Ambarella (AMBA) 10-Q 6 Sep 19 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jul. 31, 2019	Sep. 03, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jul. 31, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
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		33,060,050
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

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Current assets:
Cash and cash equivalents	$ 222,693	$ 194,047
Marketable debt securities	153,109	164,861
Accounts receivable, net	27,940	26,212
Inventories	17,376	18,252
Restricted cash	9	11
Prepaid expenses and other current assets	4,491	6,206
Total current assets	425,618	409,589
Property and equipment, net	6,105	6,728
Deferred tax assets, non-current	10,417	10,587
Intangible assets, net	9,008	10,936
Operating lease right-of-use assets, net	7,237	0
Goodwill	26,601	26,601
Other non-current assets	5,246	2,412
Total assets	490,232	466,853
Current liabilities:
Accounts payable	18,912	12,801
Accrued and other current liabilities	24,432	24,700
Operating lease liabilities, current	2,260	0
Income taxes payable	1,083	993
Deferred revenue, current	553	529
Total current liabilities	47,240	39,023
Operating lease liabilities, non-current	5,100	0
Other long-term liabilities	9,431	8,341
Total liabilities	61,771	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 July 31, 2019 and January 31, 2019, respectively	0	0
Ordinary shares, $0.00045 par value per share, 200,000,000 shares authorized at July 31, 2019 and January 31, 2019, respectively; 33,033,619 shares issued and outstanding at July 31, 2019; 32,303,540 shares issued and outstanding at January 31, 2019	15	15
Additional paid-in capital	224,542	188,516
Accumulated other comprehensive income	545	97
Retained earnings	203,359	230,861
Total shareholders’ equity	428,461	419,489
Total liabilities and shareholders' equity	$ 490,232	$ 466,853

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jul. 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	33,033,619	32,303,540
Ordinary shares, shares outstanding	33,033,619	32,303,540

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Income Statement [Abstract]
Revenue	$ 56,410	$ 62,474	$ 103,598	$ 119,412
Cost of revenue	23,973	24,461	43,308	46,507
Gross profit	32,437	38,013	60,290	72,905
Operating expenses:
Research and development	30,420	32,129	63,437	63,793
Selling, general and administrative	12,425	12,566	25,502	25,744
Total operating expenses	42,845	44,695	88,939	89,537
Loss from operations	(10,408)	(6,682)	(28,649)	(16,632)
Other income, net	2,195	732	4,391	1,524
Loss before income taxes	(8,213)	(5,950)	(24,258)	(15,108)
Provision for income taxes	1,978	927	3,244	1,775
Net loss	$ (10,191)	$ (6,877)	$ (27,502)	$ (16,883)
Net loss per share attributable to ordinary shareholders:
Basic	$ (0.31)	$ (0.21)	$ (0.84)	$ (0.51)
Diluted	$ (0.31)	$ (0.21)	$ (0.84)	$ (0.51)
Weighted-average shares used to compute net loss per share attributable to ordinary shareholders:
Basic	32,860,974	33,219,152	32,676,509	33,276,976
Diluted	32,860,974	33,219,152	32,676,509	33,276,976

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (10,191)	$ (6,877)	$ (27,502)	$ (16,883)
Other comprehensive income, net of tax:
Unrealized gains on investments	194	178	448	68
Other comprehensive income, net of tax	194	178	448	68
Comprehensive loss	$ (9,997)	$ (6,699)	$ (27,054)	$ (16,815)

Condensed Consolidated Statem_3

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	68
Net loss	(16,883)
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
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
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	$ 448
Net loss	(27,502)
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	33,033,619
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 repurchase, Shares	0
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	33,033,619

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
Cash flows from operating activities:
Net loss	$ (27,502)	$ (16,883)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5,439	3,565
Amortization/accretion of marketable debt securities	(696)	(106)
Stock-based compensation	32,660	29,325
Other non-cash items, net	87	200
Changes in operating assets and liabilities:
Accounts receivable	(1,728)	2,287
Inventories	876	(7,404)
Prepaid expenses and other current assets	1,541	1,318
Deferred tax assets	170	(118)
Other assets	(2,834)	(279)
Accounts payable	6,111	3,566
Accrued liabilities	(288)	(9,054)
Income taxes payable	90	(412)
Deferred revenue	24	318
Lease Liabilities	(1,454)	0
Other long-term liabilities	923	654
Net cash provided by operating activities	13,419	6,977
Cash flows from investing activities:
Purchase of investments	(91,143)	(39,639)
Sales of investments	32,573	15,120
Maturities of investments	71,395	31,750
Purchase of property and equipment	(954)	(1,977)
Net cash provided by investing activities	11,871	5,254
Cash flows from financing activities:
Stock repurchase	0	(65,614)
Proceeds from exercise of stock options and employee stock purchase plan	5,429	3,672
Payment for intangible asset	(2,075)	(1,672)
Net cash provided by (used in) financing activities	3,354	(63,614)
Net increase (decrease) in cash, cash equivalents and restricted cash	28,644	(51,383)
Cash, cash equivalents and restricted cash at beginning of period	194,058	346,681
Cash, cash equivalents and restricted cash at end of period	222,702	295,298
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,283	1,009
Supplemental disclosure of noncash investing and financing activities:
Unpaid liabilities related to intangible and fixed assets additions	$ 347	$ 286

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jul. 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) and autonomous vehicles. 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 July 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 July 31, 2019 January 31, 2019 July 31, 2018 January 31, 2018 (in thousands) Cash and cash equivalents $ 222,693 $ 194,047 $ 295,289 $ 346,672 Restricted cash 9 11 9 9 Total as presented in the consolidated statements of cash flows $ 222,702 $ 194,058 $ 295,298 $ 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. 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. 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 six months ended July 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 six months ended July 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 July 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 July 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 July 31, 2019, there was approximately $1.2 million of grants recorded in prepaid expenses and other current assets and approximately $2.8 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 im plied 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 e ffective 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.

Financial Instruments and Fair

Financial Instruments and Fair Value	6 Months Ended
	Jul. 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 July 31, 2019 Amortized Unrealized Unrealized Losses Fair Value (in thousands) Money market funds $ 17,409 $ — $ — $ 17,409 Commercial paper 59,934 — — 59,934 Corporate bonds 96,237 525 (4 ) 96,758 Asset-backed securities 14,460 42 (2 ) 14,500 U.S. government securities 19,744 2 (18 ) 19,728 Total cash equivalents and marketable debt securities $ 207,784 $ 569 $ (24 ) $ 208,329 As of January 31, 2019 Amortized 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 July 31, 2019 January (in thousands) Included in cash equivalents $ 55,220 $ 40,245 Included in marketable debt securities 153,109 164,861 Total cash equivalents and marketable debt securities $ 208,329 $ 205,106 The contractual maturities of the investments at July 31, 2019 and January 31, 2019 were as follows: As of July 31, 2019 January (in thousands) Due within one year $ 155,351 $ 151,991 Due within one to three years 52,978 53,115 Total cash equivalents and marketable debt securities $ 208,329 $ 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 July 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 July 31, 2019 and January 31, 2019: As of July 31, 2019 Total Level 1 Level 2 Level 3 (in thousands) Money market funds $ 17,409 $ 17,409 $ — $ — Commercial paper 59,934 — 59,934 — Corporate bonds 96,758 — 96,758 — Asset-backed securities 14,500 — 14,500 — U.S. government securities 19,728 — 19,728 — Total cash equivalents and marketable debt securities $ 208,329 $ 17,409 $ 190,920 $ — 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

Inventories	6 Months Ended
	Jul. 31, 2019
Inventory Disclosure [Abstract]
Inventories	3. Inventories Inventories at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Work-in-progress $ 9,854 $ 9,430 Finished goods 7,522 8,822 Total $ 17,376 $ 18,252

Property and Equipment, Net

Property and Equipment, Net	6 Months Ended
	Jul. 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 July 31, 2019 and 2018, respectively. Depreciation expense was approximately $1.4 million and $1.3 million for the six months ended July 31, 2019 and 2018, respectively. Property and equipment at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Computer equipment and software $ 9,641 $ 9,098 Machinery and equipment 6,098 5,659 Furniture and fixtures 969 969 Leasehold improvements 2,343 2,331 Construction in progress 50 330 19,101 18,387 Less: accumulated depreciation and amortization (12,996 ) (11,659 ) Total property and equipment, net $ 6,105 $ 6,728

Intangible Assets

Intangible Assets	6 Months Ended
	Jul. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	5. Intangible Assets 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, 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 July 31, 2019 and January 31, 2019, $3.3 million and $4.9 million was recorded in accrued and other current liabilities, respectively, and $0.5 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 July 31, 2019 and January 31, 2019 were as follows : As of July 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 15,104 (10,196 ) 4,908 14,448 (7,612 ) 6,836 Total acquired intangible assets $ 19,204 $ (10,196 ) $ 9,008 $ 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 July 31, 2019 and 2018, respectively. The amortization expense related to these software licenses was approximately $2.6 million and $2.3 million for the six months ended July 31, 2019 and 2018, respectively. The estimated future amortization expense of these software licenses as of July 31, 2019 is as follows: As of July 31, 2019 Fiscal Year (in thousands) 2020 (6 months remaining) $ 2,629 2021 1,911 2022 368 2023 — 2024 — Thereafter — Total future amortization expenses: $ 4,908 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 six months ended July 31, 2019 and 2018, respectively.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	6 Months Ended
	Jul. 31, 2019
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	6. Accrued and Other Current Liabilities Accrued and other current liabilities at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Accrued employee compensation $ 12,705 $ 10,645 Accrued rebates 302 311 Accrued product development costs 6,156 6,393 Software license liabilities, current 3,317 4,879 Other accrued liabilities 1,952 2,472 Total accrued and other current liabilities $ 24,432 $ 24,700

Leases

Leases	6 Months Ended
	Jul. 31, 2019
Leases [Abstract]
Leases	7. Leases The Company has entered into operating leases for its worldwide office buildings and research and development facilities. The leases expire at various dates through fiscal year 2028, some of which include options to extend the lease for up to 3 years. For the three and six months ended July 31, 2019, the Company recorded approximately $0.7 million and $1.5 million of operating lease expense, respectively. The Company's short-term leases and finance leases are immaterial . 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, (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 Six Months Ended July 31, 2019 July 31, 2019 (in thousands) Cash paid for operating leases included in operating cash flows $ 727 $ 1,454 Supplemental non-cash information related to lease liabilities arising from obtaining right-of-use assets $ 63 $ 128 As of July 31, 2019, the weighted average remaining lease term is 4.15 years, and the weighted average discount rate is 5.00 percent. Future minimum lease payments for the operating lease liabilities are as follows : As of July 31, 2019 Fiscal Year (in thousands) 2020 (6 months remaining) $ 1,346 2021 2,143 2022 1,783 2023 1,566 2024 491 Thereafter 514 Total future annual minimum lease payments 7,843 Less: interest (483 ) Total lease liabilities $ 7,360 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 a result of the adoption of ASC 842 were attributable to a renewal option reasonably certain to be exercised. In August 2019, the Company entered into several lease agreements for its office facilities. See Note 15, "Subsequent Events" in the Notes to Condensed Consolidated Financial Statements for more details about the lease liabilities.

Other Long-Term Liabilities

Other Long-Term Liabilities	6 Months Ended
	Jul. 31, 2019
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	8. Other Long-Term Liabilities Other long-term liabilities at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Unrecognized tax benefits, including interest $ 7,654 $ 6,732 Deferred tax liabilities, non-current 1,293 1,293 Software license liabilities, non-current 478 310 Other long-term liabilities 6 6 Total other long-term liabilities $ 9,431 $ 8,341

Capital Stock

Capital Stock	6 Months Ended
	Jul. 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 July 31, 2019 and January 31, 2019, respectively. Ordinary shares As of July 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 July 31, 2019 and January 31, 2019, the following ordinary shares were reserved for future issuance under the EIP and ESPP: As of July 31, 2019 January 31, 2019 Shares reserved for options, restricted stock and restricted stock units under EIP 6,738,993 5,915,654 Shares reserved for ESPP 2,137,609 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 six months ended July 31, 2019, respectively. As of July 31, 2019, there was $50.0 million available for repurchases through June 30, 2020.

Stock-based Compensation

Stock-based Compensation	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Stock-based compensation: Cost of revenue $ 320 $ 317 $ 587 $ 632 Research and development 10,501 9,367 20,705 18,127 Selling, general and administrative 5,379 5,446 11,368 10,566 Total stock-based compensation $ 16,200 $ 15,130 $ 32,660 $ 29,325 During the three and six months ended July 31, 2019, approximately $1.2 million and $2.2 million of stock-based compensation expense was accrued in the accrued and other current liabilities in the condensed consolidated balance sheets, respectively. As of July 31, 2019, total unrecognized compensation cost related to unvested stock options was $3.8 million and is expected to be recognized over a weighted-average period of 2.55 years. Total unrecognized compensation cost related to unvested restricted stock units was $96.2 million and is expected to be recognized over a weighted-average period of 2.42 years. Total unrecognized compensation cost related to unvested restricted stock awards was $0.1 million and is expected to be recognized over a weighted-average period of 0.13 years. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 Stock Options: Volatility 52 % 55 % 52 % 55 % Risk-free interest rate 1.95 % 2.77 % 2.31 % 2.73 % Expected term (years) 6.09 5.38 5.95 5.36 Dividend yield 0 % 0 % 0 % 0 % Employee stock purchase plan awards: Volatility — — 48 % 46 % Risk-free interest rate — — 2.52 % 1.95 % Expected term (years) — — 0.5 0.5 Dividend yield — — 0 % 0 % The following table summarizes stock option activities for the period indicated: Option Outstanding Weighted- Total Average Weighted- Value Of Remaining Aggregate Weighted- Average Options Contractual Intrinsic Average Grant-date Exercised Term Value Shares Exercise Fair Value (in (in years) (in Outstanding at January 31, 2019 1,459,064 $ 28.31 Granted 28,300 41.07 $ 21.00 Exercised (163,886 ) 15.30 $ 4,493 Forfeited (11,508 ) 45.29 Expired (9,045 ) 56.55 Outstanding at July 31, 2019 1,302,925 29.87 4.31 $ 30,053 Exercisable at July 31, 2019 1,130,044 $ 27.35 3.64 $ 29,049 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 July 31, 2019 was $49.95, 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 455,822 47.47 Vested (506,269 ) 52.59 Forfeited (47,522 ) 51.49 Unvested at July 31, 2019 2,297,547 $ 47.32 As of July 31, 2019, the aggregate intrinsic value of unvested restricted stock and restricted stock units was $114.8 million.

Net Loss Per Ordinary Share

Net Loss Per Ordinary Share	6 Months Ended
	Jul. 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 Six 2019 2018 2019 2018 (in thousands, except share and per share data) Numerator: Net loss $ (10,191 ) $ (6,877 ) $ (27,502 ) $ (16,883 ) Denominator: Weighted-average ordinary shares - basic 32,860,974 33,219,152 32,676,509 33,276,976 Weighted-average ordinary shares - diluted 32,860,974 33,219,152 32,676,509 33,276,976 Net loss per ordinary share: Basic $ (0.31 ) $ (0.21 ) $ (0.84 ) $ (0.51 ) Diluted $ (0.31 ) $ (0.21 ) $ (0.84 ) $ (0.51 ) 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 Options to purchase ordinary shares 968,274 1,077,045 985,667 1,134,670 Restricted stock and restricted stock units 984,234 1,245,210 955,195 1,120,654 Employee stock purchase plan 2,472 7,202 9,971 23,542 1,954,980 2,329,457 1,950,833 2,278,866

Income Taxes

Income Taxes	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Loss before income taxes $ (8,213 ) $ (5,950 ) $ (24,258 ) $ (15,108 ) Provision for income taxes 1,978 927 3,244 1,775 Effective tax rate (24.1)% (15.6)% (13.4)% (11.7)% The income tax expense increased for the three and six months ended July 31, 2019, respectively, as compared to the same periods in the prior fiscal year, primarily due to an increase in non-deductible stock-based compensation, as well as a decrease in the proportion of profits generated in lower tax jurisdictions and losses incurred in jurisdictions for which the Company was not able to recognize the related tax benefit. 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 July 31, 2019, the gross amount of unrecognized tax benefits was approximately $38.7 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 th e 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 rehear ing before the full Ninth Circuit and 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.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jul. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Contract Manufacturer Commitments The Company’s components and products are procured and built by independent contract manufacturers based on sales forecasts. These forecasts include estimates of future demand, historical trends, analysis of sales and marketing activities, and adjustment of overall market conditions. The Company regularly issues purchase orders to independent contract manufacturers which are cancelable upon agreement between the Company and the third-party manufacturers. As of July 31, 2019 and January 31, 2019, total manufacturing purchase commitments were approximately $41.3 million and $28.2 million, respectively. The increased purchase commitments are associated with inventory requirements during the rest of the current fiscal year. Indemnification The Company, from time to time, in the normal course of business, indemnifies certain vendors with whom it enters into contractual relationships. The Company has agreed to hold the other party harmless against third-party claims in connection with the Company’s future products. The Company also indemnifies certain customers against third-party claims related to certain intellectual property matters. It is not possible to determine the maximum potential amount of liability under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances that are likely to be involved in each particular claim. The Company has not made payments under these obligations, and no liabilities have been recorded for these obligations in the condensed consolidated balance sheets as of July 31, 2019 and January 31, 2019, respectively.

Segment Reporting

Segment Reporting	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Taiwan $ 30,981 $ 39,144 $ 58,581 $ 72,350 Asia Pacific 17,246 18,045 31,734 34,401 Europe 4,101 2,875 7,584 7,457 North America other than United States 3,001 1,503 3,884 3,509 United States 1,081 907 1,815 1,695 Total revenue $ 56,410 $ 62,474 $ 103,598 $ 119,412 As of July 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 $1.9 million, $2.9 million and $1.3 million, respectively. As of January 31, 2019, the net amount of these fixed assets located in these regions was approximately $2.1 million, $3.2 million and $1.4 million, respectively. Major Customers The customers representing 10% or more of revenue and accounts receivable were Wintech and Chicony, which accounted for approximately 54.9% and 20.5% of total revenue for the three months ended July 31, 2019, respectively, and accounted for approximately 56.5% and 19.1% of total revenue for the six months ended July 31, 2019, respectively. The customers representing 10% or more of revenue and accounts receivable were Wintech and Chicony, which accounted for approximately 62.7% and 15.0% of total revenue for the three months ended July 31, 2018, respectively, and accounted for approximately 60.6% and 13.2% of total revenue for the six months ended July 31, 2018, respectively. Accounts receivable with Wintech and Chicony were approximately $9.3 million and $11.7 million as of July 31, 2019, respectively. Accounts receivable with Wintech and Chicony were approximately $14.3 million and $6.9 million as of January 31, 2019, respectively.

Subsequent Events

Subsequent Events	6 Months Ended
	Jul. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events In August 2019, the Company entered into an agreement to extend the lease of its current headquarters facility comprised of 47,015 square feet located in Santa Clara, California for a term of 63 months from June 1, 2020 through August 31, 2025. The Company will also lease an additional 11,722 square feet of office space at the same location from January 1, 2021 through August 31, 2025. In addition, the Company entered into a new lease agreement for its Shanghai office facility comprised of approximately 20,602 square feet for a period of two years from December 1, 2019 to November 30, 2021. Lastly, the Company’s subsidiary VisLab S.r.l. entered into an obligation to build an office facility in Parma, Italy which the company will lease for 35 years after construction. The total estimated future undiscounted cash payments were approximately $9.4 million for the Santa Clara leases, $1.5 million for Shanghai office lease and $2.4 million for Parma obligation.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jul. 31, 2019
Accounting Policies [Abstract]
Organization	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) and autonomous vehicles. The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally.
Basis of Presentation	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	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	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	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	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	Restricted Cash Amounts included in restricted cash represent those required to be set aside to secure certain transactions in a foreign entity. As of July 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 July 31, 2019 January 31, 2019 July 31, 2018 January 31, 2018 (in thousands) Cash and cash equivalents $ 222,693 $ 194,047 $ 295,289 $ 346,672 Restricted cash 9 11 9 9 Total as presented in the consolidated statements of cash flows $ 222,702 $ 194,058 $ 295,298 $ 346,681
Inventories	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.
Noncancelable Internal-Use Software License	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	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.
Revenue Recognition	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 six months ended July 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 six months ended July 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 July 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 July 31, 2019 and January 31, 2019, respectively.
Cost of Revenue	Cost of Revenue Cost of revenue includes cost of materials, cost associated with packaging and assembly, testing and shipping, cost of personnel, stock-based compensation, logistics and quality assurance, warranty cost, royalty expense, write-downs of inventories and allocation of overhead.
Research and Development	Research and Development Research and development costs are expensed as incurred and consist primarily of personnel costs, product development costs, which include engineering services, development software and hardware tools, license fees, 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 July 31, 2019, there was approximately $1.2 million of grants recorded in prepaid expenses and other current assets and approximately $2.8 million of grants recorded in other non-current assets in the condensed consolidated balance sheets.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements or tax returns. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company applies authoritative guidance for the accounting for uncertainty in income taxes. The guidance requires that tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. Upon estimating 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	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) Comprehensive income (loss) includes unrealized gains or losses from available-for-sale securities that are excluded from net income (loss).
Recent Accounting Pronouncements	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 im plied 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 e ffective 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.

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jul. 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 July 31, 2019 January 31, 2019 July 31, 2018 January 31, 2018 (in thousands) Cash and cash equivalents $ 222,693 $ 194,047 $ 295,289 $ 346,672 Restricted cash 9 11 9 9 Total as presented in the consolidated statements of cash flows $ 222,702 $ 194,058 $ 295,298 $ 346,681

Financial Instruments and Fai_2

Financial Instruments and Fair Value (Tables)	6 Months Ended
	Jul. 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 July 31, 2019 Amortized Unrealized Unrealized Losses Fair Value (in thousands) Money market funds $ 17,409 $ — $ — $ 17,409 Commercial paper 59,934 — — 59,934 Corporate bonds 96,237 525 (4 ) 96,758 Asset-backed securities 14,460 42 (2 ) 14,500 U.S. government securities 19,744 2 (18 ) 19,728 Total cash equivalents and marketable debt securities $ 207,784 $ 569 $ (24 ) $ 208,329 As of January 31, 2019 Amortized 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 July 31, 2019 January (in thousands) Included in cash equivalents $ 55,220 $ 40,245 Included in marketable debt securities 153,109 164,861 Total cash equivalents and marketable debt securities $ 208,329 $ 205,106
Summary of Contractual Maturities of Investments	The contractual maturities of the investments at July 31, 2019 and January 31, 2019 were as follows: As of July 31, 2019 January (in thousands) Due within one year $ 155,351 $ 151,991 Due within one to three years 52,978 53,115 Total cash equivalents and marketable debt securities $ 208,329 $ 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 July 31, 2019 and January 31, 2019: As of July 31, 2019 Total Level 1 Level 2 Level 3 (in thousands) Money market funds $ 17,409 $ 17,409 $ — $ — Commercial paper 59,934 — 59,934 — Corporate bonds 96,758 — 96,758 — Asset-backed securities 14,500 — 14,500 — U.S. government securities 19,728 — 19,728 — Total cash equivalents and marketable debt securities $ 208,329 $ 17,409 $ 190,920 $ — 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)

Inventories (Tables)	6 Months Ended
	Jul. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventories at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Work-in-progress $ 9,854 $ 9,430 Finished goods 7,522 8,822 Total $ 17,376 $ 18,252

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	6 Months Ended
	Jul. 31, 2019
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Computer equipment and software $ 9,641 $ 9,098 Machinery and equipment 6,098 5,659 Furniture and fixtures 969 969 Leasehold improvements 2,343 2,331 Construction in progress 50 330 19,101 18,387 Less: accumulated depreciation and amortization (12,996 ) (11,659 ) Total property and equipment, net $ 6,105 $ 6,728

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Jul. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Carrying Amounts of Intangible Assets	The carrying amounts of intangible assets as of July 31, 2019 and January 31, 2019 were as follows : As of July 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 15,104 (10,196 ) 4,908 14,448 (7,612 ) 6,836 Total acquired intangible assets $ 19,204 $ (10,196 ) $ 9,008 $ 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 July 31, 2019 is as follows: As of July 31, 2019 Fiscal Year (in thousands) 2020 (6 months remaining) $ 2,629 2021 1,911 2022 368 2023 — 2024 — Thereafter — Total future amortization expenses: $ 4,908

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	6 Months Ended
	Jul. 31, 2019
Payables And Accruals [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Accrued employee compensation $ 12,705 $ 10,645 Accrued rebates 302 311 Accrued product development costs 6,156 6,393 Software license liabilities, current 3,317 4,879 Other accrued liabilities 1,952 2,472 Total accrued and other current liabilities $ 24,432 $ 24,700

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jul. 31, 2019
Schedule of Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases is as follows: Three Months Ended Six Months Ended July 31, 2019 July 31, 2019 (in thousands) Cash paid for operating leases included in operating cash flows $ 727 $ 1,454 Supplemental non-cash information related to lease liabilities arising from obtaining right-of-use assets $ 63 $ 128
Schedule of Future Minimum Lease Payments for Operating Lease Liabilities	As of July 31, 2019, the weighted average remaining lease term is 4.15 years, and the weighted average discount rate is 5.00 percent. Future minimum lease payments for the operating lease liabilities are as follows : As of July 31, 2019 Fiscal Year (in thousands) 2020 (6 months remaining) $ 1,346 2021 2,143 2022 1,783 2023 1,566 2024 491 Thereafter 514 Total future annual minimum lease payments 7,843 Less: interest (483 ) Total lease liabilities $ 7,360
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, (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 (Ta

Other Long-Term Liabilities (Tables)	6 Months Ended
	Jul. 31, 2019
Other Liabilities Disclosure [Abstract]
Schedule of Other Long-Term Liabilities	Other long-term liabilities at July 31, 2019 and January 31, 2019 consisted of the following: As of July 31, 2019 January (in thousands) Unrecognized tax benefits, including interest $ 7,654 $ 6,732 Deferred tax liabilities, non-current 1,293 1,293 Software license liabilities, non-current 478 310 Other long-term liabilities 6 6 Total other long-term liabilities $ 9,431 $ 8,341

Capital Stock (Tables)

Capital Stock (Tables)	6 Months Ended
	Jul. 31, 2019
Equity [Abstract]
Schedule of Ordinary Shares Reserved for Future Issuance under EIP and ESPP	As of July 31, 2019 and January 31, 2019, the following ordinary shares were reserved for future issuance under the EIP and ESPP: As of July 31, 2019 January 31, 2019 Shares reserved for options, restricted stock and restricted stock units under EIP 6,738,993 5,915,654 Shares reserved for ESPP 2,137,609 1,833,574

Stock-based Compensation (Table

Stock-based Compensation (Tables)	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Stock-based compensation: Cost of revenue $ 320 $ 317 $ 587 $ 632 Research and development 10,501 9,367 20,705 18,127 Selling, general and administrative 5,379 5,446 11,368 10,566 Total stock-based compensation $ 16,200 $ 15,130 $ 32,660 $ 29,325
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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 Stock Options: Volatility 52 % 55 % 52 % 55 % Risk-free interest rate 1.95 % 2.77 % 2.31 % 2.73 % Expected term (years) 6.09 5.38 5.95 5.36 Dividend yield 0 % 0 % 0 % 0 % Employee stock purchase plan awards: Volatility — — 48 % 46 % Risk-free interest rate — — 2.52 % 1.95 % Expected term (years) — — 0.5 0.5 Dividend yield — — 0 % 0 %
Stock Option Activities	The following table summarizes stock option activities for the period indicated: Option Outstanding Weighted- Total Average Weighted- Value Of Remaining Aggregate Weighted- Average Options Contractual Intrinsic Average Grant-date Exercised Term Value Shares Exercise Fair Value (in (in years) (in Outstanding at January 31, 2019 1,459,064 $ 28.31 Granted 28,300 41.07 $ 21.00 Exercised (163,886 ) 15.30 $ 4,493 Forfeited (11,508 ) 45.29 Expired (9,045 ) 56.55 Outstanding at July 31, 2019 1,302,925 29.87 4.31 $ 30,053 Exercisable at July 31, 2019 1,130,044 $ 27.35 3.64 $ 29,049
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 455,822 47.47 Vested (506,269 ) 52.59 Forfeited (47,522 ) 51.49 Unvested at July 31, 2019 2,297,547 $ 47.32

Net Loss Per Ordinary Share (Ta

Net Loss Per Ordinary Share (Tables)	6 Months Ended
	Jul. 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 Six 2019 2018 2019 2018 (in thousands, except share and per share data) Numerator: Net loss $ (10,191 ) $ (6,877 ) $ (27,502 ) $ (16,883 ) Denominator: Weighted-average ordinary shares - basic 32,860,974 33,219,152 32,676,509 33,276,976 Weighted-average ordinary shares - diluted 32,860,974 33,219,152 32,676,509 33,276,976 Net loss per ordinary share: Basic $ (0.31 ) $ (0.21 ) $ (0.84 ) $ (0.51 ) Diluted $ (0.31 ) $ (0.21 ) $ (0.84 ) $ (0.51 )
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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 Options to purchase ordinary shares 968,274 1,077,045 985,667 1,134,670 Restricted stock and restricted stock units 984,234 1,245,210 955,195 1,120,654 Employee stock purchase plan 2,472 7,202 9,971 23,542 1,954,980 2,329,457 1,950,833 2,278,866

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Loss before income taxes $ (8,213 ) $ (5,950 ) $ (24,258 ) $ (15,108 ) Provision for income taxes 1,978 927 3,244 1,775 Effective tax rate (24.1)% (15.6)% (13.4)% (11.7)%

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jul. 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 July 31, Six Months Ended July 31, 2019 2018 2019 2018 (in thousands) Taiwan $ 30,981 $ 39,144 $ 58,581 $ 72,350 Asia Pacific 17,246 18,045 31,734 34,401 Europe 4,101 2,875 7,584 7,457 North America other than United States 3,001 1,503 3,884 3,509 United States 1,081 907 1,815 1,695 Total revenue $ 56,410 $ 62,474 $ 103,598 $ 119,412

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019	Jul. 31, 2018	Jan. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 222,693	$ 194,047	$ 295,289	$ 346,672
Restricted cash	9	11	9	9
Total as presented in the consolidated statements of cash flows	$ 222,702	$ 194,058	$ 295,298	$ 346,681

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 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	7,237,000		7,237,000			$ 0
Lease liabilities	7,360,000		7,360,000
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	$ 2,800,000		$ 2,800,000
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 Fai_3

Financial Instruments and Fair Value - Schedule of Available-for-Sale Securities at Fair Value (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 207,784	$ 205,009
Unrealized Gains	569	176
Unrealized Losses	(24)	(79)
Fair Value	208,329	205,106
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	17,409	8,914
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	17,409	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	59,934	68,233
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	59,934	68,233
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	96,237	87,250
Unrealized Gains	525	170
Unrealized Losses	(4)	(60)
Fair Value	96,758	87,360
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,460	11,607
Unrealized Gains	42	3
Unrealized Losses	(2)	(6)
Fair Value	14,500	11,604
U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,744	21,993
Unrealized Gains	2	3
Unrealized Losses	(18)	(13)
Fair Value	$ 19,728	$ 21,983

Financial Instruments and Fai_4

Financial Instruments and Fair Value - Schedule of Cash Equivalents and Marketable Debt Securities (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 208,329	$ 205,106
Included in cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	55,220	40,245
Included in marketable debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 153,109	$ 164,861

Financial Instruments and Fai_5

Financial Instruments and Fair Value - Summary of Contractual Maturities of Investments (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due within one year	$ 155,351	$ 151,991
Due within one to three years	52,978	53,115
Total cash equivalents and marketable debt securities	$ 208,329	$ 205,106

Financial Instruments and Fai_6

Financial Instruments and Fair Value - Schedule of Fair Value of Financial Instruments Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jul. 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	$ 208,329	$ 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	17,409	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	59,934	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	96,758	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	14,500	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	19,728	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	17,409	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	17,409	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	190,920	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	59,934	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	96,758	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	14,500	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	19,728	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

Inventories - Schedule of Inven

Inventories - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Inventory Disclosure [Abstract]
Work-in-progress	$ 9,854	$ 9,430
Finished goods	7,522	8,822
Total	$ 17,376	$ 18,252

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation of property and equipment	$ 0.7	$ 0.6	$ 1.4	$ 1.3

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 19,101	$ 18,387
Less: accumulated depreciation and amortization	(12,996)	(11,659)
Total property and equipment, net	6,105	6,728
Computer equipment and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,641	9,098
Machinery and equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,098	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	2,343	2,331
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 50	$ 330

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018	Jan. 31, 2019	Jun. 25, 2015
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of amortization expense	$ 9,008,000		$ 9,008,000		$ 10,936,000
Accumulated amortization of intangible asset	10,196,000		10,196,000		7,612,000
Liabilities associated with noncancelable internal-use software license at net present value, current	3,317,000		3,317,000		4,879,000
Liabilities associated with noncancelable internal-use software license at net present value, non-current	478,000		478,000		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	4,908,000		4,908,000		6,836,000
Accumulated amortization of intangible asset	10,196,000		10,196,000		$ 7,612,000
Amortization expense	$ 1,300,000	$ 1,200,000	$ 2,600,000	$ 2,300,000

Intangible Assets - Summary of

Intangible Assets - Summary of Carrying Amounts of Intangible Assets (Detail) - USD ($)	Jul. 31, 2019	Jan. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 19,204,000	$ 18,548,000
Accumulated Amortization	(10,196,000)	(7,612,000)
Net Carrying Amount	9,008,000	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	15,104,000	14,448,000
Accumulated Amortization	(10,196,000)	(7,612,000)
Net Carrying Amount	$ 4,908,000	$ 6,836,000

Intangible Assets - Summary o_2

Intangible Assets - Summary of Estimated Future Amortization Expense of Software Licenses (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Finite Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 9,008	$ 10,936
Internal-use software licenses [Member]
Finite Lived Intangible Assets [Line Items]
2020 (6 months remaining)	2,629
2021	1,911
2022	368
2023	0
2024	0
Thereafter	0
Net Carrying Amount	$ 4,908	$ 6,836

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Payables And Accruals [Abstract]
Accrued employee compensation	$ 12,705	$ 10,645
Accrued rebates	302	311
Accrued product development costs	6,156	6,393
Software license liabilities, current	3,317	4,879
Other accrued liabilities	1,952	2,472
Total accrued and other current liabilities	$ 24,432	$ 24,700

Leases - Additional Information

Leases - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2019USD ($)	Jul. 31, 2019USD ($)
Leases [Abstract]
Lease, year of expiration		The leases expire at various dates through fiscal year 2028
Operating leases, existence of options to extend		true
Operating leases, options to extend description		some of which include options to extend the lease for up to 3 years.
Operating leases, extended term	3 years	3 years
Operating lease expense	$ 0.7	$ 1.5
Weighted-average remaining lease term – operating leases	4 years 1 month 24 days	4 years 1 month 24 days
Weighted-average discount rate – operating leases	5.00%	5.00%

Leases - Schedule of Cumulative

Leases - Schedule of Cumulative Effect of Changes to Condensed Consolidated Balance Sheet for Adoption of ASC 842 (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Feb. 01, 2019	Jan. 31, 2019
Leases Disclosure [Line Items]
Operating lease right-of-use assets	$ 7,237		$ 0
Prepaid expenses and other current assets	4,491		6,206
Accrued and other current liabilities	24,432		24,700
Operating lease liabilities, current	2,260		0
Operating lease liabilities, non-current	$ 5,100		$ 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 Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jul. 31, 2019	Jul. 31, 2019
Leases [Abstract]
Cash paid for operating leases included in operating cash flows	$ 727	$ 1,454
Supplemental non-cash information related to lease liabilities arising from obtaining right-of-use assets	$ 63	$ 128

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments for Operating Lease Liabilities (Detail) $ in Thousands	Jul. 31, 2019USD ($)
Leases [Abstract]
2020 (6 months remaining)	$ 1,346
2021	2,143
2022	1,783
2023	1,566
2024	491
Thereafter	514
Total future annual minimum lease payments	7,843
Less: interest	(483)
Total lease liabilities	$ 7,360

Leases - Schedule of Future M_2

Leases - Schedule of Future Minimum Undiscounted Lease Payments (Detail) $ in Thousands	Jan. 31, 2019USD ($)
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 - S

Other Long-Term Liabilities - Schedule of Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Other Liabilities Disclosure [Abstract]
Unrecognized tax benefits, including interest	$ 7,654	$ 6,732
Deferred tax liabilities, non-current	1,293	1,293
Software license liabilities, non-current	478	310
Other long-term liabilities	6	6
Total other long-term liabilities	$ 9,431	$ 8,341

Capital Stock - Additional Info

Capital Stock - Additional Information (Detail) - USD ($)	May 29, 2019	Feb. 01, 2019	Jun. 04, 2018	Jul. 31, 2019	Jul. 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	$ 50,000,000
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. 4, 2018
Stock repurchase program, period			12 months
Stock repurchase program, expiration date			Jun. 4, 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
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

Capital Stock - Schedule of Ord

Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance under EIP and ESPP (Detail) - shares	Jul. 31, 2019	Jan. 31, 2019
EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	6,738,993	5,915,654
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved	2,137,609	1,833,574

Stock-based Compensation - Clas

Stock-based Compensation - Classification of Stock-based Compensation (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Stock-based compensation:
Total stock-based compensation	$ 16,200	$ 15,130	$ 32,660	$ 29,325
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	320	317	587	632
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	10,501	9,367	20,705	18,127
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 5,379	$ 5,446	$ 11,368	$ 10,566

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 16,200	$ 15,130	$ 32,660	$ 29,325
Closing price of ordinary shares	$ 49.95		$ 49.95
Accrued and other current liabilities [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 1,200		$ 2,200
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, stock options	3,800		$ 3,800
Weighted average recognition period			2 years 6 months 18 days
Restricted stock units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, restricted stock units	96,200		$ 96,200
Weighted average recognition period			2 years 5 months 1 day
Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average recognition period			1 month 17 days
Total unrecognized compensation cost, restricted stock awards	100		$ 100
Restricted Stock and Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value of unvested restricted stock and restricted stock units	$ 114,800		$ 114,800

Stock-based Compensation - Weig

Stock-based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value (Detail)	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	52.00%	55.00%	52.00%	55.00%
Risk-free interest rate	1.95%	2.77%	2.31%	2.73%
Expected term (years)	6 years 1 month 2 days	5 years 4 months 17 days	5 years 11 months 12 days	5 years 4 months 9 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			48.00%	46.00%
Risk-free interest rate			2.52%	1.95%
Expected term (years)	0 years	0 years	6 months	6 months
Dividend yield			0.00%	0.00%

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jul. 31, 2019USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding | shares	1,459,064
Shares, Granted | shares	28,300
Shares, Exercised | shares	(163,886)
Shares, Forfeited | shares	(11,508)
Shares, Expired | shares	(9,045)
Shares, Outstanding | shares	1,302,925
Shares, Exercisable | shares	1,130,044
Weighted-Average Exercise Price, Outstanding	$ 28.31
Weighted-Average Exercise Price, Granted	41.07
Weighted-Average Exercise Price, Exercised	15.30
Weighted-Average Exercise Price, Forfeited	45.29
Weighted-Average Exercise Price, Expired	56.55
Weighted-Average Exercise Price, Outstanding	29.87
Weighted-Average Exercise Price, Exercisable	27.35
Weighted-Average Grant-date Fair Value, Granted	$ 21
Total Intrinsic Value Of Options Exercised | $	$ 4,493
Weighted-Average Remaining Contractual Term, Outstanding	4 years 3 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	3 years 7 months 20 days
Aggregate Intrinsic Value, Outstanding | $	$ 30,053
Aggregate Intrinsic Value, Exercisable | $	$ 29,049

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock and Restricted Stock Units Activities (Detail) - Restricted stock and restricted stock units [Member]	6 Months Ended
	Jul. 31, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested, beginning balance | shares	2,395,516
Shares, Granted | shares	455,822
Shares, Vested | shares	(506,269)
Shares, Forfeited | shares	(47,522)
Shares, Unvested, ending balance | shares	2,297,547
Weighted-Average Grant-Date Fair Value, Unvested, beginning balance | $ / shares	$ 48.49
Weighted-Average Grant-Date Fair Value, Granted | $ / shares	47.47
Weighted-Average Grant-Date Fair Value, Vested | $ / shares	52.59
Weighted-Average Grant-Date Fair Value, Forfeited | $ / shares	51.49
Weighted-Average Grant-Date Fair Value, Unvested, ending balance | $ / shares	$ 47.32

Net Loss Per Ordinary Share - C

Net Loss Per Ordinary Share - Computation of Basic and Diluted Loss Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2018	Apr. 30, 2018	Jul. 31, 2019	Jul. 31, 2018
Numerator:
Net loss	$ (10,191)	$ (17,311)	$ (6,877)	$ (10,006)	$ (27,502)	$ (16,883)
Denominator:
Weighted-average ordinary shares - basic	32,860,974		33,219,152		32,676,509	33,276,976
Weighted-average ordinary shares - diluted	32,860,974		33,219,152		32,676,509	33,276,976
Net loss per ordinary share:
Basic	$ (0.31)		$ (0.21)		$ (0.84)	$ (0.51)
Diluted	$ (0.31)		$ (0.21)		$ (0.84)	$ (0.51)

Net Loss Per Ordinary Share - W

Net Loss Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Loss Per Ordinary Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	1,954,980	2,329,457	1,950,833	2,278,866
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	968,274	1,077,045	985,667	1,134,670
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	984,234	1,245,210	955,195	1,120,654
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	2,472	7,202	9,971	23,542

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Income Tax Disclosure [Abstract]
Loss before income taxes	$ (8,213)	$ (5,950)	$ (24,258)	$ (15,108)
Provision for income taxes	$ 1,978	$ 927	$ 3,244	$ 1,775
Effective tax rate	(24.10%)	(15.60%)	(13.40%)	(11.70%)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) $ in Millions	6 Months Ended
	Jul. 31, 2019USD ($)
Income Taxes [Line Items]
Unrecognized tax benefits	$ 38.7
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 -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jul. 31, 2019	Jan. 31, 2019
Loss Contingencies [Line Items]
Total manufacturing purchase commitments	$ 41,300,000	$ 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

Segment Reporting - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019USD ($)	Jul. 31, 2018	Jul. 31, 2019USD ($)Segment	Jul. 31, 2018	Jan. 31, 2019USD ($)
Concentration Risk [Line Items]
Number of reportable segment | Segment			1
Property and equipment, net	$ 6,105		$ 6,105		$ 6,728
Accounts receivable	$ 27,940		$ 27,940		26,212
Sales revenue, net [Member] | Wintech [Member] | Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue	54.90%	62.70%	56.50%	60.60%
Sales revenue, net [Member] | Chicony [Member] | Customer concentration risk [Member]
Concentration Risk [Line Items]
Percentage of revenue	20.50%	15.00%	19.10%	13.20%
Accounts receivable [Member] | Wintech [Member] | Credit concentration risk [Member]
Concentration Risk [Line Items]
Accounts receivable	$ 9,300		$ 9,300		14,300
Accounts receivable [Member] | Chicony [Member] | Credit concentration risk [Member]
Concentration Risk [Line Items]
Accounts receivable	11,700		11,700		6,900
United States [Member]
Concentration Risk [Line Items]
Property and equipment, net	1,900		1,900		2,100
Asia Pacific [Member]
Concentration Risk [Line Items]
Property and equipment, net	2,900		2,900		3,200
Europe [Member]
Concentration Risk [Line Items]
Property and equipment, net	$ 1,300		$ 1,300		$ 1,400

Segment Reporting - Company's R

Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Revenue from External Customer [Line Items]
Total revenue	$ 56,410	$ 62,474	$ 103,598	$ 119,412
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	30,981	39,144	58,581	72,350
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	17,246	18,045	31,734	34,401
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	4,101	2,875	7,584	7,457
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	3,001	1,503	3,884	3,509
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,081	$ 907	$ 1,815	$ 1,695

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ in Thousands	1 Months Ended	6 Months Ended
	Aug. 31, 2019USD ($)ft²	Jul. 31, 2019USD ($)
Subsequent Event [Line Items]
Operating leases, existence of options to extend		true
Future undiscounted cash payments		$ 7,843
Subsequent Event [Member] | Parma Obligation [Member]
Subsequent Event [Line Items]
Future undiscounted cash payments	$ 2,400
Subsequent Event [Member] | California [Member]
Subsequent Event [Line Items]
Lease term	63 months
Operating leases, existence of options to extend	true
Area of office space | ft²	47,015
Commencement date	Jun. 1, 2020
Expiration date	Aug. 31, 2025
Additional area of office space | ft²	11,722
Subsequent Event [Member] | Shanghai [Member]
Subsequent Event [Line Items]
Lease term	2 years
Area of office space | ft²	20,602
Commencement date	Dec. 1, 2019
Expiration date	Nov. 30, 2021
Future undiscounted cash payments	$ 1,500
Subsequent Event [Member] | Italy [Member] | Office Facility [Member]
Subsequent Event [Line Items]
Lease term	35 years
Subsequent Event [Member] | Santa Clara [Member]
Subsequent Event [Line Items]
Future undiscounted cash payments	$ 9,400