Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Oct. 31, 2019	Dec. 02, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Oct. 31, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	AMBA
Entity Registrant Name	AMBARELLA INC
Entity Central Index Key	0001280263
Current Fiscal Year End Date	--01-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		33,544,802
Entity File Number	001-35667
Entity Tax Identification Number	98-0459628
Entity Address, Address Line One	3101 Jay Street
Entity Address, City or Town	Santa Clara
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95054
City Area Code	408
Local Phone Number	734-8888
Entity Incorporation, State or Country Code	E9
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Ordinary Shares, $0.00045 Par Value Per Share
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Current assets:
Cash and cash equivalents	$ 252,310	$ 194,047
Marketable debt securities	148,481	164,861
Accounts receivable, net	21,609	26,212
Inventories	19,845	18,252
Restricted cash	9	11
Prepaid expenses and other current assets	5,174	6,206
Total current assets	447,428	409,589
Property and equipment, net	5,927	6,728
Deferred tax assets, non-current	10,320	10,587
Intangible assets, net	8,232	10,936
Operating lease right-of-use assets, net	10,595	0
Goodwill	26,601	26,601
Other non-current assets	5,386	2,412
Total assets	514,489	466,853
Current liabilities:
Accounts payable	18,697	12,801
Accrued and other current liabilities	28,447	24,700
Operating lease liabilities, current	2,161	0
Income taxes payable	955	993
Deferred revenue, current	545	529
Total current liabilities	50,805	39,023
Operating lease liabilities, non-current	8,519	0
Other long-term liabilities	9,925	8,341
Total liabilities	69,249	47,364
Commitments and contingencies (Note 13)	0	0
Shareholders' equity:
Preference shares, $0.00045 par value per share, 20,000,000 shares authorized and no shares issued and outstanding at October 31, 2019 and January 31, 2019, respectively	0	0
Ordinary shares, $0.00045 par value per share, 200,000,000 shares authorized at October 31, 2019 and January 31, 2019, respectively; 33,540,324 shares issued and outstanding at October 31, 2019; 32,303,540 shares issued and outstanding at January 31, 2019	15	15
Additional paid-in capital	245,490	188,516
Accumulated other comprehensive income	685	97
Retained earnings	199,050	230,861
Total shareholders’ equity	445,240	419,489
Total liabilities and shareholders' equity	$ 514,489	$ 466,853

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Oct. 31, 2019	Jan. 31, 2019
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	33,540,324	32,303,540
Ordinary shares, shares outstanding	33,540,324	32,303,540

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Income Statement [Abstract]
Revenue	$ 67,922	$ 57,286	$ 171,520	$ 176,698
Cost of revenue	28,819	22,701	72,127	69,208
Gross profit	39,103	34,585	99,393	107,490
Operating expenses:
Research and development	32,480	31,653	95,917	95,446
Selling, general and administrative	13,791	12,354	39,293	38,098
Total operating expenses	46,271	44,007	135,210	133,544
Loss from operations	(7,168)	(9,422)	(35,817)	(26,054)
Other income, net	1,917	993	6,308	2,517
Loss before income taxes	(5,251)	(8,429)	(29,509)	(23,537)
Provision (benefit) for income taxes	(942)	592	2,302	2,367
Net loss	$ (4,309)	$ (9,021)	$ (31,811)	$ (25,904)
Net loss per share attributable to ordinary shareholders:
Basic	$ (0.13)	$ (0.28)	$ (0.97)	$ (0.79)
Diluted	$ (0.13)	$ (0.28)	$ (0.97)	$ (0.79)
Weighted-average shares used to compute net loss per share attributable to ordinary shareholders:
Basic	33,304,171	32,171,890	32,885,729	32,908,614
Diluted	33,304,171	32,171,890	32,885,729	32,908,614

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (4,309)	$ (9,021)	$ (31,811)	$ (25,904)
Other comprehensive income, net of tax:
Net unrealized gains on investments	140	26	588	94
Other comprehensive income, net of tax	140	26	588	94
Comprehensive loss	$ (4,169)	$ (8,995)	$ (31,223)	$ (25,810)

- Definition

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

+ References + Details

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Outstanding Ordinary Shares [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Beginning Balance, Amount at Jan. 31, 2018	$ 482,187	$ 15	$ 221,186	$ (279)	$ 261,265
Beginning Balance, Shares at Jan. 31, 2018		33,489,614
Cumulative effect of change in accounting principle	43	$ 0	0	0	43
Issuance of shares through employee equity incentive plan, Amount	305	$ 0	305	0	0
Issuance of shares through employee equity incentive plan, Shares		272,723
Issuance of shares through employee stock purchase plan, Amount	2,818	$ 0	2,818	0	0
Issuance of shares through employee stock purchase plan, Shares		71,415
Stock repurchase, Amount	(20,624)	$ 0	(20,624)	0	0
Stock repurchase, Shares		(437,448)
Stock-based compensation expense related to stock awards granted to employees and consultants	14,195	$ 0	14,195	0	0
Net unrealized gains (losses) on investments - net of taxes	(110)	0	0	(110)	0
Net loss	(10,006)	0	0	0	(10,006)
Ending Balance, Amount at Apr. 30, 2018	468,808	$ 15	217,880	(389)	251,302
Ending Balance, Shares at Apr. 30, 2018		33,396,304
Beginning Balance, Amount at Jan. 31, 2018	482,187	$ 15	221,186	(279)	261,265
Beginning Balance, Shares at Jan. 31, 2018		33,489,614
Net unrealized gains (losses) on investments - net of taxes	94
Net loss	(25,904)
Ending Balance, Amount at Oct. 31, 2018	411,139	$ 14	175,906	(185)	235,404
Ending Balance, Shares at Oct. 31, 2018		32,149,520
Beginning Balance, Amount at Apr. 30, 2018	468,808	$ 15	217,880	(389)	251,302
Beginning Balance, Shares at Apr. 30, 2018		33,396,304
Issuance of shares through employee equity incentive plan, Amount	642	$ 0	642	0	0
Issuance of shares through employee equity incentive plan, Shares		373,126
Stock repurchase, Amount	(44,989)	$ 0	(44,989)	0	0
Stock repurchase, Shares		(1,119,193)
Stock-based compensation expense related to stock awards granted to employees and consultants	15,130	$ 0	15,130	0	0
Net unrealized gains (losses) on investments - net of taxes	178	0	0	178	0
Net loss	(6,877)	0	0	0	(6,877)
Ending Balance, Amount at Jul. 31, 2018	432,892	$ 15	188,663	(211)	244,425
Ending Balance, Shares at Jul. 31, 2018		32,650,237
Issuance of shares through employee equity incentive plan, Amount	117	$ 0	117	0	0
Issuance of shares through employee equity incentive plan, Shares		249,002
Issuance of shares through employee stock purchase plan, Amount	2,318	$ 0	2,318	0	0
Issuance of shares through employee stock purchase plan, Shares		75,472
Stock repurchase, Amount	(30,805)	$ (1)	(30,804)	0	0
Stock repurchase, Shares		(825,191)
Stock-based compensation expense related to stock awards granted to employees and consultants	15,612	$ 0	15,612	0	0
Net unrealized gains (losses) on investments - net of taxes	26	0	0	26	0
Net loss	(9,021)	0	0	0	(9,021)
Ending Balance, Amount at Oct. 31, 2018	411,139	$ 14	175,906	(185)	235,404
Ending Balance, Shares at Oct. 31, 2018		32,149,520
Beginning Balance, Amount at Jan. 31, 2019	$ 419,489	$ 15	188,516	97	230,861
Beginning Balance, Shares at Jan. 31, 2019	32,303,540	32,303,540
Issuance of shares through employee equity incentive plan, Amount	$ 1,520	$ 0	1,520	0	0
Issuance of shares through employee equity incentive plan, Shares		335,301
Issuance of shares through employee stock purchase plan, Amount	3,063	$ 0	3,063	0	0
Issuance of shares through employee stock purchase plan, Shares		99,759
Stock-based compensation expense related to stock awards granted to employees and consultants	15,423	$ 0	15,423	0	0
Net unrealized gains (losses) on investments - net of taxes	254	0	0	254	0
Net loss	(17,311)	0	0	0	(17,311)
Ending Balance, Amount at Apr. 30, 2019	422,438	$ 15	208,522	351	213,550
Ending Balance, Shares at Apr. 30, 2019		32,738,600
Beginning Balance, Amount at Jan. 31, 2019	$ 419,489	$ 15	188,516	97	230,861
Beginning Balance, Shares at Jan. 31, 2019	32,303,540	32,303,540
Stock repurchase, Shares	0
Net unrealized gains (losses) on investments - net of taxes	$ 588
Net loss	(31,811)
Ending Balance, Amount at Oct. 31, 2019	$ 445,240	$ 15	245,490	685	199,050
Ending Balance, Shares at Oct. 31, 2019	33,540,324	33,540,324
Beginning Balance, Amount at Apr. 30, 2019	$ 422,438	$ 15	208,522	351	213,550
Beginning Balance, Shares at Apr. 30, 2019		32,738,600
Issuance of shares through employee equity incentive plan, Amount	988	$ 0	988	0	0
Issuance of shares through employee equity incentive plan, Shares		295,019
Stock-based compensation expense related to stock awards granted to employees and consultants	15,032	$ 0	15,032	0	0
Net unrealized gains (losses) on investments - net of taxes	194	0	0	194	0
Net loss	(10,191)	0	0	0	(10,191)
Ending Balance, Amount at Jul. 31, 2019	428,461	$ 15	224,542	545	203,359
Ending Balance, Shares at Jul. 31, 2019		33,033,619
Issuance of shares through employee equity incentive plan, Amount	2,711	$ 0	2,711	0	0
Issuance of shares through employee equity incentive plan, Shares		428,600
Issuance of shares through employee stock purchase plan, Amount	$ 2,904	$ 0	2,904	0	0
Issuance of shares through employee stock purchase plan, Shares		78,105
Stock repurchase, Shares	0
Stock-based compensation expense related to stock awards granted to employees and consultants	$ 15,333	$ 0	15,333	0	0
Net unrealized gains (losses) on investments - net of taxes	140	0	0	140	0
Net loss	(4,309)	0	0	0	(4,309)
Ending Balance, Amount at Oct. 31, 2019	$ 445,240	$ 15	$ 245,490	$ 685	$ 199,050
Ending Balance, Shares at Oct. 31, 2019	33,540,324	33,540,324

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018
Cash flows from operating activities:
Net loss	$ (31,811)	$ (25,904)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	8,231	5,355
Amortization/accretion of marketable debt securities	(879)	(311)
Stock-based compensation	49,968	44,937
Other non-cash items, net	87	358
Changes in operating assets and liabilities:
Accounts receivable	4,603	(1,123)
Inventories	(1,593)	55
Prepaid expenses and other current assets	857	700
Deferred tax assets	267	(285)
Other assets	(2,974)	(213)
Accounts payable	5,896	(8,681)
Accrued liabilities	3,658	(5,192)
Income taxes payable	(38)	(181)
Deferred revenue	16	140
Lease Liabilities	(2,238)	0
Other long-term liabilities	1,234	843
Net cash provided by operating activities	35,284	10,498
Cash flows from investing activities:
Purchase of investments	(160,988)	(139,816)
Sales of investments	72,773	50,618
Maturities of investments	105,995	40,928
Purchase of property and equipment	(1,425)	(2,380)
Net cash provided by (used in) investing activities	16,355	(50,650)
Cash flows from financing activities:
Stock repurchase	0	(96,419)
Proceeds from exercise of stock options and employee stock purchase plan	9,552	4,722
Payment for intangible asset	(2,930)	(2,483)
Net cash provided by (used in) financing activities	6,622	(94,180)
Net increase (decrease) in cash, cash equivalents and restricted cash	58,261	(134,332)
Cash, cash equivalents and restricted cash at beginning of period	194,058	346,681
Cash, cash equivalents and restricted cash at end of period	252,319	212,349
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,664	1,263
Supplemental disclosure of noncash investing and financing activities:
Unpaid liabilities related to intangible and fixed assets additions	$ 618	$ 299

Organization and Summary of Significant Accounting Policies

9 Months Ended

Oct. 31, 2019

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 leading developer of low-power, high-definition (HD) and Ultra HD video compression and image processing solutions, and computer vision solutions. 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 integrated high-definition video processing, image processing, analysis, audio processing and system functions onto a single chip, delivering exceptional video and image quality, differentiated functionality and low power consumption. Currently the Company is combining advanced computer vision technology with its state-of-the-art video to enable the next generation of intelligent cameras, advanced driver assistance systems (ADAS), electronic mirror, drive recorder, driver/cabin monitoring, autonomous driving and other robotic applications.

The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared by the Company in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and notes normally provided in audited financial statements. The accounting policies are described in the “Notes to Consolidated Financial Statements” in the Annual Report on Form 10-K for the 2019 fiscal year filed with the SEC on March 29, 2019 (the “Form 10-K”) and updated, as necessary, in this Form 10-Q. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from audited financial statements, but does not include all disclosures required by generally accepted accounting principles in the United States (“U.S. GAAP”). In the opinion of management, all adjustments (consisting of normal recurring accruals and adjustments) considered necessary for a fair statement have been included. The results of operations for any interim period are not necessarily indicative of, nor comparable to, the results of operations for any other interim period or for a full fiscal year. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Form 10-K.

Basis of Consolidation

The Company’s fiscal year ends on January 31. The condensed consolidated financial statements of the Company and its subsidiaries have been prepared in conformity with U.S. GAAP. All intercompany transactions and balances have been eliminated upon consolidation.

Use of Estimates

The preparation of condensed 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 of excess and obsolete inventories; (iii) intangible assets and goodwill; (iv) the estimated useful lives of long-lived assets; (v) impairment of long-lived assets and financial instruments; (vi) warranty obligations; (vii) the valuation of stock-based compensation awards and financial instruments; (viii) the probability of performance objectives achievement; (ix) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (x) the recognition and disclosure of contingent liabilities. These estimates and assumptions are based on historical experience and on various other factors which the Company believes to be reasonable under the circumstances. The Company may engage third-party valuation specialists to assist with estimates related to the valuation of financial instruments, assets and stock awards 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 and such differences could be material.

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 one of its distributors, Wintech Microelectronics Co., Ltd., or Wintech, which serves as its non-exclusive sales representative in Asia other than Japan, and directly to one ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationships with these customers could result in a temporary or permanent loss of revenue. Furthermore, any credit issues from these customers could impair their abilities to make timely payment to the Company. See Note 14 for additional information regarding revenue and credit concentration with these customers.

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, marketable debt securities and accounts receivable. The Company maintains its cash primarily in checking 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 losses on deposits of its cash. In order to limit the exposure of each investment, the cash equivalents and marketable debt securities consist primarily of money market funds, asset-backed securities, commercial paper, U.S. government securities and debt securities of corporations which management assesses to be highly liquid. The Company does not hold or issue financial instruments for trading purposes.

The Company performs ongoing credit evaluations of its customers and adjusts credit limits based upon payment history and customers’ credit worthiness. The Company regularly monitors collections and payments from its customers.

Cash Equivalents and Marketable Debt Securities

The Company considers all highly liquid debt security investments with original maturities of less than three months at the time of purchase to be cash equivalents. Debt security investments that are highly liquid with original maturities at the time of purchase greater than three months are considered marketable debt securities.

The Company classifies these investments as “available-for-sale” securities carried at fair value, based on quoted market prices of similar assets, with the unrealized gains or losses reported, net of tax, as a separate component of shareholders’ equity and included in accumulated other comprehensive income in the condensed consolidated balance sheets. The amortization of premiums and accretion of discounts and the realized gains and losses are both recorded in other income, net, in the condensed consolidated statements of operations. The Company reviews its investments for possible other-than-temporary impairments on a regular basis. If any loss on investment is believed to be other-than-temporary, a charge will be recorded and a new cost basis in the investment will be established. In evaluating whether a loss on a security is other-than-temporary, the Company considers the following factors: (i) general market conditions, (ii) the duration and extent to which the fair value is less than cost and (iii) the Company’s intent and ability to hold the investment.

For securities in an unrealized loss position which is deemed to be other-than-temporary, the difference between the security’s then-current amortized cost basis and fair value is separated into (i) the amount of the impairment related to the credit loss (i.e., the credit loss component) and (ii) the amount of the impairment related to all other factors (i.e., the non-credit loss component). The credit loss component is recognized in earnings. The non-credit loss component is recognized in accumulated other comprehensive loss. Due to the relative short term nature of the investments, there have been no other-than-temporary impairments recorded to date.

Restricted Cash

Amounts included in restricted cash represent those required to be set aside to secure certain transactions in a foreign entity. As of October 31, 2019 and January 31, 2019, the restricted cash was immaterial. The following table presents cash, cash equivalents and restricted cash reported on the condensed consolidated balance sheets and the sums are presented on the condensed consolidated statements of cash flows:

	As of
	October 31, 2019		January 31, 2019		October 31, 2018		January 31, 2018
	(in thousands)
Cash and cash equivalents	$	252,310	$	194,047	$	212,338	$	346,672
Restricted cash		9		11		11		9
Total as presented in the consolidated statements of cash flows	$	252,319	$	194,058	$	212,349	$	346,681

Inventories

The Company records inventories at the lower of cost or net realizable value. 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. Any adjustments to reduce the cost of inventories to their net realizable value are recognized in earnings in the current period. Once inventory is written down, a new accounting cost basis is established and, accordingly, any associated reserve is not released until the inventory is sold or scrapped. There were no material inventory losses recognized for the three and nine months ended October 31, 2019 and 2018, respectively.

Noncancelable Internal-Use Software License

The Company accounts for a noncancelable on premise internal-use software license as the acquisition of an intangible asset and the incurrence of a liability to the extent that all or a portion of the software licensing fees are not paid on or before the license acquisition date. The intangible asset and related liability are recorded at net present value and interest expense is recorded over the payment term.

Leases

Effective February 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) Topic 842, Leases, using the alternative transition method with an adjustment to the opening balance in the period of adoption without adjustment of comparative period financial statements. Under this new guidance, the Company recognizes leases as right-of-use (“ROU”) assets and corresponding lease liabilities at the lease commencement date based on the present value of future lease payments, while recognizing lease expenses under straight-line method through the lease term. The Company also elected the other available practical expedients, and has elected not to recognize ROU assets and lease liabilities that arise from short-term (12 months or less) leases and not to reassess the following for existing leases as of February 1, 2019: (i) whether contracts are or contain leases, (ii) lease classification, and (iii) initial direct costs. The Company does not combine lease components with non-lease components, and as a result, the non-lease components are accounted for separately. In determining the present value of lease payments, the Company uses the implicit interest rate if readily determinable. When the implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at the lease commencement date. The Company's leases mainly include its worldwide office facilities which are all classified as operating leases. Certain leases include renewal options that are under the Company's discretion. The renewal options are included in the ROU and liability calculation if it is reasonably certain that the Company will exercise the option. As of February 1, 2019, the Company recognized approximately $8.6 million of ROU assets, net of previously recognized prepaid rent and accrued liabilities, and corresponding lease liabilities of $8.7 million. The Company's finance leases are immaterial as of October 31, 2019 and February 1, 2019, respectively.

Revenue Recognition

Effective February 1, 2018, the Company adopted ASC 606, Revenue from Contracts with Customers. As a result, the Company recognizes product revenue upon shipment and transfer of control to distributors (known as “sell-in” revenue recognition) rather than shipment to the end customers (known as “sell-through” revenue recognition) based on its estimate of the consideration it expects to receive. Revenue recognition is evaluated through the following five steps: (i) identification of the contract, or contracts, with a customer; (ii) identification of the performance obligations in the contract; (iii) determination of the transaction price; (iv) allocation of the transaction price to the performance obligations in the contract; and (v) recognition of revenue when or as a performance obligation is satisfied.

The sale of semiconductor products accounts for the substantial majority of the Company’s consolidated revenue. Sales agreements with customers are renewable periodically and contain terms and conditions with respect to payment, delivery, warranty, supply and other rights. The Company considers an accepted customer purchase order, governed by sales agreement, to be the contract with the customer. For each contract, the Company considers the promise to transfer tangible products to be the identified performance obligation. Product sales contracts may include volume-based tiered pricing or rebates that are fulfilled in cash or product. In determining the transaction price, the Company accounts for the right of returns, cash rebates, commissions and other pricing adjustments as variable consideration and estimates these amounts based on the expected amount to be provided to customers and reduces the revenue recognized. The Company estimates sales returns and rebates based on the Company’s historical patterns of return and pricing credits. As the Company’s standard payment terms are 30 days to 60 days, the contracts have no financing component. Under ASC 606, the Company estimates the total consideration to be received by using the expected value method for each contract, computes weighted average selling price for each unit shipped in cases where there is a material right due to the presence of volume-based tiered pricing, allocates the total consideration between the identified performance obligations, and recognizes revenue when control of its goods and services is transferred to its customers. The Company considers product control to be transferred at shipment or delivery because the Company has a present right to payment at that time, the customer has legal title to the asset, the Company has transferred physical possession of the asset, and the customer has significant risk and rewards of ownership of the asset.

The Company also enters into fixed-price engineering service agreements with certain customers. These agreements may include multiple performance obligations, such as software development services, licensing of intellectual property and post-contract customer support, or PCS. These multiple performance obligations are highly interdependent, highly interrelated, are typically not sold separately and do not have standalone selling prices. They are all inputs to generate one combined output which is incorporating the Company’s SoC into the customer’s product. Accordingly, the Company determines that they are not separately identifiable and shall be treated as a single performance obligation. Customers usually pay based on milestones achieved. Because payments received do not correspond directly with the value of the Company’s performance to date, for fixed-price engineering services arrangements, revenue is recognized using the time-based straight line method, which best depicts the Company’s performance toward complete satisfaction of the performance obligation based on the nature of such professional services. Revenues from engineering service agreements were not material for the three and nine months ended October 31, 2019 and 2018, respectively.

The Company records contract assets when revenue is recognized prior to invoicing. The Company’s contract liabilities are primarily related to the portion of transaction price that exceeds the weighted average selling price for products sold to date under tiered-pricing contracts which contain material rights. These contract liabilities are expected to be recognized over the course of the contract when products are delivered for future pricing below the weighted average selling price of the contract. For the three and nine months ended October 31, 2019 and 2018, the Company did not recognize any material revenue adjustment related to performance obligations satisfied in prior periods released from these contract liabilities. As of October 31, 2019 and January 31, 2019, the contract liabilities were not material. Additionally, the transaction price allocated to unsatisfied, or partially unsatisfied, purchase orders for contracts that are greater than a year was not material as of October 31, 2019 and January 31, 2019, 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.

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, costs of fabrication of masks for prototype products, other development materials costs, depreciation of equipment and tools and allocation of facility costs, net of any research and development grants. As of October 31, 2019, there was approximately $1.2 million of grants recorded in prepaid expenses and other current assets and approximately $2.9 million of grants recorded in other non-current assets in the condensed consolidated balance sheets.

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 its tax positions and tax benefits, the Company considers and evaluates 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 condensed 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 condensed consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the condensed 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, the Company 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 condensed consolidated income statement for the periods in which the adjustment is determined to be required.

Net Income (Loss) Per Ordinary Share

Basic earnings (losses) per share is computed by dividing net income (loss) available to ordinary shareholders by the weighted-average number of ordinary shares outstanding during the period. Diluted earnings (losses) per share is computed by dividing net income (loss) available to ordinary shareholders by the weighted-average number of ordinary shares outstanding during the period increased to include the number of additional ordinary shares that would have been outstanding if the potentially dilutive securities had been issued. Potentially dilutive securities include outstanding stock options, shares to be purchased under the Company’s employee stock purchase plan, unvested restricted stock and restricted stock units. The dilutive effect of potentially dilutive securities is reflected in diluted earnings (losses) per share by application of the treasury stock method.

Comprehensive Income (Loss)

Comprehensive income (loss) includes unrealized gains or losses from available-for-sale securities that are excluded from net income (loss).

Recent Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326), to introduce a new impairment model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses (“ECL”). Under the new model, an entity is required to estimate ECL on available-for-sale (AFS) debt securities only when the fair value is below the amortized cost of the asset and is no longer based on an impairment being “other-than-temporary”. The new model also requires the impairment calculation on an individual security level and requires an entity use present value of cash flows when estimating the ECL. The credit-related losses are required to be recognized through earnings and non-credit related losses are reported in other comprehensive income. In April 2019, the FASB further clarified the scope of the credit losses standard and addressed issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayment. The ASU will be effective for public entities in fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The new guidance will require modified retrospective application to all outstanding instruments, with a cumulative effect adjustment recorded to opening retained earnings as of the beginning of the first period in which the guidance becomes effective. The Company does not believe the adoption of this new guidance will have a material impact on its consolidated financial statements.

In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment, to eliminate the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. This new guidance will be applied prospectively and is effective for annual and interim periods beginning after December 15, 2019. The Company does not believe the adoption of this new guidance will have a material impact on its financial position, results of operations and disclosures.

In August 2018, the FASB issued 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. Under this new guidance, the entities will no longer be required to disclose the amount of and the reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019 and for the interim periods within those fiscal years. Early adoption is permitted. The Company does not believe the adoption of this new guidance will have a material impact on its financial position, results of operations and disclosures.

In August 2018, the FASB issued 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Under this new guidance, the entities are required to capitalize implementation costs related to a hosting arrangement that is a service contract and amortize the costs over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The guidance is effective for fiscal years beginning after December 15, 2019 and for the interim periods within those fiscal years. Early adoption is permitted. The Company does not believe the adoption of this new guidance will have a material impact on its financial position, results of operations and disclosures.

In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 25, Financial Instruments. The new guidance further clarifies that equity instruments without readily determinable fair values for which an entity has elected the measurement alternative should be remeasured to fair value as of the date that an observable transaction occurred. The FASB also amended the guidance to clarify that the nonrecurring fair value disclosure is applicable to equity instruments accounted for under the measurement alternative. The ASU will be effective for public entities in fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted and requires a prospective method for those related to equity securities without readily determinable fair values that are measured using the measurement alternative. The Company does not believe the adoption of this new amendment will have a material impact on its consolidated financial statements.

In November 2019, the FASB issued ASU 2019-08, Compensation – Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606): Codification Improvements – Share-Based Consideration Payable to a Customer. Under this new guidance, share-based payment award issued to a customer should be recorded as a reduction of the transaction price in revenue with an amount measured under the grant-date fair value of the award. Changes in the measurement of the share-based payments after the grant date that are due to the form of the consideration are not included in the transaction price and are recorded elsewhere in the income statement. The award is measured and classified under ASC 718 for its entire life, unless the award is modified after it vests and the grantee is no longer a customer. The new guidance is effective for public entities that have adopted ASU 2018-07 in fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. The Company does not believe the adoption of this new guidance will have an impact on its consolidated financial statements.

Financial Instruments and Fair Value

9 Months Ended

Oct. 31, 2019

Investments All Other Investments [Abstract]

Financial Instruments and Fair Value

2. Financial Instruments and Fair Value

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

	As of October 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	23,595	$	—	$	—		$	23,595
Commercial paper		66,320		—		—			66,320
Corporate bonds		85,890		617		(12	)		86,495
Asset-backed securities		16,516		43		(6	)		16,553
U.S. government securities		16,823		43		—			16,866
Total cash equivalents and marketable debt securities	$	209,144	$	703	$	(18	)	$	209,829

	As of January 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	8,914	$	—	$	—		$	8,914
Certificates of Deposit		7,012		—		—			7,012
Commercial paper		68,233		—		—			68,233
Corporate bonds		87,250		170		(60	)		87,360
Asset-backed securities		11,607		3		(6	)		11,604
U.S. government securities		21,993		3		(13	)		21,983
Total cash equivalents and marketable debt securities	$	205,009	$	176	$	(79	)	$	205,106

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Included in cash equivalents	$	61,348	$	40,245
Included in marketable debt securities		148,481		164,861
Total cash equivalents and marketable debt securities	$	209,829	$	205,106

The contractual maturities of the investments at October 31, 2019 and January 31, 2019 were as follows:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Due within one year	$	153,433	$	151,991
Due within one to three years		56,396		53,115
Total cash equivalents and marketable debt securities	$	209,829	$	205,106

The unrealized losses on the available-for-sale securities were primarily caused by fluctuations in market value and interest rates as a result of the economic environment. As the decline in market value was attributable to changes in market conditions and not credit quality, and because the Company neither intended to sell nor was it more likely than not that it will be required to sell these investments prior to a recovery of par value, the Company did not consider these investments to be other-than temporarily impaired as of October 31, 2019 and January 31, 2019, respectively.

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

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

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

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

The Company measures the fair value of money market funds and certificates of deposit using quoted prices in active markets for identical assets and classifies them within Level 1. The respective fair values of the Company’s investments in other debt securities are obtained based on quoted prices for similar assets in active markets and are classified within Level 2.

The following table presents the fair value of the financial instruments measured on a recurring basis as of October 31, 2019 and January 31, 2019:

	As of October 31, 2019
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	23,595	$	23,595	$	—	$	—
Commercial paper		66,320		—		66,320		—
Corporate bonds		86,495		—		86,495		—
Asset-backed securities		16,553		—		16,553		—
U.S. government securities		16,866		—		16,866		—
Total cash equivalents and marketable debt securities	$	209,829	$	23,595	$	186,234	$	—

	As of January 31, 2019
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	8,914	$	8,914	$	—	$	—
Certificates of Deposit		7,012		7,012		—		—
Commercial paper		68,233		—		68,233		—
Corporate bonds		87,360		—		87,360		—
Asset-backed securities		11,604		—		11,604		—
U.S. government securities		21,983		—		21,983		—
Total cash equivalents and marketable debt securities	$	205,106	$	15,926	$	189,180	$	—

Inventories

9 Months Ended

Oct. 31, 2019

Inventory Disclosure [Abstract]

Inventories

3. Inventories

Inventories at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Work-in-progress	$	11,830	$	9,430
Finished goods		8,015		8,822
Total	$	19,845	$	18,252

Property and Equipment, Net

9 Months Ended

Oct. 31, 2019

Property Plant And Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, Net

Depreciation expense was approximately $0.7 million and $0.6 million for the three months ended October 31, 2019 and 2018, respectively. Depreciation expense was approximately $2.1 million and $1.9 million for the nine months ended October 31, 2019 and 2018, respectively. Property and equipment at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019			January 31, 2019
	(in thousands)
Computer equipment and software	$	10,095		$	9,098
Machinery and equipment		6,162			5,659
Furniture and fixtures		969			969
Leasehold improvements		2,345			2,331
Construction in progress		49			330
		19,620			18,387
Less: accumulated depreciation and amortization		(13,693	)		(11,659	)
Total property and equipment, net	$	5,927		$	6,728

Intangible Assets, Net

9 Months Ended

Oct. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets, Net

5. Intangible Assets, Net

Intangible assets primarily consist of $4.1 million of in-process research and development (“IPR&D”) from the acquisition of VisLab S.r.l., or VisLab, in June 2015 and $4.1 million of noncancelable software licenses, net of amortization expense. Acquired IPR&D is capitalized at fair value and the amortization commences upon completion of the underlying projects. When a project underlying reported IPR&D is completed, the corresponding amount of IPR&D is reclassified as an amortizable purchased intangible asset and is amortized over its estimated useful life. As of October 31, 2019 and January 31, 2019, there was no IPR&D amortized, respectively. The Company will determine the project incorporating the VisLab IPR&D to be completed when a related chip begins mass production to address the level 3 and above advanced driving assistance systems markets.

The Company enters into certain internal-use noncancelable software license agreements with third parties from time-to-time. The licenses have been capitalized as intangible assets, and the corresponding future payments have been recorded as liabilities at net present value. As of October 31, 2019 and January 31, 2019, $2.8 million and $4.9 million was recorded in accrued and other current liabilities, respectively, and $0.7 million and $0.3 million was recorded in other long-term liabilities, respectively, in the condensed consolidated balance sheets.

The carrying amounts of intangible assets as of October 31, 2019 and January 31, 2019 were as follows:

	As of October 31, 2019							As of January 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
	(in thousands)
In-process research and development	$	4,100	$	—		$	4,100	$	4,100	$	—		$	4,100
Internal-use software licenses		15,654		(11,522	)		4,132		14,448		(7,612	)		6,836
Total acquired intangible assets	$	19,754	$	(11,522	)	$	8,232	$	18,548	$	(7,612	)	$	10,936

The amortization expense related to these software licenses was approximately $1.3 million and $1.2 million for the three months ended October 31, 2019 and 2018, respectively. The amortization expense related to these software licenses was approximately $3.9 million and $3.5 million for the nine months ended October 31, 2019 and 2018, respectively. The estimated future amortization expense of these software licenses as of October 31, 2019 is as follows:

	As of
	October 31, 2019
Fiscal Year	(in thousands)
2020 (3 months remaining)	$	1,359
2021		2,099
2022		552
2023		122
2024		—
Thereafter		—
Total future amortization expenses:	$	4,132

IPR&D is required to be tested for impairment at least annually in the fourth fiscal quarter or sooner whenever events or changes in circumstances indicate that the assets may be impaired. There were no intangible asset impairments for the three and nine months ended October 31, 2019 and 2018, respectively.

Accrued and Other Current Liabilities

9 Months Ended

Oct. 31, 2019

Payables And Accruals [Abstract]

Accrued and Other Current Liabilities

6. Accrued and Other Current Liabilities

Accrued and other current liabilities at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Accrued employee compensation	$	14,982	$	10,645
Accrued rebates		247		311
Accrued product development costs		8,017		6,393
Software license liabilities, current		2,839		4,879
Other accrued liabilities		2,362		2,472
Total accrued and other current liabilities	$	28,447	$	24,700

Leases

9 Months Ended

Oct. 31, 2019

Leases [Abstract]

Leases

7. Leases

The Company has entered into various operating leases for its worldwide office buildings and research and development facilities. During the three months ended October 31, 2019, the Company exercised the renewal option to extend its U.S. office lease for a period of 63 months beginning from June 1, 2020 through August 31, 2025 and renewed its Shanghai office lease for another two years beginning from December 1, 2019 to November 30, 2021. The Company accounted these two renewed contracts as lease modifications and recorded an increase to the operating lease right-of-use assets and corresponding operating lease liabilities by approximately $4.0 million, respectively, in the condensed consolidated balance sheets.

The Company also signed a separate lease for additional space for its U.S. office for a period of 56 months beginning from January 1, 2021 through August 31, 2025 and will record it in the balance sheet upon commencement date on January 1, 2021. The total estimated future undiscounted cash payments for this lease are approximately $1.7 million.

In August 2019, VisLab, a wholly-owned subsidiary, was granted a land lease for 35 years with an obligation to construct a building on the land in line with architectural requirements from the lessor in Parma, Italy (“Parma lease”). The Company will be responsible for the costs of construction and occupy the building after completion of construction for the remainder of the lease term. At the end of the lease, the land together with the building and all of the improvements will revert to the lessor. The Parma lease will be recorded in the balance sheet upon completion of the building construction, which is expected to be two years after the lease inception date. Any payments made prior to completion of construction will be recorded as prepayments of the lease in other non-current assets in the condensed consolidated balance sheets. The total estimated future undiscounted cash payments are approximately $2.2 million, of which $1.8 million will be paid in the first two years and the remaining balance of $0.4 million will be paid over the remainder of the lease term.

For the three and nine months ended October 31, 2019, the Company recorded approximately $0.7 million and $2.2 million of operating lease expense, respectively. The Company's short-term leases and finance leases are immaterial as of October 31, 2019.

The cumulative effect of the changes made to the condensed consolidated balance sheet as of February 1, 2019 for the adoption of ASC 842 was as follows:

	Balance as of					Opening Balance as of
	January 31, 2019		Adjustment			February 1, 2019
	(in thousands)
Operating lease right-of-use assets	$	—	$	8,581		$	8,581
Prepaid expenses and other current assets	$	6,206	$	(174	)	$	6,032
Accrued and other current liabilities	$	24,700	$	(279	)	$	24,421
Operating lease liabilities, current	$	—	$	2,534		$	2,534
Operating lease liabilities, non-current	$	—	$	6,152		$	6,152

Supplemental cash flow information related to leases is as follows:

	Three Months Ended		Nine Months Ended
	October 31, 2019		October 31, 2019
	(in thousands)
Cash paid for operating leases included in operating cash flows	$	784	$	2,238
Supplemental non-cash information related to lease liabilities arising from obtaining right-of-use assets	$	82	$	210
Leased assets obtained in exchange for operating lease liabilities arising from lease modifications	$	4,021	$	4,021

As of October 31, 2019, the weighted average remaining lease term is 5.17 years, and the weighted average discount rate is 4.43 percent. Future minimum lease payments for the lease liabilities, excluding the additional space for the U.S. office and the Parma lease described above, are as follows:

	As of
	October 31, 2019
Fiscal Year	(in thousands)
2020 (3 months remaining)	$	633
2021		2,487
2022		2,353
2023		1,644
2024		1,693
Thereafter		2,947
Total future annual minimum lease payments		11,757
Less: interest		(1,077	)
Total lease liabilities	$	10,680

Prior to the adoption of the new leases guidance, future minimum undiscounted lease payments as of January 31, 2019 were as follows:

	As of
	January 31, 2019
Fiscal Year	(in thousands)
2020	$	2,592
2021		1,040
2022		356
2023		143
2024		147
Thereafter		576
Total future annual minimum lease payments	$	4,854

The increased liabilities, as compared to the minimum lease payments as of January 31, 2019, were primarily attributable to a renewal option exercised and lease modifications during the nine months ended October 31, 2019.

Other Long-Term Liabilities

9 Months Ended

Oct. 31, 2019

Other Liabilities Disclosure [Abstract]

Other Long-Term Liabilities

8. Other Long-Term Liabilities

Other long-term liabilities at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Unrecognized tax benefits, including interest	$	7,872	$	6,732
Deferred tax liabilities, non-current		1,293		1,293
Software license liabilities, non-current		660		310
Other long-term liabilities		100		6
Total other long-term liabilities	$	9,925	$	8,341

Capital Stock

9 Months Ended

Oct. 31, 2019

Equity [Abstract]

Capital Stock

9. Capital Stock

Preference shares

After completion of the Company’s initial public offering in 2012, a total of 20,000,000 preference shares, with a $0.00045 par value per share, were authorized. There were no preference shares issued and outstanding as of October 31, 2019 and January 31, 2019, respectively.

Ordinary shares

As of October 31, 2019 and January 31, 2019, a total of 200,000,000 ordinary shares were authorized.

On February 1, 2019, the Company added 1,453,659 ordinary shares to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the 2012 Equity Incentive Plan, or EIP. Pursuant to such provision, for each fiscal year, the number of ordinary shares reserved for issuance under the EIP is automatically increased by a number equal to the lesser of (i) 3,500,000 ordinary shares, (ii) four and one half percent (4.5%) of the aggregate number of ordinary shares outstanding on January 31st of the preceding fiscal year, or (iii) a lesser number of shares that may be determined by the Company’s Board of Directors.

On February 1, 2019, the Company added 403,794 ordinary shares to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the Amended and Restated 2012 Employee Stock Purchase Plan, or ESPP. Pursuant to such provision, for each fiscal year, the number of ordinary shares reserved for issuance under the ESPP is automatically increased by a number equal to the lesser of (i) 1,500,000 ordinary shares, (ii) one and one quarter percent (1.25%) of the aggregate number of ordinary shares outstanding on such date, or (iii) an amount determined by the Company’s Board of Directors or a duly authorized committee of the Board of Directors.

As of October 31, 2019 and January 31, 2019, the following ordinary shares were reserved for future issuance under the EIP and ESPP:

	As of
	October 31, 2019		January 31, 2019
Shares reserved for options, restricted stock and restricted stock units under EIP		6,310,393		5,915,654
Shares reserved for ESPP		2,059,504		1,833,574

Shares repurchased

On June 4, 2018, the Company’s Board of Directors authorized the repurchase of up to $100.0 million of the Company’s ordinary shares over a twelve-month period through June 4, 2019. On May 29, 2019, the Company’s Board of Directors authorized an additional repurchase of up to $50.0 million of the Company’s ordinary shares commencing immediately through June 30, 2020. Repurchases may be made from time-to-time through open market purchases, 10b5-1 plans or privately negotiated transactions subject to market conditions, applicable legal requirements and other relevant factors. The repurchase program does not obligate the Company to acquire any particular amount of ordinary shares, and it may be suspended at any time at the Company’s discretion. The repurchase program is funded using the Company’s working capital and any repurchased shares are recorded as authorized but unissued shares. There were no shares repurchased during the three and nine months ended October 31, 2019, respectively. As of October 31, 2019, there was $50.0 million available for repurchases through June 30, 2020.

Stock-based Compensation

9 Months Ended

Oct. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based Compensation

10. Stock-based Compensation

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

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
	(in thousands)
Stock-based compensation:
Cost of revenue	$	335	$	310	$	922	$	942
Research and development		10,601		9,720		31,306		27,847
Selling, general and administrative		6,372		5,582		17,740		16,148
Total stock-based compensation	$	17,308	$	15,612	$	49,968	$	44,937

During the three and nine months ended October 31, 2019, approximately $2.0 million and $4.2 million of stock-based compensation expense was accrued in the accrued and other current liabilities in the condensed consolidated balance sheets, respectively. As of October 31, 2019, total unrecognized compensation cost related to unvested stock options was $4.1 million and is expected to be recognized over a weighted-average period of 2.61 years. Total unrecognized compensation cost related to unvested restricted stock units was $128.2 million and is expected to be recognized over a weighted-average period of 2.68 years. All restricted stock awards were fully vested as of October 31, 2019.

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

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
Stock Options:
Volatility		52	%		53	%		52	%		54	%
Risk-free interest rate		1.39	%		2.78	%		1.84	%		2.75	%
Expected term (years)	6.09			5.45			6.02				5.40
Dividend yield		0	%		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		46	%		44	%		47	%		45	%
Risk-free interest rate		1.93	%		2.35	%		2.23	%		2.15	%
Expected term (years)	0.5			0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%		0	%

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

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value Of		Remaining		Aggregate
				Weighted-		Average		Options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2019		1,459,064		$	28.31
Granted		57,350			49.79	$	25.06
Exercised		(338,289	)		15.43			$	12,054
Forfeited		(13,306	)		45.65
Expired		(9,751	)		55.95
Outstanding at October 31, 2019		1,155,068			32.71					4.54		$	26,387
Exercisable at October 31, 2019		981,191		$	29.94						3.80	$	25,280

The intrinsic value of options outstanding and exercisable is 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 on October 31, 2019 was $52.63, as reported by The NASDAQ Global Market. The intrinsic value of exercised options is calculated by the difference between the fair market value of the Company’s ordinary shares on the exercise date and the exercise price.

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

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2019		2,395,516		$	48.49
Granted		1,296,053			54.48
Vested		(775,893	)		51.41
Forfeited		(80,496	)		55.50
Unvested at October 31, 2019		2,835,180		$	50.23

As of October 31, 2019, the aggregate intrinsic value of unvested restricted stock units was $149.2 million.

Net Loss Per Ordinary Share

9 Months Ended

Oct. 31, 2019

Earnings Per Share [Abstract]

Net Loss Per Ordinary Share

11. Net Loss Per Ordinary Share

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

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(4,309	)	$	(9,021	)	$	(31,811	)	$	(25,904	)
Denominator:
Weighted-average ordinary shares - basic		33,304,171			32,171,890			32,885,729			32,908,614
Weighted-average ordinary shares - diluted		33,304,171			32,171,890			32,885,729			32,908,614
Net loss per ordinary share:
Basic	$	(0.13	)	$	(0.28	)	$	(0.97	)	$	(0.79	)
Diluted	$	(0.13	)	$	(0.28	)	$	(0.97	)	$	(0.79	)

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

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
Options to purchase ordinary shares		873,515		1,247,117		948,283		1,172,152
Restricted stock and restricted stock units		1,675,570		2,243,272		1,195,320		1,494,860
Employee stock purchase plan		13,672		58,530		11,204		35,204
		2,562,757		3,548,919		2,154,807		2,702,216

Income Taxes

9 Months Ended

Oct. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

The following table provides details of income taxes for the periods indicated:

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
	(in thousands)
Loss before income taxes	$	(5,251	)	$	(8,429	)	$	(29,509	)	$	(23,537	)
Provision (benefit) for income taxes		(942	)		592			2,302			2,367
Effective tax rate	17.9%			(7.0)%			(7.8%)			(10.1%)

The income tax expense decreased for the three and nine months ended October 31, 2019, respectively, as compared to the same periods in the prior fiscal year, primarily due to an increase in tax benefits from excess stock-based compensation deductions, partially offset by a decrease in the proportion of profits generated in lower tax jurisdictions.

The Company files federal and state income tax returns in the United States and in various foreign jurisdictions. The tax years 2013 to 2018 remain open to examination by U.S. federal tax authorities. The tax years 2009 to 2018 remain open to examination by U.S. state tax authorities. The tax years 2013 to 2018 remain open to examination by foreign tax authorities. Fiscal years outside of the normal statute of limitations remain open to audit by tax authorities due to tax attributes generated in those earlier years, which have been carried forward and may be audited in subsequent years when utilized.

The Company regularly assesses the likelihood of adverse outcomes resulting from potential tax examinations to determine the adequacy of its provision for income taxes. These assessments can require considerable estimates and judgments. As of October 31, 2019, the gross amount of unrecognized tax benefits was approximately $40.5 million. If the estimates of income tax liabilities prove to be less than the ultimate assessment, then a further charge to expense could be required. If events occur, and the payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities could result in tax benefits being recognized in the period in which the Company determines the liabilities are no longer necessary. The Company does not anticipate significant changes to its uncertain tax positions during the next twelve months.

On July 27, 2015, the United States Tax Court issued a decision (“Tax Court Decision”) in Altera Corp. v. Commissioner, which concluded that related parties in a cost sharing arrangement are not required to share expenses related to share-based compensation. The Tax Court Decision was appealed by the Commissioner to the Ninth Circuit Court of Appeals (“Ninth Circuit”). On June 7, 2019, a three-judge panel from the Ninth Circuit issued an opinion (“Altera Ninth Circuit Panel Opinion”) that reversed the Tax Court Decision. On July 22, 2019, the taxpayer requested a rehearing before the full Ninth Circuit but was denied on November 12, 2019. The taxpayer may subsequently appeal from the Ninth Circuit to the Supreme Court. The Company will continue to monitor the future developments and potential impacts on its consolidated financial statements.

Segment Reporting

9 Months Ended

Oct. 31, 2019

Segment Reporting [Abstract]

Segment Reporting

14. Segment Reporting

The Company operates in one reportable segment related to the development and sales of low-power, high-definition (HD), Ultra HD video compression, image processing and computer vision solutions. 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. 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 based on bill-to location for the periods indicated:

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
	(in thousands)
Taiwan	$	42,986	$	28,300	$	101,567	$	100,650
Asia Pacific		18,011		20,971		49,745		55,372
Europe		2,264		5,734		9,848		13,191
North America other than United States		2,804		1,531		6,688		5,040
United States		1,857		750		3,672		2,445
Total revenue	$	67,922	$	57,286	$	171,520	$	176,698

As of October 31, 2019, substantially all of the Company’s property and equipment, net, was located in the United States, Asia Pacific region and Europe with approximate net amounts of $1.8 million, $2.8 million and $1.3 million, respectively.

Major Customers

The customers representing 10% or more of revenue and accounts receivable were Wintech and Chicony, which accounted for approximately 63.2% and 15.7% of total revenue for the three months ended October 31, 2019, respectively, and accounted for approximately 59.2% and 17.8% of total revenue for the nine months ended October 31, 2019, respectively. The customers representing 10% or more of revenue and accounts receivable were Wintech and Chicony, which accounted for approximately 49.4% and 22.7% of total revenue for the three months ended October 31, 2018, respectively, and accounted for approximately 57.0% and 16.3% of total revenue for the nine months ended October 31, 2018, respectively. Accounts receivable with Wintech and Chicony were approximately $5.9 million and $10.7 million as of October 31, 2019, respectively. Accounts receivable with Wintech and Chicony were approximately $14.3 million and $6.9 million as of January 31, 2019, respectively.

Organization and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Oct. 31, 2019

Accounting Policies [Abstract]

Organization

The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally.

Basis of Presentation

Basis of Consolidation

Use of Estimates

Concentration of Risk

Cash Equivalents and Marketable Debt Securities

Restricted Cash

	As of
	October 31, 2019		January 31, 2019		October 31, 2018		January 31, 2018
	(in thousands)
Cash and cash equivalents	$	252,310	$	194,047	$	212,338	$	346,672
Restricted cash		9		11		11		9
Total as presented in the consolidated statements of cash flows	$	252,319	$	194,058	$	212,349	$	346,681

Inventories

Noncancelable Internal-Use Software License

Leases

Revenue Recognition

Cost of Revenue

Research and Development

Income Taxes

Net Income (Loss) Per Ordinary Share

Comprehensive Income (Loss)

Comprehensive income (loss) includes unrealized gains or losses from available-for-sale securities that are excluded from net income (loss).

Recent Accounting Pronouncements

Organization and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Oct. 31, 2019

Accounting Policies [Abstract]

Schedule of Cash, Cash Equivalents and Restricted Cash

The following table presents cash, cash equivalents and restricted cash reported on the condensed consolidated balance sheets and the sums are presented on the condensed consolidated statements of cash flows:

	As of
	October 31, 2019		January 31, 2019		October 31, 2018		January 31, 2018
	(in thousands)
Cash and cash equivalents	$	252,310	$	194,047	$	212,338	$	346,672
Restricted cash		9		11		11		9
Total as presented in the consolidated statements of cash flows	$	252,319	$	194,058	$	212,349	$	346,681

Financial Instruments and Fair Value (Tables)

9 Months Ended

Oct. 31, 2019

Investments All Other Investments [Abstract]

Schedule of Available-for-Sale Securities at Fair Value

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

	As of October 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	23,595	$	—	$	—		$	23,595
Commercial paper		66,320		—		—			66,320
Corporate bonds		85,890		617		(12	)		86,495
Asset-backed securities		16,516		43		(6	)		16,553
U.S. government securities		16,823		43		—			16,866
Total cash equivalents and marketable debt securities	$	209,144	$	703	$	(18	)	$	209,829

	As of January 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Money market funds	$	8,914	$	—	$	—		$	8,914
Certificates of Deposit		7,012		—		—			7,012
Commercial paper		68,233		—		—			68,233
Corporate bonds		87,250		170		(60	)		87,360
Asset-backed securities		11,607		3		(6	)		11,604
U.S. government securities		21,993		3		(13	)		21,983
Total cash equivalents and marketable debt securities	$	205,009	$	176	$	(79	)	$	205,106

Schedule of Cash Equivalents and Marketable Debt Securities

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Included in cash equivalents	$	61,348	$	40,245
Included in marketable debt securities		148,481		164,861
Total cash equivalents and marketable debt securities	$	209,829	$	205,106

Summary of Contractual Maturities of Investments

The contractual maturities of the investments at October 31, 2019 and January 31, 2019 were as follows:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Due within one year	$	153,433	$	151,991
Due within one to three years		56,396		53,115
Total cash equivalents and marketable debt securities	$	209,829	$	205,106

Schedule of Fair Value of Financial Instruments Measured on Recurring Basis

The following table presents the fair value of the financial instruments measured on a recurring basis as of October 31, 2019 and January 31, 2019:

	As of October 31, 2019
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	23,595	$	23,595	$	—	$	—
Commercial paper		66,320		—		66,320		—
Corporate bonds		86,495		—		86,495		—
Asset-backed securities		16,553		—		16,553		—
U.S. government securities		16,866		—		16,866		—
Total cash equivalents and marketable debt securities	$	209,829	$	23,595	$	186,234	$	—

	As of January 31, 2019
	Total		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	8,914	$	8,914	$	—	$	—
Certificates of Deposit		7,012		7,012		—		—
Commercial paper		68,233		—		68,233		—
Corporate bonds		87,360		—		87,360		—
Asset-backed securities		11,604		—		11,604		—
U.S. government securities		21,983		—		21,983		—
Total cash equivalents and marketable debt securities	$	205,106	$	15,926	$	189,180	$	—

Inventories (Tables)

9 Months Ended

Oct. 31, 2019

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Work-in-progress	$	11,830	$	9,430
Finished goods		8,015		8,822
Total	$	19,845	$	18,252

Property and Equipment, Net (Tables)

9 Months Ended

Oct. 31, 2019

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019			January 31, 2019
	(in thousands)
Computer equipment and software	$	10,095		$	9,098
Machinery and equipment		6,162			5,659
Furniture and fixtures		969			969
Leasehold improvements		2,345			2,331
Construction in progress		49			330
		19,620			18,387
Less: accumulated depreciation and amortization		(13,693	)		(11,659	)
Total property and equipment, net	$	5,927		$	6,728

Intangible Assets, Net (Tables)

9 Months Ended

Oct. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Summary of Carrying Amounts of Intangible Assets

The carrying amounts of intangible assets as of October 31, 2019 and January 31, 2019 were as follows:

	As of October 31, 2019							As of January 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
	(in thousands)
In-process research and development	$	4,100	$	—		$	4,100	$	4,100	$	—		$	4,100
Internal-use software licenses		15,654		(11,522	)		4,132		14,448		(7,612	)		6,836
Total acquired intangible assets	$	19,754	$	(11,522	)	$	8,232	$	18,548	$	(7,612	)	$	10,936

Summary of Estimated Future Amortization Expense of Software Licenses

The estimated future amortization expense of these software licenses as of October 31, 2019 is as follows:

	As of
	October 31, 2019
Fiscal Year	(in thousands)
2020 (3 months remaining)	$	1,359
2021		2,099
2022		552
2023		122
2024		—
Thereafter		—
Total future amortization expenses:	$	4,132

Accrued and Other Current Liabilities (Tables)

9 Months Ended

Oct. 31, 2019

Payables And Accruals [Abstract]

Schedule of Accrued and Other Current Liabilities

Accrued and other current liabilities at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Accrued employee compensation	$	14,982	$	10,645
Accrued rebates		247		311
Accrued product development costs		8,017		6,393
Software license liabilities, current		2,839		4,879
Other accrued liabilities		2,362		2,472
Total accrued and other current liabilities	$	28,447	$	24,700

Leases (Tables)

9 Months Ended

Oct. 31, 2019

Schedule of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases is as follows:

	Three Months Ended		Nine Months Ended
	October 31, 2019		October 31, 2019
	(in thousands)
Cash paid for operating leases included in operating cash flows	$	784	$	2,238
Supplemental non-cash information related to lease liabilities arising from obtaining right-of-use assets	$	82	$	210
Leased assets obtained in exchange for operating lease liabilities arising from lease modifications	$	4,021	$	4,021

Schedule of Future Minimum Lease Payments for Lease Liabilities Excluding Additional Space for U.S. Office and Parma Lease

	As of
	October 31, 2019
Fiscal Year	(in thousands)
2020 (3 months remaining)	$	633
2021		2,487
2022		2,353
2023		1,644
2024		1,693
Thereafter		2,947
Total future annual minimum lease payments		11,757
Less: interest		(1,077	)
Total lease liabilities	$	10,680

Schedule of Future Minimum Undiscounted Lease Payments

Prior to the adoption of the new leases guidance, future minimum undiscounted lease payments as of January 31, 2019 were as follows:

	As of
	January 31, 2019
Fiscal Year	(in thousands)
2020	$	2,592
2021		1,040
2022		356
2023		143
2024		147
Thereafter		576
Total future annual minimum lease payments	$	4,854

Leases (ASC 842) [Member]

Schedule of Cumulative Effect of the Changes to the Condensed Consolidated Balance Sheet

The cumulative effect of the changes made to the condensed consolidated balance sheet as of February 1, 2019 for the adoption of ASC 842 was as follows:

	Balance as of					Opening Balance as of
	January 31, 2019		Adjustment			February 1, 2019
	(in thousands)
Operating lease right-of-use assets	$	—	$	8,581		$	8,581
Prepaid expenses and other current assets	$	6,206	$	(174	)	$	6,032
Accrued and other current liabilities	$	24,700	$	(279	)	$	24,421
Operating lease liabilities, current	$	—	$	2,534		$	2,534
Operating lease liabilities, non-current	$	—	$	6,152		$	6,152

Other Long-Term Liabilities (Tables)

9 Months Ended

Oct. 31, 2019

Other Liabilities Disclosure [Abstract]

Schedule of Other Long-Term Liabilities

Other long-term liabilities at October 31, 2019 and January 31, 2019 consisted of the following:

	As of
	October 31, 2019		January 31, 2019
	(in thousands)
Unrecognized tax benefits, including interest	$	7,872	$	6,732
Deferred tax liabilities, non-current		1,293		1,293
Software license liabilities, non-current		660		310
Other long-term liabilities		100		6
Total other long-term liabilities	$	9,925	$	8,341

Stock-based Compensation (Tables)

9 Months Ended

Oct. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Classification of Stock-based Compensation

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

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
	(in thousands)
Stock-based compensation:
Cost of revenue	$	335	$	310	$	922	$	942
Research and development		10,601		9,720		31,306		27,847
Selling, general and administrative		6,372		5,582		17,740		16,148
Total stock-based compensation	$	17,308	$	15,612	$	49,968	$	44,937

Weighted-Average Assumptions Used to Estimate Fair Value

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

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
Stock Options:
Volatility		52	%		53	%		52	%		54	%
Risk-free interest rate		1.39	%		2.78	%		1.84	%		2.75	%
Expected term (years)	6.09			5.45			6.02				5.40
Dividend yield		0	%		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		46	%		44	%		47	%		45	%
Risk-free interest rate		1.93	%		2.35	%		2.23	%		2.15	%
Expected term (years)	0.5			0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%		0	%

Stock Option Activities

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

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value Of		Remaining		Aggregate
				Weighted-		Average		Options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2019		1,459,064		$	28.31
Granted		57,350			49.79	$	25.06
Exercised		(338,289	)		15.43			$	12,054
Forfeited		(13,306	)		45.65
Expired		(9,751	)		55.95
Outstanding at October 31, 2019		1,155,068			32.71					4.54		$	26,387
Exercisable at October 31, 2019		981,191		$	29.94						3.80	$	25,280

Restricted Stock and Restricted Stock Units Activities

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

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2019		2,395,516		$	48.49
Granted		1,296,053			54.48
Vested		(775,893	)		51.41
Forfeited		(80,496	)		55.50
Unvested at October 31, 2019		2,835,180		$	50.23

Net Loss Per Ordinary Share (Tables)

9 Months Ended

Oct. 31, 2019

Earnings Per Share [Abstract]

Computation of Basic and Diluted Loss Per Ordinary Share

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

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(4,309	)	$	(9,021	)	$	(31,811	)	$	(25,904	)
Denominator:
Weighted-average ordinary shares - basic		33,304,171			32,171,890			32,885,729			32,908,614
Weighted-average ordinary shares - diluted		33,304,171			32,171,890			32,885,729			32,908,614
Net loss per ordinary share:
Basic	$	(0.13	)	$	(0.28	)	$	(0.97	)	$	(0.79	)
Diluted	$	(0.13	)	$	(0.28	)	$	(0.97	)	$	(0.79	)

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

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

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
Options to purchase ordinary shares		873,515		1,247,117		948,283		1,172,152
Restricted stock and restricted stock units		1,675,570		2,243,272		1,195,320		1,494,860
Employee stock purchase plan		13,672		58,530		11,204		35,204
		2,562,757		3,548,919		2,154,807		2,702,216

Income Taxes (Tables)

9 Months Ended

Oct. 31, 2019

Income Tax Disclosure [Abstract]

Summary of Income Taxes

The following table provides details of income taxes for the periods indicated:

	Three Months Ended October 31,						Nine Months Ended October 31,
	2019			2018			2019			2018
	(in thousands)
Loss before income taxes	$	(5,251	)	$	(8,429	)	$	(29,509	)	$	(23,537	)
Provision (benefit) for income taxes		(942	)		592			2,302			2,367
Effective tax rate	17.9%			(7.0)%			(7.8%)			(10.1%)

Segment Reporting (Tables)

9 Months Ended

Oct. 31, 2019

Segment Reporting [Abstract]

Company's Revenue by Geographic Region Based on Bill-to Location

The following table sets forth the Company’s revenue by geographic region based on bill-to location for the periods indicated:

	Three Months Ended October 31,				Nine Months Ended October 31,
	2019		2018		2019		2018
	(in thousands)
Taiwan	$	42,986	$	28,300	$	101,567	$	100,650
Asia Pacific		18,011		20,971		49,745		55,372
Europe		2,264		5,734		9,848		13,191
North America other than United States		2,804		1,531		6,688		5,040
United States		1,857		750		3,672		2,445
Total revenue	$	67,922	$	57,286	$	171,520	$	176,698

Organization and Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019	Oct. 31, 2018	Jan. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 252,310	$ 194,047	$ 212,338	$ 346,672
Restricted cash	9	11	11	9
Total as presented in the consolidated statements of cash flows	$ 252,319	$ 194,058	$ 212,349	$ 346,681

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Feb. 01, 2019	Jan. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Material inventory losses recognized	$ 0	$ 0	$ 0	$ 0
Right-of-use assets	10,595,000		10,595,000			$ 0
Lease liabilities	10,680,000		10,680,000
Prepaid Expenses and Other Current Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Grants recorded	1,200,000		1,200,000
Other Non-current Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Grants recorded	$ 2,900,000		$ 2,900,000
ASU 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets					$ 8,581,000
Lease liabilities					$ 8,700,000

Financial Instruments and Fair Value - Schedule of Available-for-Sale Securities at Fair Value (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 209,144	$ 205,009
Unrealized Gains	703	176
Unrealized Losses	(18)	(79)
Fair Value	209,829	205,106
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,595	8,914
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	23,595	8,914
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		7,012
Unrealized Gains		0
Unrealized Losses		0
Fair Value		7,012
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	66,320	68,233
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	66,320	68,233
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	85,890	87,250
Unrealized Gains	617	170
Unrealized Losses	(12)	(60)
Fair Value	86,495	87,360
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,516	11,607
Unrealized Gains	43	3
Unrealized Losses	(6)	(6)
Fair Value	16,553	11,604
U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,823	21,993
Unrealized Gains	43	3
Unrealized Losses		(13)
Fair Value	$ 16,866	$ 21,983

Inventories - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Inventory Disclosure [Abstract]
Work-in-progress	$ 11,830	$ 9,430
Finished goods	8,015	8,822
Total	$ 19,845	$ 18,252

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 19,620	$ 18,387
Less: accumulated depreciation and amortization	(13,693)	(11,659)
Total property and equipment, net	5,927	6,728
Computer equipment and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	10,095	9,098
Machinery and equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,162	5,659
Furniture and fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	969	969
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,345	2,331
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 49	$ 330

Intangible Assets, Net - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Jan. 31, 2019	Jun. 25, 2015
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of amortization expense	$ 8,232,000		$ 8,232,000		$ 10,936,000
Accumulated amortization of intangible asset	11,522,000		11,522,000		7,612,000
Liabilities associated with noncancelable internal-use software license at net present value, current	2,839,000		2,839,000		4,879,000
Liabilities associated with noncancelable internal-use software license at net present value, non-current	660,000		660,000		310,000
Impairment of intangible assets	0	$ 0	0	$ 0
IPR&D [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of amortization expense	4,100,000		4,100,000		4,100,000
Accumulated amortization of intangible asset	0		0		0
IPR&D [Member] \| Vis Lab SRL [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired						$ 4,100,000
Internal-use software licenses [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of amortization expense	4,132,000		4,132,000		6,836,000
Accumulated amortization of intangible asset	11,522,000		11,522,000		$ 7,612,000
Amortization expense	$ 1,300,000	$ 1,200,000	$ 3,900,000	$ 3,500,000

Intangible Assets, Net - Summary of Carrying Amounts of Intangible Assets (Detail) - USD ($)	Oct. 31, 2019	Jan. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 19,754,000	$ 18,548,000
Accumulated Amortization	(11,522,000)	(7,612,000)
Net Carrying Amount	8,232,000	10,936,000
In-process research and development [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,100,000	4,100,000
Accumulated Amortization	0	0
Net Carrying Amount	4,100,000	4,100,000
Internal-use software licenses [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	15,654,000	14,448,000
Accumulated Amortization	(11,522,000)	(7,612,000)
Net Carrying Amount	$ 4,132,000	$ 6,836,000

Intangible Assets, Net - Summary of Estimated Future Amortization Expense of Software Licenses (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Finite Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 8,232	$ 10,936
Internal-use software licenses [Member]
Finite Lived Intangible Assets [Line Items]
2020 (3 months remaining)	1,359
2021	2,099
2022	552
2023	122
2024	0
Thereafter	0
Net Carrying Amount	$ 4,132	$ 6,836

Accrued and Other Current Liabilities - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Payables And Accruals [Abstract]
Accrued employee compensation	$ 14,982	$ 10,645
Accrued rebates	247	311
Accrued product development costs	8,017	6,393
Software license liabilities, current	2,839	4,879
Other accrued liabilities	2,362	2,472
Total accrued and other current liabilities	$ 28,447	$ 24,700

Leases - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Aug. 31, 2019	Oct. 31, 2019 USD ($) Contract	Oct. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating leases, existence of options to extend		true
Future undiscounted cash payments		$ 11,757	$ 11,757
Operating lease expense		$ 700	$ 2,200
Weighted-average remaining lease term – operating leases		5 years 2 months 1 day	5 years 2 months 1 day
Weighted-average discount rate – operating leases		4.43%	4.43%
Parma Lease [Member]
Lessee Lease Description [Line Items]
Future undiscounted cash payments		$ 2,200	$ 2,200
Future undiscounted cash payments in first two years		1,800	1,800
Future undiscounted cash payments, paid in remainder of lease term		$ 400	$ 400
Renewed Contract [Member]
Lessee Lease Description [Line Items]
Operating lease number of renewed contracts \| Contract		2
An increase to operating lease right-of-use assets		$ 4,000
An increase to operating lease liabilities		$ 4,000
U.S. [Member] \| Additional Office Space [Member]
Lessee Lease Description [Line Items]
Lease term		56 months	56 months
Commencement date			Jan. 01, 2021
Expiration date			Aug. 31, 2025
Future undiscounted cash payments		$ 1,700	$ 1,700
U.S. [Member] \| Renewed Contract [Member]
Lessee Lease Description [Line Items]
Lease term		63 months	63 months
Commencement date		Jun. 01, 2020
Expiration date		Aug. 31, 2025
Shanghai [Member] \| Renewed Contract [Member]
Lessee Lease Description [Line Items]
Lease term		2 years	2 years
Commencement date		Dec. 01, 2019
Expiration date		Nov. 30, 2021
Italy [Member] \| Building [Member]
Lessee Lease Description [Line Items]
Lease term	35 years
Construction completion period	2 years

Leases - Schedule of Cumulative Effect of Changes to Condensed Consolidated Balance Sheet for Adoption of ASC 842 (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Feb. 01, 2019	Jan. 31, 2019
Leases Disclosure [Line Items]
Operating lease right-of-use assets	$ 10,595		$ 0
Prepaid expenses and other current assets	5,174		6,206
Accrued and other current liabilities	28,447		24,700
Operating lease liabilities, current	2,161		0
Operating lease liabilities, non-current	$ 8,519		$ 0
Leases (ASC 842) [Member]
Leases Disclosure [Line Items]
Operating lease right-of-use assets		$ 8,581
Prepaid expenses and other current assets		6,032
Accrued and other current liabilities		24,421
Operating lease liabilities, current		2,534
Operating lease liabilities, non-current		6,152
Leases (ASC 842) [Member] \| Restatement Adjustment [Member]
Leases Disclosure [Line Items]
Operating lease right-of-use assets		8,581
Prepaid expenses and other current assets		(174)
Accrued and other current liabilities		(279)
Operating lease liabilities, current		2,534
Operating lease liabilities, non-current		$ 6,152

Leases - Schedule of Future Minimum Lease Payments for Lease Liabilities Excluding Additional Space for U.S. Office and Parma Lease (Detail) $ in Thousands	Oct. 31, 2019 USD ($)
Leases [Abstract]
2020 (3 months remaining)	$ 633
2021	2,487
2022	2,353
2023	1,644
2024	1,693
Thereafter	2,947
Total future annual minimum lease payments	11,757
Less: interest	(1,077)
Total lease liabilities	$ 10,680

Leases - Schedule of Future Minimum Undiscounted Lease Payments (Detail) $ in Thousands	Jan. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 2,592
2021	1,040
2022	356
2023	143
2024	147
Thereafter	576
Total future annual minimum lease payments	$ 4,854

Other Long-Term Liabilities - Schedule of Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Other Liabilities Disclosure [Abstract]
Unrecognized tax benefits, including interest	$ 7,872	$ 6,732
Deferred tax liabilities, non-current	1,293	1,293
Software license liabilities, non-current	660	310
Other long-term liabilities	100	6
Total other long-term liabilities	$ 9,925	$ 8,341

Capital Stock - Additional Information (Detail) - USD ($)				3 Months Ended	9 Months Ended
	May 29, 2019	Feb. 01, 2019	Jun. 04, 2018	Oct. 31, 2019	Oct. 31, 2019	Jan. 31, 2019
Class Of Stock [Line Items]
Preference shares, shares authorized				20,000,000	20,000,000	20,000,000
Preference shares, par value				$ 0.00045	$ 0.00045	$ 0.00045
Preference shares, shares issued				0	0	0
Preference shares, shares outstanding				0	0	0
Ordinary shares, shares authorized				200,000,000	200,000,000	200,000,000
Stock repurchased during period, shares				0	0
Amount available under stock repurchase program				$ 50,000,000.0	$ 50,000,000.0
2012 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		1,453,659
2012 Equity Incentive Plan [Member] \| Scenario, plan automatically increased by the lessor of [Member]
Class Of Stock [Line Items]
Annual increase in ordinary shares for available for future issuance		3,500,000
Annual shares increase for future issuance by percentage under 2012 equity incentive plan		4.50%
Amended and Restated 2012 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		403,794
Amended and Restated 2012 Employee Stock Purchase Plan [Member] \| Scenario, plan automatically increased by the lessor of [Member]
Class Of Stock [Line Items]
Annual increase in ordinary shares for available for future issuance		1,500,000
Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan		1.25%
Stock Repurchase Program $100.0 Million Authorization [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorization date			Jun. 04, 2018
Stock repurchase program, period			12 months
Stock repurchase program, expiration date			Jun. 04, 2019
Stock Repurchase Program $100.0 Million Authorization [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program			$ 100,000,000.0
Stock Repurchase Program $50.0 Million Authorization [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorization date	May 29, 2019
Stock repurchase program, expiration date	Jun. 30, 2020
Stock Repurchase Program $50.0 Million Authorization [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program	$ 50,000,000.0

Stock-based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 17,308	$ 15,612	$ 49,968	$ 44,937
Closing price of ordinary shares	$ 52.63		$ 52.63
Accrued and other current liabilities [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 2,000		$ 4,200
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, stock options	4,100		$ 4,100
Weighted average recognition period			2 years 7 months 9 days
Restricted stock units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, restricted stock units	128,200		$ 128,200
Weighted average recognition period			2 years 8 months 4 days
Aggregate intrinsic value of unvested restricted stock units	$ 149,200		$ 149,200
Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award fully vested			Oct. 31, 2019

Stock-based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value (Detail)	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	52.00%	53.00%	52.00%	54.00%
Risk-free interest rate	1.39%	2.78%	1.84%	2.75%
Expected term (years)	6 years 1 month 2 days	5 years 5 months 12 days	6 years 7 days	5 years 4 months 24 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Employee stock purchase plan awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	46.00%	44.00%	47.00%	45.00%
Risk-free interest rate	1.93%	2.35%	2.23%	2.15%
Expected term (years)	6 months	6 months	6 months	6 months
Dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Oct. 31, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding \| shares	1,459,064
Shares, Granted \| shares	57,350
Shares, Exercised \| shares	(338,289)
Shares, Forfeited \| shares	(13,306)
Shares, Expired \| shares	(9,751)
Shares, Outstanding \| shares	1,155,068
Shares, Exercisable \| shares	981,191
Weighted-Average Exercise Price, Outstanding	$ 28.31
Weighted-Average Exercise Price, Granted	49.79
Weighted-Average Exercise Price, Exercised	15.43
Weighted-Average Exercise Price, Forfeited	45.65
Weighted-Average Exercise Price, Expired	55.95
Weighted-Average Exercise Price, Outstanding	32.71
Weighted-Average Exercise Price, Exercisable	29.94
Weighted-Average Grant-date Fair Value, Granted	$ 25.06
Total Intrinsic Value Of Options Exercised \| $	$ 12,054
Weighted-Average Remaining Contractual Term, Outstanding	4 years 6 months 14 days
Weighted-Average Remaining Contractual Term, Exercisable	3 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding \| $	$ 26,387
Aggregate Intrinsic Value, Exercisable \| $	$ 25,280

Stock-based Compensation - Restricted Stock and Restricted Stock Units Activities (Detail) - Restricted stock and restricted stock units [Member]	9 Months Ended
	Oct. 31, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested, beginning balance \| shares	2,395,516
Shares, Granted \| shares	1,296,053
Shares, Vested \| shares	(775,893)
Shares, Forfeited \| shares	(80,496)
Shares, Unvested, ending balance \| shares	2,835,180
Weighted-Average Grant-Date Fair Value, Unvested, beginning balance \| $ / shares	$ 48.49
Weighted-Average Grant-Date Fair Value, Granted \| $ / shares	54.48
Weighted-Average Grant-Date Fair Value, Vested \| $ / shares	51.41
Weighted-Average Grant-Date Fair Value, Forfeited \| $ / shares	55.50
Weighted-Average Grant-Date Fair Value, Unvested, ending balance \| $ / shares	$ 50.23

Net Loss Per Ordinary Share - Computation of Basic and Diluted Loss Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Oct. 31, 2019	Oct. 31, 2018
Numerator:
Net loss	$ (4,309)	$ (10,191)	$ (17,311)	$ (9,021)	$ (6,877)	$ (10,006)	$ (31,811)	$ (25,904)
Denominator:
Weighted-average ordinary shares - basic	33,304,171			32,171,890			32,885,729	32,908,614
Weighted-average ordinary shares - diluted	33,304,171			32,171,890			32,885,729	32,908,614
Net loss per ordinary share:
Basic	$ (0.13)			$ (0.28)			$ (0.97)	$ (0.79)
Diluted	$ (0.13)			$ (0.28)			$ (0.97)	$ (0.79)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

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

+ References + Details

Net Loss Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Loss Per Ordinary Share (Detail) - shares	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	2,562,757	3,548,919	2,154,807	2,702,216
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	873,515	1,247,117	948,283	1,172,152
Restricted stock and restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	1,675,570	2,243,272	1,195,320	1,494,860
Employee stock purchase plan awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	13,672	58,530	11,204	35,204

Income Taxes - Summary of Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Income Tax Disclosure [Abstract]
Loss before income taxes	$ (5,251)	$ (8,429)	$ (29,509)	$ (23,537)
Provision (benefit) for income taxes	$ (942)	$ 592	$ 2,302	$ 2,367
Effective tax rate	17.90%	(7.00%)	(7.80%)	(10.10%)

Income Taxes - Additional Information (Detail) $ in Millions	9 Months Ended
	Oct. 31, 2019 USD ($)
Income Taxes [Line Items]
Unrecognized tax benefits	$ 40.5
U.S. federal tax authorities [Member] \| Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2013
U.S. federal tax authorities [Member] \| Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2018
U.S. state tax authorities [Member] \| Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2009
U.S. state tax authorities [Member] \| Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2018
Foreign tax authorities [Member] \| Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2013
Foreign tax authorities [Member] \| Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year	2018

Commitments and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Oct. 31, 2019	Jan. 31, 2019
Loss Contingencies [Line Items]
Total manufacturing purchase commitments	$ 27,600,000	$ 28,200,000
Indemnification agreement [Member]
Loss Contingencies [Line Items]
Payments under indemnification obligations	0	0
Liabilities recorded under indemnification obligations	$ 0	$ 0

Segment Reporting - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 31, 2018	Oct. 31, 2019 USD ($) Segment	Oct. 31, 2018	Jan. 31, 2019 USD ($)
Concentration Risk [Line Items]
Number of reportable segment \| Segment			1
Property and equipment, net	$ 5,927		$ 5,927		$ 6,728
Accounts receivable	$ 21,609		$ 21,609		26,212
Sales revenue, net [Member] \| Wintech [Member] \| Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue	63.20%	49.40%	59.20%	57.00%
Sales revenue, net [Member] \| Chicony [Member] \| Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue	15.70%	22.70%	17.80%	16.30%
Accounts receivable [Member] \| Wintech [Member] \| Credit concentration risk [Member]
Concentration Risk [Line Items]
Accounts receivable	$ 5,900		$ 5,900		14,300
Accounts receivable [Member] \| Chicony [Member] \| Credit concentration risk [Member]
Concentration Risk [Line Items]
Accounts receivable	10,700		10,700		$ 6,900
United States [Member]
Concentration Risk [Line Items]
Property and equipment, net	1,800		1,800
Asia Pacific [Member]
Concentration Risk [Line Items]
Property and equipment, net	2,800		2,800
Europe [Member]
Concentration Risk [Line Items]
Property and equipment, net	$ 1,300		$ 1,300

Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Revenue from External Customer [Line Items]
Total revenue	$ 67,922	$ 57,286	$ 171,520	$ 176,698
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	42,986	28,300	101,567	100,650
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	18,011	20,971	49,745	55,372
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	2,264	5,734	9,848	13,191
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,804	1,531	6,688	5,040
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,857	$ 750	$ 3,672	$ 2,445

Financial Instruments and Fair Value - Schedule of Cash Equivalents and Marketable Debt Securities (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 209,829	$ 205,106
Included in cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	61,348	40,245
Included in marketable debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 148,481	$ 164,861

Financial Instruments and Fair Value - Summary of Contractual Maturities of Investments (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due within one year	$ 153,433	$ 151,991
Due within one to three years	56,396	53,115
Total cash equivalents and marketable debt securities	$ 209,829	$ 205,106

Financial Instruments and Fair Value - Schedule of Fair Value of Financial Instruments Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Jan. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	$ 209,829	$ 205,106
Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	23,595	8,914
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities		7,012
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	66,320	68,233
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	86,495	87,360
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	16,553	11,604
U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	16,866	21,983
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	23,595	15,926
Level 1 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	23,595	8,914
Level 1 [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities		7,012
Level 1 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 1 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 1 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 1 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	186,234	189,180
Level 2 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 2 [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities		0
Level 2 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	66,320	68,233
Level 2 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	86,495	87,360
Level 2 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	16,553	11,604
Level 2 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	16,866	21,983
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 3 [Member] \| Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 3 [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities		0
Level 3 [Member] \| Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 3 [Member] \| Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 3 [Member] \| Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	0	0
Level 3 [Member] \| U.S. government securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable debt securities	$ 0	$ 0

Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance under EIP and ESPP (Detail) - shares	Oct. 31, 2019	Jan. 31, 2019
EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	6,310,393	5,915,654
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	2,059,504	1,833,574