value	$ 0.00045
Preference shares, Shares Authorized	3,665,550
Preference shares, Shares Outstanding	3,629,253
Initial Liquidation Preference	13,000
Series C Redeemable convertible preference shares [Member]
Class of Stock [Line Items]
Preference shares, par value	$ 0.00045
Preference shares, Shares Authorized	3,027,777
Preference shares, Shares Outstanding	3,027,771
Initial Liquidation Preference	16,350
Series D Redeemable convertible preference shares [Member]
Class of Stock [Line Items]
Preference shares, par value	$ 0.00045
Preference shares, Shares Authorized	2,222,222
Preference shares, Shares Outstanding	1,047,596
Initial Liquidation Preference	$ 11,785

- Definition

The maximum number of securities classified as temporary equity that are permitted to be issued by an entity's charter and bylaws. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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- Definition

The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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Employee Benefits and Stock-based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Voting power of all classes of company's shares	10.00%	10.00%	10.00%
Term of up to 10 years from grant date	10 years	10 years	10 years
Vesting period of stock options	Vest 25% on the first anniversary date of the grant and remainder vest ratably over the following 36 months.	Vest 25% on the first anniversary date of the grant and remainder vest ratably over the following 36 months.	Vest 25% on the first anniversary date of the grant and remainder vest ratably over the following 36 months.
Percentage of salary contribution by employees	10.00%	10.00%
Percentage of purchase price of ordinary shares	85.00%	85.00%
Unvested early exercised options repurchased	86,340	84,377
Unvested shares subject to the Company's repurchase rights	13,289	53,151
Closing price of ordinary shares	$ 32.03
Non-employee stock-based compensation
Unvested stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost, stock options	5.8	7.3
Weighted-average period	1 year 10 months 24 days	2 years 3 months 4 days
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost, restricted stock units	17.0	2.4
Weighted-average period	2 years 11 months 27 days	1 year 9 months 7 days
Aggregate intrinsic value of unvested restricted stock units	$ 45.2
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of RSUs	1/4th of the shares on the first anniversary date of the grant and 1/16th of the RSUs vest every 3 months thereafter, so as to be 100% vested on the fourth anniversary of the vesting commencement date.	1/4th of the shares on the first anniversary date of the grant and 1/16th of the RSUs vest every 3 months thereafter, so as to be 100% vested on the fourth anniversary of the vesting commencement date.
Incentive stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value at grant date	110.00%
Non statutory stock option plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value at grant date	100.00%
2012 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increases in the number of shares available for issuance	1,500,000	1,500,000
Annual increases in percentage in the number of shares available for issuance	1.25%	1.25%
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increases in the number of shares available for issuance	3,500,000	3,500,000
Annual increases in percentage in the number of shares available for issuance	4.50%	4.50%

Employee Benefits and Stock-based Compensation - Classification of Stock-based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Stock-based compensation:
Total stock-based compensation	$ 8,535	$ 4,999	$ 3,616
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	178	92	52
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	4,887	2,942	1,821
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 3,470	$ 1,965	$ 1,743

Employee Benefits and Stock-based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value (Detail)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Options to purchase ordinary shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	65.00%	66.00%	65.00%
Risk-free interest rate	1.55%	0.91%	1.64%
Expected term (years)	6 years 22 days	6 years 18 days	6 years 18 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	52.00%	51.00%
Risk-free interest rate	0.04%	0.18%
Expected term (years)	6 months	11 months 9 days
Dividend yield	0.00%	0.00%

Employee Benefits and Stock-based Compensation - Stock Option Activities (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding	4,344,535	4,375,906	3,814,782
Shares, Granted	255,520	451,071	1,207,564
Shares, Exercised	(1,160,286)	(313,827)	(454,053)
Shares, Forfeited	(81,063)	(168,615)	(192,387)
Shares, Outstanding	3,358,706	4,344,535	4,375,906
Shares, Exercisable	2,529,324
Shares, Vested and expected to vest	3,318,394
Weighted-Average Exercise Price, Outstanding	$ 6.07	$ 5.63	$ 4.35
Weighted-Average Exercise Price, Granted	$ 18.14	$ 8.79	$ 8.82
Weighted-Average Exercise Price, Exercised	$ 5.96	$ 3.21	$ 2.91
Weighted-Average Exercise Price, Forfeited	$ 10.34	$ 7.22	$ 6.78
Weighted-Average Exercise Price, Outstanding	$ 6.92	$ 6.07	$ 5.63
Weighted-Average Exercise Price, Exercisable	$ 5.57
Weighted-Average Exercise Price, Vested and expected to vest	$ 6.86
Weighted-Average Grant-date Fair Value, Granted	$ 10.85	$ 5.23	$ 5.24
Total Intrinsic Value of options Exercised, Exercised	$ 18,217	$ 2,087	$ 2,682
Weighted-Average Remaining Contractual Term, Outstanding	6 years 2 months 27 days
Weighted-Average Remaining Contractual Term, Exercisable	5 years 7 months 13 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	6 years 2 months 19 days
Aggregate Intrinsic Value, Outstanding	84,334
Aggregate Intrinsic Value, Exercisable	66,919
Aggregate Intrinsic Value, Vested and expected to vest	$ 83,532

Employee Benefits and Stock-based Compensation - Restricted Stock Units Activities (Detail) (Restricted stock units [Member], USD $)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Unvested, beginning balance	339,217
Shares, Granted	1,265,472	345,171
Shares, Vested	(174,888)
Shares, Forfeited	(19,712)	(5,954)
Shares, Unvested, ending balance	1,410,089	339,217
Weighted-Average Grant-Date Fair Value, Unvested beginning balance	$ 9.99
Weighted-Average Grant-Date Fair Value, Granted	$ 14.78	$ 9.99
Weighted-Average Grant-Date Fair Value, Vested	$ 11.91
Weighted-Average Grant-Date Fair Value, Forfeited	$ 11.97	$ 9.99
Weighted-Average Grant-Date Fair Value, Unvested ending balance	$ 14.02	$ 9.99

Net Income Per Ordinary Share - Computation of Basic and Diluted Net Income Per Ordinary Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Numerator:
Net income	$ 25,654	$ 18,188	$ 9,821
Less: amount allocable to preference shareholders		(9,517)	(7,204)
Less: amount allocable to unvested early exercised options	(31)	(61)	(51)
Net income allocable to ordinary shareholders-basic	25,623	8,610	2,566
Undistributed earnings reallocated to ordinary shareholders	2	432	277
Net income allocable to ordinary shareholders-diluted	$ 25,625	$ 9,042	$ 2,843
Denominator:
Weighted-average ordinary shares outstanding	27,713,998	13,599,273	8,118,834
Less: weighted-average unvested early exercised options subject to repurchase	(33,220)	(87,627)	(156,890)
Weighted-average ordinary shares-basic	27,680,778	13,511,646	7,961,944
Effect of potentially dilutive securities:
Employee stock options	2,034,500	1,443,809	1,507,876
Restricted stock units	316,350	16,930
Employee stock purchase plan	138,461	27,230
Warrants to purchase ordinary shares	2,474	6,737
Over-allotment shares		10,634
Weighted-average ordinary shares-diluted	30,172,563	15,016,986	9,469,820
Net income per ordinary share:
Basic	$ 0.93	$ 0.64	$ 0.32
Diluted	$ 0.85	$ 0.60	$ 0.30

Net Income Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Net Income Per Ordinary Share (Detail)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	226,693	11,378,720	14,236,680
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	183,859	2,053,520	1,698,505
Restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	1,576	60,504
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	10,597	20,356
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	30,661	87,627	156,890
Redeemable Convertible Preference Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share		9,131,824	12,344,993
Warrants to purchase redeemable convertible preference shares (if-converted basis) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share			36,292
Warrants 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		24,889

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References+ Details

Income Taxes - Summary of Income before Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Results Of Operations Income Before Income Taxes [Abstract]
U.S. operations	$ 1,990	$ 3,264	$ 2,923
Non-U.S. operations	25,905	16,778	8,242
Income before income taxes	$ 27,895	$ 20,042	$ 11,165

Income Taxes - Schedule of Income Tax Provision (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Current:
U.S. federal tax	$ 1,738	$ 2,022	$ 962
U.S. state taxes	23	5	26
Non-U.S. foreign taxes	1,058	701	502
Current income tax provision	2,819	2,728	1,490
Deferred:
U.S. federal tax	(952)	(743)	(73)
U.S. state taxes	341	(109)	(36)
Non-U.S. foreign taxes	33	(22)	(37)
Deferred income tax provision	(578)	(874)	(146)
Provision for income taxes	$ 2,241	$ 1,854	$ 1,344

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Income Taxes [Line Items]
U.S. federal income tax rate	34.00%	34.00%	34.00%
Deferred tax liabilities, not recognized	$ 3,200,000
Cumulative undistributed earnings of foreign subsidiaries	22,000,000
Gross deferred tax assets, net of deferred tax liabilities before valuation allowance	5,035,000	3,401,000
Unrecognized tax benefits	3,583,000	3,018,000	2,213,000	2,007,000
Unrecognized tax benefits that would impact effective tax rate	2,400,000
Income tax liabilities considered as other long term liabilities	1,300,000	1,200,000
Interest expense and penalties related to uncertain tax positions	37,000	23,000	37,000
Noncurrent liabilities related to interest and penalties for uncertain tax positions	153,000	116,000
Long term income taxes payable, including estimated interest and penalties	1,500,000
Federal [Member]
Income Taxes [Line Items]
Research and development credit carryforwards	400,000
Credits begin to expire in fiscal year	2033
California state [Member]
Income Taxes [Line Items]
Research and development credit carryforwards	$ 3,300,000

Income Taxes - Schedule of Income Tax Provision Differed from Amounts Computed by Applying U.S. Federal Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Tax Disclosure [Abstract]
U.S. federal tax at statutory rate	$ 9,484	$ 6,814	$ 3,796
U.S. state taxes	361	(107)	(13)
Non-U.S. foreign tax differential	(7,674)	(4,513)	(2,306)
Stock-based compensation	927	682	537
U.S. R&D credit	(858)	(890)	(623)
Other	1	(132)	(47)
Provision for income taxes	$ 2,241	$ 1,854	$ 1,344

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Deferred tax assets:
Federal and state credits	$ 2,587	$ 1,243
Expenses not currently deductible	1,149	1,345
Foreign deferred	26	60
Stock-based compensation	1,460	950
Gross deferred tax assets	5,222	3,598
Valuation allowance	(2,302)	(1,243)
Total deferred tax assets	2,920	2,355
Deferred tax liabilities
Property and equipment	(187)	(197)
Net deferred tax assets	$ 2,733	$ 2,158

Income Taxes - Summary of Tax Valuation Allowance (Detail) (Valuation Allowance of Deferred Tax Assets [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1,243	$ 1,301	$ 1,153
Additional Charged to Expenses	1,059		280
Additions Charged to Other Account
Deductions Charged to Expenses or Other Accounts		(58)	(132)
Balance at End of Period	$ 2,302	$ 1,243	$ 1,301

Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Tax Disclosure [Abstract]
Beginning balance	$ 3,018	$ 2,213	$ 2,007
Additions based on tax positions related to the current year	539	325	311
Additions for tax positions of prior years	62	690	34
Reductions for tax positions of prior years	(36)	(210)	(139)
Ending balance	$ 3,583	$ 3,018	$ 2,213

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Loss Contingencies [Line Items]
Net rental expenses	$ 5,000,000	$ 4,300,000	$ 3,900,000
Total manufacturing purchase commitments	13,700,000	15,100,000
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) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
2015	$ 1,928
2016	1,816
2017	1,632
2018	1,389
2019	237
Total future annual minimum lease payments	$ 7,002

Segment Reporting - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Concentration Risk [Line Items]
Number of reportable segment	1
Accounts receivable	$ 18,837	$ 20,153
Wintech And Chicony [Member]
Concentration Risk [Line Items]
Accounts receivable	$ 15,900	$ 17,600
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%
Wintech And Chicony [Member] \| Sales revenue, net [Member] \| Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	85.00%	80.00%	80.00%
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%

Segment Reporting - Company's Revenue by Geographic Region (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Revenue from External Customer [Line Items]
Total revenue	$ 157,608	$ 121,066	$ 97,257
Hong Kong [Member]
Revenue from External Customer [Line Items]
Total revenue	135,382	104,458	80,627
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	2,809	550	1,350
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	7,128	7,990	9,825
North America [Member]
Revenue from External Customer [Line Items]
Total revenue	4,594	2,602	1,323
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 7,695	$ 5,466	$ 4,132

Related-Party Transactions - Additional Information (Detail) (Related party [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Related party [Member]
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%	10.00%	10.00%
Total commitment payment of license	$ 10.2	$ 10.2	$ 10.2
Payment for license fees	1.7	1.8	1.9
Operating lease expense related to license agreements included in research and development cost	1.7	1.8	1.6
Percentage of investor own voting stock		4.60%
Recognized revenue from related party	88.7	76.5	77.6
Account receivables from related party	$ 7.9	$ 8.2

- Definition

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

+ References+ Details

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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Subsequent Event - Additional Information (Detail) (Subsequent Events [Member], USD $) In Millions, unless otherwise specified	Mar. 28, 2014	Feb. 28, 2014
Subsequent Events [Member]
Subsequent Event [Line Items]
Liquid debt securities		$ 30.0
Fair value of marketable debt securities	$ 30.0

Subsequent Event	12 Months Ended
Subsequent Event	Jan. 31, 2014
Subsequent Events [Abstract]
Subsequent Event	13. Subsequent Event In February 2014, the Company invested $30.0 million in high quality, highly liquid debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies. The Company holds all of these marketable securities as available-for-sale and marks them to market. As of March 28, 2014, the marketable securities had a fair value of approximately $30.0 million with insignificant unrealized gain and loss. The Company cannot provide any assurance of the investment portfolio and any significant impairment charge for credit losses could adversely impact its financial position and results.

Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance (Detail)	Jan. 31, 2014	Jan. 31, 2013
Options and restricted stock units [Member]
Class of Stock [Line Items]
Shares reserved	5,699,530	5,818,126
Employee stock purchase plan [Member]
Class of Stock [Line Items]
Shares reserved	456,410	460,445
Warrants [Member]
Class of Stock [Line Items]
Shares reserved		36,292