Pure Storage (PSTG) 10-Q 8 Jun 18 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Apr. 30, 2018	May 31, 2018
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 30, 2018
Document Fiscal Year Focus	2,019
Document Fiscal Period Focus	Q1
Trading Symbol	PSTG
Entity Registrant Name	Pure Storage, Inc.
Entity Central Index Key	1,474,432
Current Fiscal Year End Date	--01-31
Entity Filer Category	Large Accelerated Filer
Class A
Entity Common Stock, Shares Outstanding (in shares)		173,431,705
Class B
Entity Common Stock, Shares Outstanding (in shares)		57,454,048

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018	[1]
Current assets:
Cash and cash equivalents	$ 735,140	$ 244,057
Marketable securities	362,817	353,289
Accounts receivable, net of allowance of $1,062 and $999 as of January 31, 2018 and April 30, 2018	195,926	243,001
Inventory	38,540	34,497
Deferred commissions, current	20,122	21,088
Prepaid expenses and other current assets	35,652	47,552
Total current assets	1,388,197	943,484
Property and equipment, net	94,280	89,142
Intangible assets, net	4,681	5,057
Deferred income taxes, non-current	1,175	1,060
Restricted cash	16,499	14,763
Deferred commissions, non-current	65,922	66,225
Other assets, non-current	5,305	4,264
Total assets	1,576,059	1,123,995
Current liabilities:
Accounts payable	63,994	84,420
Accrued compensation and benefits	30,778	59,898
Accrued expenses and other liabilities	25,629	26,829
Deferred revenue, current	199,622	191,229
Liability related to early exercised stock options	0	320
Total current liabilities	320,023	362,696
Convertible senior notes, net	430,253	0
Deferred revenue, non-current	188,992	182,873
Other liabilities, non-current	5,171	4,025
Total liabilities	944,439	549,594
Commitments and contingencies (Note 6)
Stockholders’ equity:
Preferred stock, par value of $0.0001 per share— 20,000 shares authorized as of January 31, 2018 and April 30, 2018; no shares issued and outstanding as of January 31, 2018 and April 30, 2018	0	0
Class A and Class B common stock, par value of $0.0001 per share— 2,250,000 (Class A 2,000,000, Class B 250,000) shares authorized as of January 31, 2018 and April 30, 2018; 220,979 (Class A 129,502, Class B 91,477) and 229,596 (Class A 164,207, Class B 65,389) shares issued and outstanding as of January 31, 2018 and April 30, 2018	23	22
Additional paid-in capital	1,602,121	1,479,883
Accumulated other comprehensive loss	(2,633)	(1,917)
Accumulated deficit	(967,891)	(903,587)
Total stockholders’ equity	631,620	574,401
Total liabilities and stockholders’ equity	$ 1,576,059	$ 1,123,995
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018	[1]
Accounts receivable, allowance	$ 999	$ 1,062
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,250,000,000	2,250,000,000
Common stock, shares issued (in shares)	229,596,000	220,979,000
Common stock, shares outstanding (in shares)	229,596,000	220,979,000
Class A
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	164,207,114	129,502,000
Common stock, shares outstanding (in shares)	164,207,114	129,502,000
Class B
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	65,389,256	91,477,000
Common stock, shares outstanding (in shares)	65,389,256	91,477,000
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	[1]
Revenue:
Product	$ 195,449	$ 142,850
Support subscription	60,496	39,795
Total revenue	255,945	182,645
Cost of revenue:
Product	66,420	46,645
Support subscription	23,210	16,903
Total cost of revenue	89,630	63,548
Gross profit	166,315	119,097
Operating expenses:
Research and development	78,492	65,428
Sales and marketing	122,367	91,763
General and administrative	27,330	20,096
Total operating expenses	228,189	177,287
Loss from operations	(61,874)	(58,190)
Other income (expense), net	(999)	1,995
Loss before provision for income taxes	(62,873)	(56,195)
Provision for income taxes	1,431	964
Net loss	$ (64,304)	$ (57,159)	[2],[3]
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.29)	$ (0.28)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	223,768	205,783
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	[3]
Statement of Comprehensive Income [Abstract]
Net loss	$ (64,304)	$ (57,159)	[1],[2]
Other comprehensive income (loss):
Change in unrealized net gain (loss) on available-for-sale securities	(716)	117
Comprehensive loss	$ (65,020)	$ (57,042)
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows $ in Thousands	3 Months Ended
	Apr. 30, 2018USD ($)	Apr. 30, 2017USD ($)	[1]
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (64,304)	$ (57,159)	[2],[3]
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	16,417	14,825
Amortization of debt discount and debt issuance costs	1,455	0
Stock-based compensation expense	43,955	32,219
Other	152	451
Changes in operating assets and liabilities:
Accounts receivable, net	47,143	36,571
Inventory	(4,429)	(16,105)
Deferred commissions	1,269	(1,367)
Prepaid expenses and other current assets	11,111	(3,944)
Accounts payable	(18,802)	(3,982)
Accrued compensation and other liabilities	(29,881)	(24,194)
Deferred revenue	14,510	8,384
Net cash provided by (used in) operating activities	18,596	(14,301)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(22,296)	(12,769)
Purchases of marketable securities	(81,702)	(55,976)
Sales of marketable securities	10,454	5,384
Maturities of marketable securities	61,023	46,321
Net cash used in investing activities	(32,521)	(17,040)
CASH FLOWS FROM FINANCING ACTIVITIES
Net proceeds from exercise of stock options	9,614	2,257
Proceeds from issuance of common stock under employee stock purchase plan	19,698	14,166
Proceeds from issuance of convertible senior notes, net of issuance costs	562,062	0
Payment for purchase of capped calls	(64,630)	0
Repurchase of common stock	(20,000)	0
Net cash provided by financing activities	506,744	16,423
Net increase (decrease) in cash, cash equivalents and restricted cash	492,819	(14,918)
Cash, cash equivalents and restricted cash, beginning of period	258,820	196,409
Cash, cash equivalents and restricted cash, end of period	751,639	181,491
CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD:
Cash and cash equivalents	735,140	168,757
Restricted cash	16,499	12,734
Cash, cash equivalents and restricted cash, end of period	751,639	181,491
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	1,839	790
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION
Property and equipment purchased but not yet paid	8,316	9,685
Vesting of early exercised stock options	$ 320	$ 298
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Business Overview

Business Overview	3 Months Ended
	Apr. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Overview	Business Overview Organization and Description of Business Pure Storage, Inc. (the Company, we, us, or other similar pronouns) was originally incorporated in the state of Delaware in October 2009 under the name OS76, Inc. In January 2010, we changed our name to Pure Storage, Inc. We are headquartered in Mountain View, California and have wholly owned subsidiaries throughout the world. We empower innovators to build a better world with data. Our data platform replaces storage systems designed for mechanical disk with all-flash systems optimized end-to-end for solid-state memory. Our Pure1 cloud-based support and management platform simplifies storage administration, while real-time scanning enables us to find and fix issues before they have an impact. Our business model replaces the traditional forklift upgrade cycle with Evergreen Storage subscriptions to hardware and software innovation, support and maintenance.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Apr. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Principles of Consolidation The condensed consolidated financial statements include the accounts of the company and our wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Unaudited Interim Consolidated Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) and applicable rules and regulations of the Securities and Exchange Commission (the SEC) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended January 31, 2018 . In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year 2019 or any future period. Certain prior period amounts have been adjusted as a result of adoption of new accounting pronouncements. Refer to " Recently Adopted Accounting Pronouncements" below for further information. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the financial statements and accompanying notes. Actual results could differ from these estimates. Such estimates include, but are not limited to, the determination of standalone selling price for revenue arrangements with multiple performance obligations, useful lives of intangible assets, property and equipment and deferred sales commissions, fair values of stock-based awards, provision for income taxes including related reserves, and contingent liabilities, among others. Management bases its estimates on historical experience and on various other assumptions which management believes to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Restricted Cash Restricted cash is comprised of cash collateral related to our leases and for a vendor corporate credit card program. As of January 31, 2018 and April 30, 2018 , we had restricted cash of $14.8 million and $16.5 million on the condensed consolidated balance sheets. Marketable Securities We classify our marketable securities as available-for-sale at the time of purchase and reevaluate such classification at each balance sheet date. We may sell these securities at any time for use in current operations even if they have not yet reached maturity. As a result, we classify our securities, including those with maturities beyond twelve months, as current assets in the accompanying condensed consolidated balance sheets. We carry these securities at fair value and record unrealized gains and losses, in other comprehensive income (loss), which is reflected as a component of stockholders’ equity. We evaluate our securities to assess whether those with unrealized loss positions are other than temporarily impaired. We consider impairments to be other than temporary if they are related to deterioration in credit risk or if it is likely we will sell the securities before the recovery of their cost basis. Realized gains and losses from the sale of marketable securities and declines in value deemed to be other than temporary are determined on the specific identification method. To date, there have been no declines in value deemed to be other than temporary in any of our securities. Realized gains and losses are reported in other income (expense), net in the condensed consolidated statements of operations. Deferred Commissions Deferred commissions consist of incremental costs paid to our sales force to obtain customer contracts. Deferred commissions related to product revenues are recognized upon transfer of control to customers and deferred commissions related to support subscription revenue are amortized over an expected useful life of six years. We determine the expected useful life based on an estimated benefit period by evaluating our technology development life cycle, expected customer relationship period, and other factors. We classify deferred commissions as current and non-current on our condensed consolidated balance sheets based on the timing of when we expect to recognize the expense. Amortization of deferred commissions is included in sales and marketing expense in the condensed consolidated statements of operations. Changes in total deferred commissions during the period presented are as follows (in thousands): Three Months Ended Beginning balance as of January 31, 2018 (as adjusted) $ 87,313 Additions 15,421 Recognition of deferred commissions (16,690 ) Ending balance as of April 30, 2018 $ 86,044 Of the $86.0 million total deferred commissions balance as of April 30, 2018 , we expect to recognize approximately 23% as commission expense over the next 12 months and the remainder thereafter. There was no impairment loss in relation to capitalized commissions for the three months ended April 30, 2017 and 2018 . Deferred Revenue Deferred revenue primarily consists of amounts that have been invoiced but that have not yet been recognized as revenue and consists of performance obligations pertaining to support subscription services. The current portion of deferred revenue represents the amounts that are expected to be recognized as revenue within one year of the condensed consolidated balance sheet dates. Changes in total deferred revenue during the three months ended April 30, 2018 are as follows (in thousands): Three Months Ended Beginning balance as of January 31, 2018 (as adjusted) $ 374,102 Additions 75,271 Recognition of deferred revenue (60,759 ) Ending balance as of April 30, 2018 $ 388,614 During the three months ended April 30, 2017 , we recognized $43.0 million in revenue pertaining to deferred revenue as of January 31, 2017 . During the three months ended April 30, 2018 , we recognized $55.6 million in revenue pertaining to deferred revenue as of January 31, 2018 . Of the $388.6 million remaining performance obligations as of April 30, 2018, we expect to recognize approximately 51% as revenue over the next 12 months and the remainder thereafter. Substantially all of our contracted but not invoiced performance obligations are subject to cancellation and, therefore, are not considered in our remaining performance obligations. Revenue Recognition We derive revenue from two sources: (1) product revenue which includes hardware and embedded software and (2) support subscription revenue which includes customer support, hardware maintenance, and software upgrades on a when-and-if-available basis. Our product revenue is derived from the sale of storage hardware and operating system software that is integrated into the hardware. We typically recognize product revenue upon transfer of control to our customers. Products are typically shipped directly by us to customers, and our channel partners do not stock our inventory. Our support subscription revenue is derived from the sale of support subscription, which includes the right to receive unspecified software upgrades and enhancements on a when-and-if-available basis, bug fixes, parts replacement services related to the hardware, as well as access to our cloud-based management and support platform. Revenue related to support subscription is recognized ratably over the contractual term, which generally ranges from one to six years and represents our performance obligations period. The vast majority of our products are sold with support subscription agreements, which typically commence upon transfer of control of the corresponding products to our customers. Costs to service the support subscription are expensed as incurred. In addition, our Evergreen Storage program provides our customers who continually maintain active support subscription agreements for three years with an included controller refresh with each additional three year support subscription renewal. In accordance with revenue recognition guidance, the controller refresh represents an additional performance obligation and the allocated revenue is recognized in the period in which these controllers are shipped. We recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration we expect to be entitled in exchange for those goods or services. This is achieved through applying the following five-step approach: • Identification of the contract, or contracts, with a customer • Identification of the performance obligations in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligations in the contract • Recognition of revenue when, or as, we satisfy a performance obligation When applying this five-step approach, we apply judgment in determining the customer's ability and intention to pay, which is based on a variety of factors including the customer's historical payment experience and/or published credit and financial information pertaining to the customer. To the extent a customer contract includes multiple promised goods or services, we determine whether promised goods or services are capable of being distinct in the context of the contract to be accounted for as a combined performance obligation. We allocate transaction price to each performance obligation for contracts that contain multiple performance obligations based on a relative standalone selling price, taking into account available information such as market conditions and internally approved pricing guidelines related to performance obligations. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB), issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09 or ASC 606), requiring an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASC 606 supersedes nearly all existing revenue recognition guidance under U.S. GAAP upon its effective date. The standard permits two methods of adoptions: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of applying the standard recognized at the date of application (cumulative catch-up transition method). We adopted the standard using the full retrospective method beginning February 1, 2018, for the year ending January 31, 2019, and our historical financial information for the years ended January 31, 2017 and 2018 has been adjusted to conform to the new standard. The most significant impact of the standard related to the removal of limitation on contingent revenue, resulting in an increase in product revenue and a decrease in support subscription revenue. In addition, the adoption of ASC 606 also resulted in differences in the timing of recognition of sales commissions. While the adoption of the standard changes certain line items within the net cash flow from operating activities, it had no impact to the net cash provided by or used in operating, investing, or financing activities on our condensed consolidated statements of cash flows. The following line items on our condensed consolidated balance sheet as of January 31, 2018 have been adjusted to reflect the adoption of ASC 606 (in thousands): As of January 31, 2018 As Previously Reported Adjustment As Adjusted Assets Deferred commissions, current $ 22,437 $ (1,349 ) $ 21,088 Deferred commissions, non-current 20,288 45,937 66,225 Total deferred commissions $ 42,725 $ 44,588 $ 87,313 Liabilities Deferred revenue, current $ 209,377 $ (18,148 ) $ 191,229 Deferred revenue, non-current 196,632 (13,759 ) 182,873 Total deferred revenue $ 406,009 $ (31,907 ) $ 374,102 Stockholders' equity Accumulated deficit $ (980,082 ) $ 76,495 $ (903,587 ) The following line items on our unaudited condensed consolidated statement of operations for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASC 606 (in thousands, except per share data): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: Product $ 138,425 $ 4,425 $ 142,850 Support subscription 44,206 (4,411 ) 39,795 Total revenue $ 182,631 $ 14 $ 182,645 Gross profit $ 119,083 $ 14 $ 119,097 Sales and marketing $ 96,964 $ (5,201 ) $ 91,763 Total operating expenses $ 182,488 $ (5,201 ) $ 177,287 Loss from operations $ (63,405 ) $ 5,215 $ (58,190 ) Loss before provision for income taxes $ (61,410 ) $ 5,215 $ (56,195 ) Net loss $ (62,374 ) $ 5,215 $ (57,159 ) Net loss per share attributable to common stockholders, basic and diluted $ (0.30 ) $ 0.02 $ (0.28 ) Unaudited revenue by geographic location based on bill-to location, which reflects the adoption impact of ASC 606, are as follows (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: United States $ 146,494 $ 11 $ 146,505 Rest of the world 36,137 3 36,140 Total revenue $ 182,631 $ 14 $ 182,645 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016-18), which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and restricted cash. We adopted ASU 2016-18 effective February 1, 2018 on a retrospective basis. Upon adoption, restricted cash are included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The adoption of this standard did not impact our net cash flow from operating activities or financing activities presented on our consolidated statements of cash flows. The following line items in our unaudited condensed consolidated statement of cash flows for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASU 2016-18 and ASC 606 (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Net loss (1) $ (62,374 ) $ 5,215 $ (57,159 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Deferred commissions (1) $ (362 ) $ (1,005 ) $ (1,367 ) Accrued compensation and other liabilities (1) $ (19,998 ) $ (4,196 ) $ (24,194 ) Deferred revenue (1) $ 8,398 $ (14 ) $ 8,384 Cash used in operating activities $ (14,301 ) $ — $ (14,301 ) Cash, cash equivalents and restricted cash, beginning of period (2) $ 183,675 $ 12,734 $ 196,409 Cash, cash equivalents and restricted cash, end of period (2) $ 168,757 $ 12,734 $ 181,491 _____________________________________________________ (1) Adjustment pertaining to the adoption of ASC 606. (2) Adjustment pertaining to the adoption of ASU 2016-18. Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize all leases with terms in excess of one year on their balance sheet as a right-of-use asset and a lease liability at the commencement date. The new standard also simplifies the accounting for sale and leaseback transactions. The amendments in this update will be effective for us beginning on February 1, 2019 and must be adopted using a modified retrospective method for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. Early adoption is permitted. We are currently evaluating the impact of this standard on our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 amends guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities to require that credit losses on available-for-sale debt securities be presented as an allowance rather than as a write-down. The measurement of credit losses for newly recognized financial assets and subsequent changes in the allowance for credit losses are recorded in the statements of operations. The amendments in this update will be effective for us beginning on February 1, 2020 with early adoption permitted on or after February 1, 2019. We are currently evaluating the impact of this standard on our consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act and requires certain disclosures about stranded tax effects. This standard will be effective for us beginning February 1, 2019 and should be applied either in the period of adoption or retrospectively. Early adoption is permitted. We do not expect this standard to have any impact on our consolidated financial statements.

Financial Instruments

Financial Instruments	3 Months Ended
	Apr. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Financial Instruments Fair Value Measurements We measure our cash equivalents, marketable securities, and restricted cash at fair value on a recurring basis. We define fair value as the exchange price that would be received from sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We measure our financial assets and liabilities at fair value at each reporting period using a fair value hierarchy which requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value: • Level 1 - Observable inputs are unadjusted quoted prices in active markets for identical assets or liabilities; • Level 2 - Observable inputs are quoted prices for similar assets and liabilities in active markets or inputs other than quoted prices that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments; and • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs are based on our own assumptions used to measure assets and liabilities at fair value and require significant management judgment or estimation. We classify our cash equivalents, marketable securities and restricted cash within Level 1 or Level 2 because they are valued using either quoted market prices or inputs other than quoted prices which are directly or indirectly observable in the market, including readily-available pricing sources for the identical underlying security which may not be actively traded. Our fixed income available-for-sale securities consist of high quality, investment grade securities from diverse issuers. The valuation techniques used to measure the fair value of our marketable securities were derived from non-binding market consensus prices that are corroborated by observable market data or quoted market prices for similar instruments. In addition to our cash equivalents, marketable securities, and restricted cash, we measure the fair value of the Notes on a quarterly basis for disclosure purposes. We consider the fair value of the Notes at April 30, 2018 to be a Level 2 measurement due to limited trading activity of the Notes. Refer to Note 5 for further information. Cash Equivalents, Marketable Securities and Restricted Cash The following tables summarize our cash equivalents, marketable securities and restricted cash by significant investment categories as of January 31, 2018 and April 30, 2018 (in thousands): As of January 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash Equivalents Marketable Securities Restricted Cash Level 1 Money market accounts $ — $ — $ — $ 32,057 $ 17,294 $ — $ 14,763 Level 2 U.S. government treasury notes 131,643 — (651 ) 130,992 10,172 120,820 — U.S. government agencies 47,229 — (333 ) 46,896 — 46,896 — Corporate debt securities 186,506 116 (1,049 ) 185,573 — 185,573 — Total $ 365,378 $ 116 $ (2,033 ) $ 395,518 $ 27,466 $ 353,289 $ 14,763 As of April 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash Equivalents Marketable Securities Restricted Cash Level 1 Money market accounts $ — $ — $ — $ 24,747 $ 8,248 $ — $ 16,499 Level 2 U.S. government treasury notes 146,112 1 (774 ) 145,339 10,419 134,920 — U.S. government agencies 40,674 — (390 ) 40,284 — 40,284 — Corporate debt securities 189,083 76 (1,546 ) 187,613 — 187,613 — Total $ 375,869 $ 77 $ (2,710 ) $ 397,983 $ 18,667 $ 362,817 $ 16,499 The amortized cost and estimated fair value of our marketable securities are shown below by contractual maturity (in thousands): As of April 30, 2018 Amortized Cost Fair Value Due within one year $ 208,672 $ 207,951 Due in one to five years 156,778 154,866 Total $ 365,450 $ 362,817 The gross unrealized losses on our marketable securities as of April 30, 2018 were temporary in nature. The following table presents gross unrealized losses and fair values for those investments that were in a continuous unrealized loss as of April 30, 2018 , aggregated by investment category (in thousands): Less than 12 months Greater than 12 months Total Fair Value Unrealized Loss Fair Unrealized Fair Unrealized U.S. government treasury notes $ 93,195 $ (323 ) $ 40,159 $ (451 ) $ 133,354 $ (774 ) U.S. government agencies 16,216 (190 ) 24,069 (200 ) 40,285 (390 ) Corporate debt securities 119,622 (1,188 ) 33,349 (358 ) 152,971 (1,546 ) Total $ 229,033 $ (1,701 ) $ 97,577 $ (1,009 ) $ 326,610 $ (2,710 ) Realized gains or losses on sale of marketable securities were not significant for all periods presented.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Apr. 30, 2018
Balance Sheet Components Disclosure [Abstract]
Balance Sheet Components	Balance Sheet Components Inventory Inventory consists of the following (in thousands): As of As of Raw materials $ 1,181 $ 124 Finished goods 33,316 38,416 Inventory $ 34,497 $ 38,540 Property and Equipment, Net Property and equipment, net, consists of the following (in thousands): As of As of Test equipment $ 142,311 $ 148,444 Computer equipment and software 72,329 82,102 Furniture and fixtures 5,363 5,611 Leasehold improvements 15,032 18,134 Total property and equipment 235,035 254,291 Less: accumulated depreciation and amortization (145,893 ) (160,011 ) Property and equipment, net $ 89,142 $ 94,280 Depreciation and amortization expense was $14.4 million and $16.0 million for the three months ended April 30, 2017 and 2018 . Intangible Assets, Net Intangible assets, net, consist of the following (in thousands): As of As of Technology patents $ 10,125 $ 10,125 Accumulated amortization (5,068 ) (5,444 ) Intangible assets, net $ 5,057 $ 4,681 Intangible assets amortization expense was $0.4 million for three months ended April 30, 2017 and 2018 . The weighted-average remaining useful life of technology patents is 3.1 years. Due to the defensive nature of these patents, the amortization expense is included in general and administrative expenses in the condensed consolidated statements of operations. As of April 30, 2018 , future expected amortization expense for intangible assets is as follows (in thousands): Years Ending January 31, Estimated Future Amortization Expense Remainder of 2019 $ 1,128 2020 1,504 2021 1,504 2022 545 Total $ 4,681 Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consist of the following (in thousands): As of As of Taxes payable $ 4,052 $ 3,790 Accrued marketing 5,928 4,703 Accrued travel and entertainment expenses 4,386 4,119 Other accrued liabilities 12,463 13,017 Total accrued expenses and other liabilities $ 26,829 $ 25,629

Convertible Senior Notes

Convertible Senior Notes	3 Months Ended
	Apr. 30, 2018
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior Notes In April 2018, we issued $575.0 million in principal amount of 0.125% convertible senior notes (the Notes) due 2023, in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act and received proceeds of $562.1 million , after deducting the underwriters’ discounts and commissions. The Notes are governed by an indenture (the Indenture) between us, as the issuer, and U.S. Bank National Association, as trustee. The Notes are our senior unsecured obligations. The Indenture does not contain any financial covenants or restrictions on the payments of dividends, the incurrence of indebtedness, or the issuance or repurchase of securities by us or any of our subsidiaries. The Notes mature on April 15, 2023 unless repurchased or redeemed by us or converted in accordance with their terms prior to the maturity date. Interest is payable semi-annually in arrears on April 15 and October 15 of each year, beginning on October 15, 2018. The Notes are convertible for up to 21,884,155 shares of our common stock at an initial conversion rate of approximately 38.0594 shares of Class A common stock per $1,000 principal amount, which is equal to an initial conversion price of approximately $26.27 per share of Class A common stock, subject to adjustment. Holders of the Notes may surrender their Notes for conversion at their option at any time prior to the close of business on the business day immediately preceding October 15, 2022, only under the following circumstances: • during any fiscal quarter commencing after the fiscal quarter ending on July 31, 2018 (and only during such fiscal quarter), if the last reported sale price of our Class A common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price for the Notes on each applicable trading day; • during the five business day period after any five consecutive trading day period (the measurement period), in which the trading price per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our Class A common stock and the conversion rate for the Notes on each such trading day; • if we call any or all of the Notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or • upon the occurrence of specified corporate events. On or after October 15, 2022 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their Notes at any time regardless of the foregoing circumstances. Upon conversion, holders will receive cash, shares of our Class A common stock, or a combination of cash and shares of our Class A common stock, at our election. We intend to settle the principal of the Notes in cash. The conversion price will be subject to adjustment in some events. Following certain corporate events that occur prior to the maturity date or following our issuance of a notice of redemption, we will increase the conversion rate for a holder who elects to convert its Notes in connection with such corporate event or during the related redemption period in certain circumstances. Additionally, upon the occurrence of a corporate event that constitutes a “fundamental change” per the Indenture, holders of the Notes may require us to repurchase for cash all or a portion of the Notes at a purchase price equal to 100% of the principal amount of the Notes plus accrued and unpaid contingent interest. We may not redeem the Notes prior to April 20, 2021. We may redeem for cash all or any portion of the Notes, at our option, on or after April 20, 2021 if the last reported sale price of our Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending not more than two trading days immediately preceding the date on which we provide notice of redemption at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the Notes. In accounting for the issuance of the Notes, we separated the Notes into liability and equity components. The carrying amount of the liability component was determined by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was calculated by deducting the fair value of the liability component from the principal amount of the Notes as a whole. The difference between the principal amount of the Notes and the liability component (the debt discount) is amortized to interest expense in the condensed consolidated statements of operations using the effective interest method over the term of the Notes. The equity component of the Notes is included in additional paid-in capital in the condensed consolidated balance sheets and is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the transaction costs related to the issuance of the Notes, we allocated the total amount incurred to the liability and equity components using the same proportions as the initial carrying value of the Notes. Transaction costs attributable to the liability component were netted with the principal amount of the Notes in the condensed consolidated balance sheets and are being amortized to interest expense in the condensed consolidated statements of operations using the effective interest method over the term of the Notes. Transaction costs attributable to the equity component were netted with the equity component of the Notes in additional paid-in capital in the condensed consolidated balance sheets. We recorded total debt issuance costs of $12.9 million , of which approximately $9.8 million was allocated to the Notes and approximately $3.1 million was allocated to additional paid-in capital. The Notes consisted of the following (in thousands): As of Liability: Principal $ 575,000 Less: debt discount, net of amortization (134,976 ) Less: debt issuance costs, net of amortization (9,772 ) Net carrying amount of the Notes $ 430,252 Stockholders' equity: Allocated value of the conversion feature $ 136,333 Less: debt issuance costs (3,068 ) Additional paid-in capital $ 133,265 The total estimated fair value of the Notes as of April 30, 2018 was approximately $595.2 million . The fair value was determined based on the closing trading price per $100 of the Notes as of the last day of trading for the period. The fair value of the Notes is primarily affected by the trading price of our common stock and market interest rates. Based on the closing price of our Class A common stock of $20.23 on April 30, 2018 , the if-converted value of the Notes of $442.7 million was less than its principal amount. The following table sets forth total interest expense recognized related to the Notes for the three months ended April 30, 2018 (in thousands): Three Months Ended April 30, 2018 Amortization of debt discount $ 1,357 Amortization of debt issuance costs 98 Total amortization of debt discount and debt issuance costs 1,455 Contractual interest expense 43 Total interest expense related to the Notes $ 1,498 Effective interest rate of the liability component 5.6 % In connection with the offering of the Notes, we paid $64.6 million to enter into capped call transactions with certain of the underwriters and their affiliates (the Capped Calls), whereby we have the option to purchase a total of 21,884,155 shares of our Class A common stock upon any conversion of Notes and/or offset any cash payments we are required to make in excess of the principal amount of the Notes, as the case may be, with such reduction or offset subject to a cap initially equal to $39.66 per share (which represents a premium of 100% over the last reported sales price of our Class A common stock on April 4, 2018), subject to certain adjustments (the Cap Price). The cost of the Capped Calls was accounted for as a reduction to additional paid-in capital on the condensed consolidated balance sheet. The Capped Calls are intended to reduce or offset potential dilution of our common stock upon any conversion of the Notes, subject to a cap based on the Cap Price. Impact on Earnings Per Share The Notes will not have impact on our diluted earnings per share until the average market price of our Class A common stock exceeds the conversion price of $26.27 per share, as we intend to settle the principal amount of the Notes in cash upon conversion. We are required under the treasury stock method to compute the potentially dilutive shares of common stock related to the Notes for periods we report net income. However, upon conversion, there will be no economic dilution from the Notes until the average market price of our Class A common stock exceeds the Cap Price of $39.66 per share, as exercise of the Capped Calls offsets any dilution from the Notes from the conversion price up to the Cap Price. Capped Calls are excluded from the calculation of diluted earnings per share, as they would be anti-dilutive under the treasury stock method.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Apr. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases As of January 31, 2018 and April 30, 2018 , the aggregate future minimum payments under non-cancelable operating leases were approximately $113.0 million and $154.9 million . Letters of Credit In connection with the lease amendment executed in March 2018, we issued a letter of credit of $1.5 million . As of January 31, 2018 and April 30, 2018 , we had outstanding letters of credit in the aggregate amount of $9.6 million and $11.5 million , in connection with our facility leases. The letters of credit are collateralized by restricted cash and mature on various dates through August 2029 . Legal Matters From time to time, we have become involved in claims and other legal matters arising in the normal course of business. We investigate these claims as they arise. Although claims are inherently unpredictable, we currently are not aware of any matters that we expect to have a material adverse effect on our business, financial position, results of operations or cash flows. Accordingly, we have not recorded any loss contingency on our condensed consolidated balance sheet as of April 30, 2018 . Indemnification Our arrangements generally include certain provisions for indemnifying customers against liabilities if our products or services infringe a third party’s intellectual property rights. Other guarantees or indemnification arrangements include guarantees of product and service performance and standby letters of credit for lease facilities. It is not possible to determine the maximum potential amount under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. To date, we have not incurred any material costs as a result of such obligations and have not accrued any liabilities related to such obligations in the consolidated financial statements. In addition, we indemnify our officers, directors and certain key employees while they are serving in good faith in their respective capacities. To date, there have been no claims under any indemnification provisions.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Apr. 30, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock We have 20,000,000 authorized shares of undesignated preferred stock, the rights, preferences and privileges of which may be designated from time to time by our board of directors. As of April 30, 2018 , there were no shares of preferred stock issued or outstanding. Class A and Class B Common Stock We have two classes of authorized common stock, Class A common stock and Class B common stock. As of April 30, 2018 , we had 2,000,000,000 shares of Class A common stock authorized with a par value of $0.0001 per share and 250,000,000 shares of Class B common stock authorized with a par value of $0.0001 per share. As of April 30, 2018 , 164,207,114 shares of Class A common stock were issued and outstanding and 65,389,256 shares of Class B common stock were issued and outstanding. Repurchase of Common Stock Concurrent with the issuance of the Notes (see Note 5), we repurchased and retired 1,008,573 shares, or $20.0 million , of our Class A common stock at $19.83 per share, which was equal to the closing price per share of our Class A common stock on April 4, 2018, the date of the pricing of the offering of the Notes. The repurchased shares were recorded as a reduction of additional paid-in capital on the condensed consolidated balance sheet.

Equity Incentive Plans

Equity Incentive Plans	3 Months Ended
	Apr. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans	Equity Incentive Plans Equity Incentive Plans We maintain two equity incentive plans: the 2009 Equity Incentive Plan (the 2009 Plan) and the 2015 Equity Incentive Plan (the 2015 Plan). In August 2015, our board of directors adopted, and in September 2015 our stockholders approved, the 2015 Plan, which became effective in connection with our initial public offering (IPO) and serves as the successor to the 2009 Plan. The 2015 Plan provides for grants of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards, and other forms of stock awards to our employees, directors and consultants. We initially reserved 27,000,000 shares of our Class A common stock for issuance under our 2015 Plan. The number of shares reserved for issuance under our 2015 Plan increases automatically on the first day of February of each year through 2025, in an amount equal to 5% of the total number of shares of our capital stock outstanding as of the immediately preceding January 31. The exercise price of stock options will generally not be less than 100% of the fair market value of our common stock on the date of grant, as determined by our board of directors. Our equity awards generally vest over a two to four year period and expire no later than ten years from the date of grant. 2015 Employee Stock Purchase Plan In August 2015, our board of directors adopted and our stockholders approved, the 2015 Employee Stock Purchase Plan (2015 ESPP), which became effective in connection with our IPO. A total of 3,500,000 shares of Class A common stock was initially reserved for issuance under the 2015 ESPP. The number of shares reserved for issuance under our 2015 ESPP increases automatically on the first day of February of each year through 2025, in an amount equal to the lesser of (i) 1% of the total number of shares of our capital stock outstanding as of the immediately preceding January 31, and (ii) 3,500,000 shares of Class A common stock. The 2015 ESPP allows eligible employees to purchase shares of our Class A common stock at a discount through payroll deductions of up to 30% of their eligible compensation, subject to a cap of 3,000 shares on any purchase date or $25,000 in any calendar year (as determined under applicable tax rules). The 2015 ESPP provides for 24 month offering periods beginning March 16th and September 16th of each year, and each offering period consists of four six -month purchase periods, subject to a reset provision. If the closing stock price on the offering date of a new offering falls below the closing stock price on the offering date of an ongoing offering, the ongoing offering would terminate immediately following the purchase of ESPP shares on the purchase date immediately preceding the new offering and participants in the terminated ongoing offering would automatically be enrolled in the new offering (ESPP reset), resulting in a modification. On each purchase date, eligible employees will purchase our Class A common stock at a price per share equal to 85% of the lesser of the fair market value of our Class A common stock on (1) the first trading day of the applicable offering period or (2) the purchase date. There was an ESPP reset in the three months ended April 30, 2017 that resulted in a total modification charge of $9.0 million , which is recognized over the new offering period ending March 15, 2019. We recognized stock-based compensation expense related to our 2015 ESPP of $4.1 million and $6.7 million during the three months ended April 30, 2017 and 2018 . As of April 30, 2018 , there was $32.6 million of unrecognized stock-based compensation expense related to our 2015 ESPP which is expected to be recognized over a weighted-average period of approximately 1.1 years. Stock Options A summary of stock option activity under our equity incentive plans and related information is as follows: Options Outstanding Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (In Years) Aggregate Intrinsic Value (in thousands) Balance as of January 31, 2018 46,359,949 $ 7.75 6.3 $ 574,224 Options exercised (2,193,658 ) 4.40 Options forfeited/canceled (1,019,718 ) 8.25 Balance as of April 30, 2018 43,146,573 $ 7.91 6.1 $ 531,452 Vested and exercisable as of April 30, 2018 28,635,271 $ 5.66 5.6 $ 417,279 The aggregate intrinsic value of options vested and exercisable as of April 30, 2018 is calculated based on the difference between the exercise price and the closing price of $20.23 of our Class A common stock on April 30, 2018 . As of April 30, 2018 , total unrecognized employee compensation cost related to outstanding options was $60.4 million , which is expected to be recognized over a weighted-average period of approximately 2.2 years. Restricted Stock Units A summary of the restricted stock unit activity under our 2015 Plan and related information is as follows: Number of Restricted Stock Units Outstanding Weighted- Average Grant Date Fair Value Aggregate Unvested balance as of January 31, 2018 17,682,646 $ 12.60 $ 356,117 Granted 6,364,772 20.06 Vested (2,013,408 ) 11.70 Forfeited (437,921 ) 13.68 Converted (1,142,838 ) 11.86 Unvested balance as of April 30, 2018 20,453,251 $ 15.01 $ 413,588 As of April 30, 2018 , total unrecognized employee compensation cost related to unvested restricted stock units was $275.7 million , which is expected to be recognized over a weighted-average period of approximately 3.1 years. In March 2017, we granted 750,000 performance stock units (net of 77,000 canceled units), at a target percentage of 100%, with both performance and service vesting conditions payable in common shares, from 0% to 150% of the target number granted, contingent upon the degree to which the performance condition is met. In the three months ended April 30, 2018 , a total of 780,000 shares was earned based on the performance condition achieved and these shares will be subject to service conditions through the vesting periods. Stock-based compensation expense for these performance stock units was $0.5 million and $0.7 million for the three months ended April 30, 2017 and 2018 , recognized on an accelerated attribution method. In August 2017, we granted 464,744 performance stock units, at a target percentage of 100% , with both performance and service vesting conditions payable in common shares, from 0% to 150% of the target number granted, contingent upon the degree to which the performance condition is met. The performance condition for these performance stock units was set in March 2018 and accordingly, established the grant date for these awards from an accounting perspective and for determining the grant date fair value. Restricted Stock During the three months ended April 30, 2018 , we converted certain restricted stock units and performance stock units that were previously granted into 1,375,210 shares of restricted stock for corporate tax benefit purposes. Of the 1,375,210 shares of restricted stock, 697,116 shares are performance restricted stock and 678,094 shares are subject to service vesting conditions only. The conversion did not change the fair value or vesting conditions and therefore no modification accounting is required. During the three months ended April 30, 2018 , we issued 1,933,861 shares of performance restricted stock, at the maximum performance percentage of 180% , with performance vesting conditions payable in common shares, contingent upon the degree to which the performance condition is met. The shares may be earned from 0% to 180% . Actual shares earned may be lower than the aggregate maximum number dependent on the degree to which the performance condition is met, and cannot be higher than the aggregate maximum number. Any portion of shares that are not earned will be canceled. All unvested restricted shares are subject to repurchase. Stock-based compensation expense for performance restricted stock is recognized on an accelerated attribution method. In the three months ended April 30, 2018 , we recognized $3.5 million in stock-based compensation expense relating to restricted stock. As of April 30, 2018 , total unrecognized employee compensation cost related to unvested restricted stock was $36.9 million , which is expected to be recognized over a weighted-average period of approximately 2.9 years. Stock-Based Compensation Expense The following table summarizes the components of stock-based compensation expense recognized in the condensed consolidated statements of operations (in thousands): Three Months Ended 2017 2018 Cost of revenue—product $ 397 $ 608 Cost of revenue—support subscription 1,774 2,684 Research and development 15,588 21,090 Sales and marketing 10,626 13,940 General and administrative 3,834 5,633 Total stock-based compensation expense $ 32,219 $ 43,955 The tax benefit related to stock-based compensation expense for all periods presented was not material.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	3 Months Ended
	Apr. 30, 2018
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for participating securities. Basic net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase. Diluted net loss per share attributable to common stockholders is computed by giving effect to all potentially dilutive common stock equivalents including our outstanding stock options, common stock related to unvested early exercised stock options, common stock related to unvested restricted stock units and restricted stock awards, convertible senior notes to the extent dilutive, and common stock issuable pursuant to the ESPP. For purposes of calculating basic and diluted net loss per share attributable to common shareholders, these potentially dilutive common stock equivalents have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is anti-dilutive. The rights, including the liquidation and dividend rights, of the holders of our Class A and Class B common stock are identical, except with respect to voting. As the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis and the resulting net loss per share attributed to common stockholders will, therefore, be the same for both Class A and Class B common stock on an individual or combined basis. The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data): Three Months Ended 2017 2018 (As Adjusted*) Net loss $ (57,159 ) $ (64,304 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 205,783 223,768 Net loss per share attributable to common stockholders, basic and diluted $ (0.28 ) $ (0.29 ) * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018. The following weighted-average outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands): Three Months Ended 2017 2018 Stock options to purchase common stock 55,895 44,996 Restricted stock units 11,722 18,999 Restricted stock and early exercised stock options 390 1,685 Employee stock purchase plan 336 470 Total 68,343 66,150

Income Taxes

Income Taxes	3 Months Ended
	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our provision for income taxes was primarily due to taxes on international operations and state income taxes. The difference between the provision for income taxes that would be derived by applying the statutory rate to our loss before income taxes and the provision for income taxes recorded was primarily attributable to changes in our valuation allowance, non-deductible stock-based compensation expense and the tax rate differential between the U.S. and foreign countries. As of April 30, 2018 , there were no material changes to either the nature or the amounts of the uncertain tax positions previously determined for the year ended January 31, 2018 . The Tax Cuts and Jobs Act (the Tax Act) was signed into law on December 22, 2017. The new legislation decreases the U.S. corporate federal income tax rate from 35% to 21% effective January 1, 2018. The Tax Act also includes a number of other provisions including the elimination of loss carrybacks and limitations on the use of future losses, limitations on the deductibility of executive compensation, limitation or modification on the deductibility of certain business expenses, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and the introduction of a base erosion and anti-abuse tax. Under the Tax Act, the Global Intangible Low-Taxed Income (GILTI) provision taxes foreign income in excess of a deemed return on tangible assets of foreign corporations. Under U.S. GAAP, companies are allowed to make an accounting policy election to either (i) account for GILTI as a component of tax expense in the period in which a company is subject to the rules -- the period cost method, or (ii) account for GILTI in a company’s measurement of deferred taxes -- the deferred method. Because of the complexity of the new tax rules, we have not yet made an accounting policy election and are continuing to assess the impact of the Tax Act during the one-year measurement period from the Tax Act enactment date as allowed by Staff Accounting Bulletin No. 118 (SAB 118) issued in connection with the Tax Act. We expect to complete the accounting for the tax effects of the Tax Act in calendar year 2018.

Segment Information

Segment Information	3 Months Ended
	Apr. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information Our chief operating decision maker is a group comprised of our Chief Executive Officer, our Chief Financial Officer, and our President. This group reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. We have one business activity and there are no segment managers who are held accountable for operations or operating results. Accordingly, we have a single reportable segment. Disaggregation of Revenue The following table depicts the disaggregation of revenue by geographic area based on the billing address of our customers and is consistent with how we evaluate our financial performance (in thousands): Three Months Ended 2017 2018 (As Adjusted*) United States $ 146,505 $ 184,918 Rest of the world 36,140 71,027 Total revenue $ 182,645 $ 255,945 * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018. Long-Lived Assets by Geographic Area Long-lived assets by geographic area are summarized as follows (in thousands): As of As of United States $ 85,430 $ 90,203 Rest of the world 3,712 4,077 Total long-lived assets $ 89,142 $ 94,280

Basis of Presentation and Sum18

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Apr. 30, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of the company and our wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Unaudited Interim Consolidated Financial Information	Unaudited Interim Consolidated Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) and applicable rules and regulations of the Securities and Exchange Commission (the SEC) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended January 31, 2018 . In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year 2019 or any future period. Certain prior period amounts have been adjusted as a result of adoption of new accounting pronouncements. Refer to " Recently Adopted Accounting Pronouncements" below for further information.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the financial statements and accompanying notes. Actual results could differ from these estimates. Such estimates include, but are not limited to, the determination of standalone selling price for revenue arrangements with multiple performance obligations, useful lives of intangible assets, property and equipment and deferred sales commissions, fair values of stock-based awards, provision for income taxes including related reserves, and contingent liabilities, among others. Management bases its estimates on historical experience and on various other assumptions which management believes to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities.
Restricted Cash	Restricted Cash Restricted cash is comprised of cash collateral related to our leases and for a vendor corporate credit card program.
Marketable Securities	Marketable Securities We classify our marketable securities as available-for-sale at the time of purchase and reevaluate such classification at each balance sheet date. We may sell these securities at any time for use in current operations even if they have not yet reached maturity. As a result, we classify our securities, including those with maturities beyond twelve months, as current assets in the accompanying condensed consolidated balance sheets. We carry these securities at fair value and record unrealized gains and losses, in other comprehensive income (loss), which is reflected as a component of stockholders’ equity. We evaluate our securities to assess whether those with unrealized loss positions are other than temporarily impaired. We consider impairments to be other than temporary if they are related to deterioration in credit risk or if it is likely we will sell the securities before the recovery of their cost basis. Realized gains and losses from the sale of marketable securities and declines in value deemed to be other than temporary are determined on the specific identification method. To date, there have been no declines in value deemed to be other than temporary in any of our securities. Realized gains and losses are reported in other income (expense), net in the condensed consolidated statements of operations.
Deferred Commissions	Deferred Commissions Deferred commissions consist of incremental costs paid to our sales force to obtain customer contracts. Deferred commissions related to product revenues are recognized upon transfer of control to customers and deferred commissions related to support subscription revenue are amortized over an expected useful life of six years. We determine the expected useful life based on an estimated benefit period by evaluating our technology development life cycle, expected customer relationship period, and other factors. We classify deferred commissions as current and non-current on our condensed consolidated balance sheets based on the timing of when we expect to recognize the expense. Amortization of deferred commissions is included in sales and marketing expense in the condensed consolidated statements of operations.
Deferred Revenue	Deferred Revenue Deferred revenue primarily consists of amounts that have been invoiced but that have not yet been recognized as revenue and consists of performance obligations pertaining to support subscription services. The current portion of deferred revenue represents the amounts that are expected to be recognized as revenue within one year of the condensed consolidated balance sheet dates.
Revenue Recognition	Revenue Recognition We derive revenue from two sources: (1) product revenue which includes hardware and embedded software and (2) support subscription revenue which includes customer support, hardware maintenance, and software upgrades on a when-and-if-available basis. Our product revenue is derived from the sale of storage hardware and operating system software that is integrated into the hardware. We typically recognize product revenue upon transfer of control to our customers. Products are typically shipped directly by us to customers, and our channel partners do not stock our inventory. Our support subscription revenue is derived from the sale of support subscription, which includes the right to receive unspecified software upgrades and enhancements on a when-and-if-available basis, bug fixes, parts replacement services related to the hardware, as well as access to our cloud-based management and support platform. Revenue related to support subscription is recognized ratably over the contractual term, which generally ranges from one to six years and represents our performance obligations period. The vast majority of our products are sold with support subscription agreements, which typically commence upon transfer of control of the corresponding products to our customers. Costs to service the support subscription are expensed as incurred. In addition, our Evergreen Storage program provides our customers who continually maintain active support subscription agreements for three years with an included controller refresh with each additional three year support subscription renewal. In accordance with revenue recognition guidance, the controller refresh represents an additional performance obligation and the allocated revenue is recognized in the period in which these controllers are shipped. We recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration we expect to be entitled in exchange for those goods or services. This is achieved through applying the following five-step approach: • Identification of the contract, or contracts, with a customer • Identification of the performance obligations in the contract • Determination of the transaction price • Allocation of the transaction price to the performance obligations in the contract • Recognition of revenue when, or as, we satisfy a performance obligation When applying this five-step approach, we apply judgment in determining the customer's ability and intention to pay, which is based on a variety of factors including the customer's historical payment experience and/or published credit and financial information pertaining to the customer. To the extent a customer contract includes multiple promised goods or services, we determine whether promised goods or services are capable of being distinct in the context of the contract to be accounted for as a combined performance obligation. We allocate transaction price to each performance obligation for contracts that contain multiple performance obligations based on a relative standalone selling price, taking into account available information such as market conditions and internally approved pricing guidelines related to performance obligations.
Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB), issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09 or ASC 606), requiring an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASC 606 supersedes nearly all existing revenue recognition guidance under U.S. GAAP upon its effective date. The standard permits two methods of adoptions: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of applying the standard recognized at the date of application (cumulative catch-up transition method). We adopted the standard using the full retrospective method beginning February 1, 2018, for the year ending January 31, 2019, and our historical financial information for the years ended January 31, 2017 and 2018 has been adjusted to conform to the new standard. The most significant impact of the standard related to the removal of limitation on contingent revenue, resulting in an increase in product revenue and a decrease in support subscription revenue. In addition, the adoption of ASC 606 also resulted in differences in the timing of recognition of sales commissions. While the adoption of the standard changes certain line items within the net cash flow from operating activities, it had no impact to the net cash provided by or used in operating, investing, or financing activities on our condensed consolidated statements of cash flows. The following line items on our condensed consolidated balance sheet as of January 31, 2018 have been adjusted to reflect the adoption of ASC 606 (in thousands): As of January 31, 2018 As Previously Reported Adjustment As Adjusted Assets Deferred commissions, current $ 22,437 $ (1,349 ) $ 21,088 Deferred commissions, non-current 20,288 45,937 66,225 Total deferred commissions $ 42,725 $ 44,588 $ 87,313 Liabilities Deferred revenue, current $ 209,377 $ (18,148 ) $ 191,229 Deferred revenue, non-current 196,632 (13,759 ) 182,873 Total deferred revenue $ 406,009 $ (31,907 ) $ 374,102 Stockholders' equity Accumulated deficit $ (980,082 ) $ 76,495 $ (903,587 ) The following line items on our unaudited condensed consolidated statement of operations for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASC 606 (in thousands, except per share data): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: Product $ 138,425 $ 4,425 $ 142,850 Support subscription 44,206 (4,411 ) 39,795 Total revenue $ 182,631 $ 14 $ 182,645 Gross profit $ 119,083 $ 14 $ 119,097 Sales and marketing $ 96,964 $ (5,201 ) $ 91,763 Total operating expenses $ 182,488 $ (5,201 ) $ 177,287 Loss from operations $ (63,405 ) $ 5,215 $ (58,190 ) Loss before provision for income taxes $ (61,410 ) $ 5,215 $ (56,195 ) Net loss $ (62,374 ) $ 5,215 $ (57,159 ) Net loss per share attributable to common stockholders, basic and diluted $ (0.30 ) $ 0.02 $ (0.28 ) Unaudited revenue by geographic location based on bill-to location, which reflects the adoption impact of ASC 606, are as follows (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: United States $ 146,494 $ 11 $ 146,505 Rest of the world 36,137 3 36,140 Total revenue $ 182,631 $ 14 $ 182,645 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016-18), which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and restricted cash. We adopted ASU 2016-18 effective February 1, 2018 on a retrospective basis. Upon adoption, restricted cash are included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The adoption of this standard did not impact our net cash flow from operating activities or financing activities presented on our consolidated statements of cash flows. The following line items in our unaudited condensed consolidated statement of cash flows for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASU 2016-18 and ASC 606 (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Net loss (1) $ (62,374 ) $ 5,215 $ (57,159 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Deferred commissions (1) $ (362 ) $ (1,005 ) $ (1,367 ) Accrued compensation and other liabilities (1) $ (19,998 ) $ (4,196 ) $ (24,194 ) Deferred revenue (1) $ 8,398 $ (14 ) $ 8,384 Cash used in operating activities $ (14,301 ) $ — $ (14,301 ) Cash, cash equivalents and restricted cash, beginning of period (2) $ 183,675 $ 12,734 $ 196,409 Cash, cash equivalents and restricted cash, end of period (2) $ 168,757 $ 12,734 $ 181,491 _____________________________________________________ (1) Adjustment pertaining to the adoption of ASC 606. (2) Adjustment pertaining to the adoption of ASU 2016-18. Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize all leases with terms in excess of one year on their balance sheet as a right-of-use asset and a lease liability at the commencement date. The new standard also simplifies the accounting for sale and leaseback transactions. The amendments in this update will be effective for us beginning on February 1, 2019 and must be adopted using a modified retrospective method for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. Early adoption is permitted. We are currently evaluating the impact of this standard on our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 amends guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities to require that credit losses on available-for-sale debt securities be presented as an allowance rather than as a write-down. The measurement of credit losses for newly recognized financial assets and subsequent changes in the allowance for credit losses are recorded in the statements of operations. The amendments in this update will be effective for us beginning on February 1, 2020 with early adoption permitted on or after February 1, 2019. We are currently evaluating the impact of this standard on our consolidated financial statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act and requires certain disclosures about stranded tax effects. This standard will be effective for us beginning February 1, 2019 and should be applied either in the period of adoption or retrospectively. Early adoption is permitted. We do not expect this standard to have any impact on our consolidated financial statements.
Fair Value Measurements	Fair Value Measurements We measure our cash equivalents, marketable securities, and restricted cash at fair value on a recurring basis. We define fair value as the exchange price that would be received from sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We measure our financial assets and liabilities at fair value at each reporting period using a fair value hierarchy which requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value: • Level 1 - Observable inputs are unadjusted quoted prices in active markets for identical assets or liabilities; • Level 2 - Observable inputs are quoted prices for similar assets and liabilities in active markets or inputs other than quoted prices that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments; and • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs are based on our own assumptions used to measure assets and liabilities at fair value and require significant management judgment or estimation. We classify our cash equivalents, marketable securities and restricted cash within Level 1 or Level 2 because they are valued using either quoted market prices or inputs other than quoted prices which are directly or indirectly observable in the market, including readily-available pricing sources for the identical underlying security which may not be actively traded. Our fixed income available-for-sale securities consist of high quality, investment grade securities from diverse issuers. The valuation techniques used to measure the fair value of our marketable securities were derived from non-binding market consensus prices that are corroborated by observable market data or quoted market prices for similar instruments. In addition to our cash equivalents, marketable securities, and restricted cash, we measure the fair value of the Notes on a quarterly basis for disclosure purposes. We consider the fair value of the Notes at April 30, 2018 to be a Level 2 measurement due to limited trading activity of the Notes. Refer to Note 5 for further information.

Basis of Presentation and Sum19

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Apr. 30, 2018
Accounting Policies [Abstract]
Deferred Commissions and Deferred Revenue	Changes in total deferred revenue during the three months ended April 30, 2018 are as follows (in thousands): Three Months Ended Beginning balance as of January 31, 2018 (as adjusted) $ 374,102 Additions 75,271 Recognition of deferred revenue (60,759 ) Ending balance as of April 30, 2018 $ 388,614 Changes in total deferred commissions during the period presented are as follows (in thousands): Three Months Ended Beginning balance as of January 31, 2018 (as adjusted) $ 87,313 Additions 15,421 Recognition of deferred commissions (16,690 ) Ending balance as of April 30, 2018 $ 86,044
Schedule of Recently Adopted Accounting Pronouncements	The following line items in our unaudited condensed consolidated statement of cash flows for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASU 2016-18 and ASC 606 (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Net loss (1) $ (62,374 ) $ 5,215 $ (57,159 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Deferred commissions (1) $ (362 ) $ (1,005 ) $ (1,367 ) Accrued compensation and other liabilities (1) $ (19,998 ) $ (4,196 ) $ (24,194 ) Deferred revenue (1) $ 8,398 $ (14 ) $ 8,384 Cash used in operating activities $ (14,301 ) $ — $ (14,301 ) Cash, cash equivalents and restricted cash, beginning of period (2) $ 183,675 $ 12,734 $ 196,409 Cash, cash equivalents and restricted cash, end of period (2) $ 168,757 $ 12,734 $ 181,491 _____________________________________________________ (1) Adjustment pertaining to the adoption of ASC 606. (2) Adjustment pertaining to the adoption of ASU 2016-18. The following line items on our condensed consolidated balance sheet as of January 31, 2018 have been adjusted to reflect the adoption of ASC 606 (in thousands): As of January 31, 2018 As Previously Reported Adjustment As Adjusted Assets Deferred commissions, current $ 22,437 $ (1,349 ) $ 21,088 Deferred commissions, non-current 20,288 45,937 66,225 Total deferred commissions $ 42,725 $ 44,588 $ 87,313 Liabilities Deferred revenue, current $ 209,377 $ (18,148 ) $ 191,229 Deferred revenue, non-current 196,632 (13,759 ) 182,873 Total deferred revenue $ 406,009 $ (31,907 ) $ 374,102 Stockholders' equity Accumulated deficit $ (980,082 ) $ 76,495 $ (903,587 ) The following line items on our unaudited condensed consolidated statement of operations for the three months ended April 30, 2017 have been adjusted to reflect the adoption of ASC 606 (in thousands, except per share data): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: Product $ 138,425 $ 4,425 $ 142,850 Support subscription 44,206 (4,411 ) 39,795 Total revenue $ 182,631 $ 14 $ 182,645 Gross profit $ 119,083 $ 14 $ 119,097 Sales and marketing $ 96,964 $ (5,201 ) $ 91,763 Total operating expenses $ 182,488 $ (5,201 ) $ 177,287 Loss from operations $ (63,405 ) $ 5,215 $ (58,190 ) Loss before provision for income taxes $ (61,410 ) $ 5,215 $ (56,195 ) Net loss $ (62,374 ) $ 5,215 $ (57,159 ) Net loss per share attributable to common stockholders, basic and diluted $ (0.30 ) $ 0.02 $ (0.28 ) Unaudited revenue by geographic location based on bill-to location, which reflects the adoption impact of ASC 606, are as follows (in thousands): Three Months Ended As Previously Reported Adjustment As Adjusted Revenue: United States $ 146,494 $ 11 $ 146,505 Rest of the world 36,137 3 36,140 Total revenue $ 182,631 $ 14 $ 182,645

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Apr. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Cash Equivalents, Marketable Securities and Restricted Cash by Significant Investment Categories	The following tables summarize our cash equivalents, marketable securities and restricted cash by significant investment categories as of January 31, 2018 and April 30, 2018 (in thousands): As of January 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash Equivalents Marketable Securities Restricted Cash Level 1 Money market accounts $ — $ — $ — $ 32,057 $ 17,294 $ — $ 14,763 Level 2 U.S. government treasury notes 131,643 — (651 ) 130,992 10,172 120,820 — U.S. government agencies 47,229 — (333 ) 46,896 — 46,896 — Corporate debt securities 186,506 116 (1,049 ) 185,573 — 185,573 — Total $ 365,378 $ 116 $ (2,033 ) $ 395,518 $ 27,466 $ 353,289 $ 14,763 As of April 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash Equivalents Marketable Securities Restricted Cash Level 1 Money market accounts $ — $ — $ — $ 24,747 $ 8,248 $ — $ 16,499 Level 2 U.S. government treasury notes 146,112 1 (774 ) 145,339 10,419 134,920 — U.S. government agencies 40,674 — (390 ) 40,284 — 40,284 — Corporate debt securities 189,083 76 (1,546 ) 187,613 — 187,613 — Total $ 375,869 $ 77 $ (2,710 ) $ 397,983 $ 18,667 $ 362,817 $ 16,499
Schedule of Amortized Cost and Estimated Fair Value of Marketable Securities by Contractual Maturity	The amortized cost and estimated fair value of our marketable securities are shown below by contractual maturity (in thousands): As of April 30, 2018 Amortized Cost Fair Value Due within one year $ 208,672 $ 207,951 Due in one to five years 156,778 154,866 Total $ 365,450 $ 362,817
Schedule of Gross Unrealized Losses and Fair Values for Investments that were in Continuous Unrealized Loss Position for Less Than 12 Months, Aggregated by Investments Category	The following table presents gross unrealized losses and fair values for those investments that were in a continuous unrealized loss as of April 30, 2018 , aggregated by investment category (in thousands): Less than 12 months Greater than 12 months Total Fair Value Unrealized Loss Fair Unrealized Fair Unrealized U.S. government treasury notes $ 93,195 $ (323 ) $ 40,159 $ (451 ) $ 133,354 $ (774 ) U.S. government agencies 16,216 (190 ) 24,069 (200 ) 40,285 (390 ) Corporate debt securities 119,622 (1,188 ) 33,349 (358 ) 152,971 (1,546 ) Total $ 229,033 $ (1,701 ) $ 97,577 $ (1,009 ) $ 326,610 $ (2,710 )

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Apr. 30, 2018
Balance Sheet Components Disclosure [Abstract]
Schedule of Inventory	Inventory consists of the following (in thousands): As of As of Raw materials $ 1,181 $ 124 Finished goods 33,316 38,416 Inventory $ 34,497 $ 38,540
Schedule of Property and Equipment, Net	Property and equipment, net, consists of the following (in thousands): As of As of Test equipment $ 142,311 $ 148,444 Computer equipment and software 72,329 82,102 Furniture and fixtures 5,363 5,611 Leasehold improvements 15,032 18,134 Total property and equipment 235,035 254,291 Less: accumulated depreciation and amortization (145,893 ) (160,011 ) Property and equipment, net $ 89,142 $ 94,280
Schedule of Intangible Assets, Net	Intangible assets, net, consist of the following (in thousands): As of As of Technology patents $ 10,125 $ 10,125 Accumulated amortization (5,068 ) (5,444 ) Intangible assets, net $ 5,057 $ 4,681
Schedule of Expected Amortization Expenses for Intangible Assets	As of April 30, 2018 , future expected amortization expense for intangible assets is as follows (in thousands): Years Ending January 31, Estimated Future Amortization Expense Remainder of 2019 $ 1,128 2020 1,504 2021 1,504 2022 545 Total $ 4,681
Schedule of Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consist of the following (in thousands): As of As of Taxes payable $ 4,052 $ 3,790 Accrued marketing 5,928 4,703 Accrued travel and entertainment expenses 4,386 4,119 Other accrued liabilities 12,463 13,017 Total accrued expenses and other liabilities $ 26,829 $ 25,629

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	3 Months Ended
	Apr. 30, 2018
Debt Disclosure [Abstract]
Convertible Debt	The Notes consisted of the following (in thousands): As of Liability: Principal $ 575,000 Less: debt discount, net of amortization (134,976 ) Less: debt issuance costs, net of amortization (9,772 ) Net carrying amount of the Notes $ 430,252 Stockholders' equity: Allocated value of the conversion feature $ 136,333 Less: debt issuance costs (3,068 ) Additional paid-in capital $ 133,265
Interest Expense	The following table sets forth total interest expense recognized related to the Notes for the three months ended April 30, 2018 (in thousands): Three Months Ended April 30, 2018 Amortization of debt discount $ 1,357 Amortization of debt issuance costs 98 Total amortization of debt discount and debt issuance costs 1,455 Contractual interest expense 43 Total interest expense related to the Notes $ 1,498 Effective interest rate of the liability component 5.6 %

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	3 Months Ended
	Apr. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity Under Equity Incentive Plans and Related Information	A summary of stock option activity under our equity incentive plans and related information is as follows: Options Outstanding Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (In Years) Aggregate Intrinsic Value (in thousands) Balance as of January 31, 2018 46,359,949 $ 7.75 6.3 $ 574,224 Options exercised (2,193,658 ) 4.40 Options forfeited/canceled (1,019,718 ) 8.25 Balance as of April 30, 2018 43,146,573 $ 7.91 6.1 $ 531,452 Vested and exercisable as of April 30, 2018 28,635,271 $ 5.66 5.6 $ 417,279
Summary of Restricted Stock Unit Activity Under 2015 Plan	A summary of the restricted stock unit activity under our 2015 Plan and related information is as follows: Number of Restricted Stock Units Outstanding Weighted- Average Grant Date Fair Value Aggregate Unvested balance as of January 31, 2018 17,682,646 $ 12.60 $ 356,117 Granted 6,364,772 20.06 Vested (2,013,408 ) 11.70 Forfeited (437,921 ) 13.68 Converted (1,142,838 ) 11.86 Unvested balance as of April 30, 2018 20,453,251 $ 15.01 $ 413,588
Summarizes the Components of Stock-Based Compensation	The following table summarizes the components of stock-based compensation expense recognized in the condensed consolidated statements of operations (in thousands): Three Months Ended 2017 2018 Cost of revenue—product $ 397 $ 608 Cost of revenue—support subscription 1,774 2,684 Research and development 15,588 21,090 Sales and marketing 10,626 13,940 General and administrative 3,834 5,633 Total stock-based compensation expense $ 32,219 $ 43,955

Net Loss per Share Attributab24

Net Loss per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Apr. 30, 2018
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except per share data): Three Months Ended 2017 2018 (As Adjusted*) Net loss $ (57,159 ) $ (64,304 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 205,783 223,768 Net loss per share attributable to common stockholders, basic and diluted $ (0.28 ) $ (0.29 ) * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
Summary of Weighted-average Outstanding Shares Excluded from Computation of Diluted Net Loss per Share Attributable to Common Stockholders	The following weighted-average outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands): Three Months Ended 2017 2018 Stock options to purchase common stock 55,895 44,996 Restricted stock units 11,722 18,999 Restricted stock and early exercised stock options 390 1,685 Employee stock purchase plan 336 470 Total 68,343 66,150

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Apr. 30, 2018
Segment Reporting [Abstract]
Schedule of Revenue by Geographic Area	The following table depicts the disaggregation of revenue by geographic area based on the billing address of our customers and is consistent with how we evaluate our financial performance (in thousands): Three Months Ended 2017 2018 (As Adjusted*) United States $ 146,505 $ 184,918 Rest of the world 36,140 71,027 Total revenue $ 182,645 $ 255,945 * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
Schedule of Long-Lived Assets by Geographic Area	Long-lived assets by geographic area are summarized as follows (in thousands): As of As of United States $ 85,430 $ 90,203 Rest of the world 3,712 4,077 Total long-lived assets $ 89,142 $ 94,280

Basis of Presentation and Sum26

Basis of Presentation and Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Accounting Policies [Abstract]
Restricted cash	$ 16,499	$ 14,763

Basis of Presentation and Sum27

Basis of Presentation and Summary of Significant Accounting Policies - Deferred Commissions (Details)	3 Months Ended
	Apr. 30, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	3 years 1 month 6 days
Contract Assets
Beginning balance as of January 31, 2018 (as adjusted)	$ 87,313,000
Additions	15,421,000
Recognition of deferred commissions	16,690,000
Ending balance as of April 30, 2018	86,044,000
Impairment loss, capitalized commissions	$ 0
Servicing Contracts
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	6 years

Basis of Presentation and Sum28

Basis of Presentation and Summary of Significant Accounting Policies - Deferred Commissions (Typed Dimensions) (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-05-01	3 Months Ended
	Apr. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage	23.00%
Remaining performance obligation, expected timing	1 year

Basis of Presentation and Sum29

Basis of Presentation and Summary of Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Contract Liability
Beginning balance as of January 31, 2018 (as adjusted)	$ 374,102
Additions	75,271
Recognition of deferred revenue	60,759
Ending balance as of April 30, 2018	388,614
Product Revenue and Support Subscription Revenue
Contract Liability
Recognition of deferred revenue	$ (55,600)	$ (43,000)

Basis of Presentation and Sum30

Basis of Presentation and Summary of Significant Accounting Policies - Deferred Revenue (Typed Dimensions) (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-05-01	3 Months Ended
	Apr. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage	51.00%
Remaining performance obligation, expected timing	1 year

Basis of Presentation and Sum31

Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Balance Sheet) (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Assets
Deferred commissions, current	$ 20,122	$ 21,088	[1]
Deferred commissions, non-current	65,922	66,225	[1]
Total deferred commissions		87,313
Liabilities
Deferred revenue, current	199,622	191,229	[1]
Deferred revenue, non-current	188,992	182,873	[1]
Total deferred revenue		374,102
Stockholders' equity
Accumulated deficit	$ (967,891)	(903,587)	[1]
As Previously Reported
Assets
Deferred commissions, current		22,437
Deferred commissions, non-current		20,288
Total deferred commissions		42,725
Liabilities
Deferred revenue, current		209,377
Deferred revenue, non-current		196,632
Total deferred revenue		406,009
Stockholders' equity
Accumulated deficit		(980,082)
Adjustment | Accounting Standards Update 2014-09
Assets
Deferred commissions, current		(1,349)
Deferred commissions, non-current		45,937
Total deferred commissions		44,588
Liabilities
Deferred revenue, current		(18,148)
Deferred revenue, non-current		(13,759)
Total deferred revenue		(31,907)
Stockholders' equity
Accumulated deficit		$ 76,495
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Basis of Presentation and Sum32

Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Statement of Operations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Revenue:
Product	$ 195,449	$ 142,850	[1]
Support subscription	60,496	39,795	[1]
Total revenue	255,945	182,645	[1]
Gross profit	166,315	119,097	[1]
Sales and marketing	122,367	91,763	[1]
Total operating expenses	228,189	177,287	[1]
Loss from operations	(61,874)	(58,190)	[1]
Loss before provision for income taxes	(62,873)	(56,195)	[1]
Net loss	$ (64,304)	$ (57,159)	[1],[2],[3]
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.29)	$ (0.28)	[1]
As Previously Reported
Revenue:
Product		$ 138,425
Support subscription		44,206
Total revenue		182,631
Gross profit		119,083
Sales and marketing		96,964
Total operating expenses		182,488
Loss from operations		(63,405)
Loss before provision for income taxes		(61,410)
Net loss		$ (62,374)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)		$ (0.30)
Adjustment | Accounting Standards Update 2014-09
Revenue:
Product		$ 4,425
Support subscription		(4,411)
Total revenue		14
Gross profit		14
Sales and marketing		(5,201)
Total operating expenses		(5,201)
Loss from operations		5,215
Loss before provision for income taxes		5,215
Net loss		$ 5,215
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)		$ 0.02
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Basis of Presentation and Sum33

Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Revenue:
Total revenue	$ 255,945	$ 182,645	[1]
As Previously Reported
Revenue:
Total revenue		182,631
Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		14
United States
Revenue:
Total revenue	184,918	146,505
United States | As Previously Reported
Revenue:
Total revenue		146,494
United States | Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		11
Rest of the world
Revenue:
Total revenue	$ 71,027	36,140
Rest of the world | As Previously Reported
Revenue:
Total revenue		36,137
Rest of the world | Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		$ 3
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Basis of Presentation and Sum34

Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net loss	$ (64,304)	$ (57,159)	[1],[2],[3]
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Deferred commissions	1,269	(1,367)	[1]
Accrued compensation and other liabilities	(29,881)	(24,194)	[1]
Deferred revenue	14,510	8,384	[1]
Cash used in operating activities	18,596	(14,301)	[1]
Cash, cash equivalents and restricted cash, beginning of period	258,820	196,409	[1]
Cash, cash equivalents and restricted cash, end of period	$ 751,639	181,491	[1]
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net loss		(62,374)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Deferred commissions		(362)
Accrued compensation and other liabilities		(19,998)
Deferred revenue		8,398
Cash used in operating activities		(14,301)
Cash, cash equivalents and restricted cash, beginning of period		183,675
Cash, cash equivalents and restricted cash, end of period		168,757
Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net loss		5,215
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Deferred commissions		(1,005)
Accrued compensation and other liabilities		(4,196)
Deferred revenue		(14)
Cash used in operating activities		0
Adjustment | Accounting Standards Update 2016-18
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Cash, cash equivalents and restricted cash, beginning of period		12,734
Cash, cash equivalents and restricted cash, end of period		$ 12,734
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Financial Instruments - Summary

Financial Instruments - Summary of Cash Equivalents, Marketable Securities and Restricted Cash by Significant Investment Categories (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 375,869	$ 365,378
Gross Unrealized Gains	77	116
Gross Unrealized Losses	(2,710)	(2,033)
Fair Value	397,983	395,518
Cash Equivalents	18,667	27,466
Marketable Securities	362,817	353,289	[1]
Restricted Cash	16,499	14,763
Money market accounts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	24,747	32,057
Cash Equivalents	8,248	17,294
Marketable Securities	0	0
Restricted Cash	16,499	14,763
U.S. government treasury notes | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	146,112	131,643
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(774)	(651)
Fair Value	145,339	130,992
Cash Equivalents	10,419	10,172
Marketable Securities	134,920	120,820
Restricted Cash	0	0
U.S. government agencies | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	40,674	47,229
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(390)	(333)
Fair Value	40,284	46,896
Cash Equivalents	0	0
Marketable Securities	40,284	46,896
Restricted Cash	0	0
Corporate debt securities | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	189,083	186,506
Gross Unrealized Gains	76	116
Gross Unrealized Losses	(1,546)	(1,049)
Fair Value	187,613	185,573
Cash Equivalents	0	0
Marketable Securities	187,613	185,573
Restricted Cash	$ 0	$ 0
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Financial Instruments - Schedul

Financial Instruments - Schedule of Amortized Cost and Estimated Fair Value of Marketable Securities by Contractual Maturity (Details) $ in Thousands	Apr. 30, 2018USD ($)
Investments, Debt and Equity Securities [Abstract]
Due within one year, Amortized Cost	$ 208,672
Due in one to five years, Amortized Cost	156,778
Total, Amortized Cost	365,450
Due within one year, Fair Value	207,951
Due in one to five years, Fair Value	154,866
Total, Fair Value	$ 362,817

Financial Instruments - Sched37

Financial Instruments - Schedule of Gross Unrealized Losses and Fair Values for Investments that were in Continuous Unrealized Loss Position for Less Than 12 Months, Aggregated by Investments Category (Details) $ in Thousands	Apr. 30, 2018USD ($)
Fair Value
Less than 12 months	$ 229,033
Greater than 12 months	97,577
Total	326,610
Unrealized Loss
Less than 12 months	(1,701)
Greater than 12 months	(1,009)
Total	(2,710)
U.S. government treasury notes
Fair Value
Less than 12 months	93,195
Greater than 12 months	40,159
Total	133,354
Unrealized Loss
Less than 12 months	(323)
Greater than 12 months	(451)
Total	(774)
U.S. government agencies
Fair Value
Less than 12 months	16,216
Greater than 12 months	24,069
Total	40,285
Unrealized Loss
Less than 12 months	(190)
Greater than 12 months	(200)
Total	(390)
Corporate debt securities
Fair Value
Less than 12 months	119,622
Greater than 12 months	33,349
Total	152,971
Unrealized Loss
Less than 12 months	(1,188)
Greater than 12 months	(358)
Total	$ (1,546)

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Balance Sheet Components Disclosure [Abstract]
Raw materials	$ 124	$ 1,181
Finished goods	38,416	33,316
Inventory	$ 38,540	$ 34,497

Balance Sheet Components - Sc39

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Property Plant And Equipment [Line Items]
Total property and equipment	$ 254,291	$ 235,035
Less: accumulated depreciation and amortization	(160,011)	(145,893)
Property and equipment, net	94,280	89,142	[1]
Test equipment
Property Plant And Equipment [Line Items]
Total property and equipment	148,444	142,311
Computer equipment and software
Property Plant And Equipment [Line Items]
Total property and equipment	82,102	72,329
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	5,611	5,363
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 18,134	$ 15,032
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Balance Sheet Components Disclosure [Abstract]
Depreciation and amortization	$ 16	$ 14.4
Intangible assets amortization expense	$ 0.4	$ 0.4
Finite-Lived Intangible Assets [Line Items]
Weighted-average remaining useful life	3 years 1 month 6 days

Balance Sheet Components - Sc41

Balance Sheet Components - Schedule of Intangible Assets, Net (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 4,681	$ 5,057	[1]
Technology patents
Finite-Lived Intangible Assets [Line Items]
Technology patents	10,125	10,125
Accumulated amortization	(5,444)	(5,068)
Intangible assets, net	$ 4,681	$ 5,057
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Balance Sheet Components - Sc42

Balance Sheet Components - Schedule of Expected Amortization Expenses for Intangible Assets (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018	[1]
Balance Sheet Components Disclosure [Abstract]
Remainder of 2019	$ 1,128
2,020	1,504
2,021	1,504
2,022	545
Intangible assets, net	$ 4,681	$ 5,057
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Balance Sheet Components - Sc43

Balance Sheet Components - Schedule of Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Balance Sheet Components Disclosure [Abstract]
Taxes payable	$ 3,790	$ 4,052
Accrued marketing	4,703	5,928
Accrued travel and entertainment expenses	4,119	4,386
Other accrued liabilities	13,017	12,463
Total accrued expenses and other liabilities	$ 25,629	$ 26,829

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 30, 2018USD ($)dayshares$ / shares	Apr. 30, 2018USD ($)$ / shares	Apr. 30, 2017USD ($)	[1]	Apr. 04, 2018$ / shares
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs		$ 562,062	$ 0
Debt issuance costs, net of amortization	$ 12,900	$ 12,900
Closing price of stock (in dollars per share) | $ / shares	$ 20.23	$ 20.23
Payment to enter into agreement		$ 64,630	$ 0
Capped Call
Debt Instrument [Line Items]
Payment to enter into agreement	$ 64,600
Convertible Senior Notes
Debt Instrument [Line Items]
Debt issuance costs, net of amortization	9,772	9,772
Additional Paid-in Capital
Debt Instrument [Line Items]
Debt issuance costs, net of amortization	$ 3,068	$ 3,068
Class A
Debt Instrument [Line Items]
Closing price of stock (in dollars per share) | $ / shares	$ 20.23	$ 20.23			$ 19.83
Class A | Capped Call
Debt Instrument [Line Items]
Exercise price (in dollars per share) | $ / shares	$ 39.66	$ 39.66
Exercise price premium percentage over last reported sales price					100.00%
Convertible Senior Notes
Debt Instrument [Line Items]
Principal amount	$ 575,000	$ 575,000
Interest rate	0.125%	0.125%
Proceeds from issuance of convertible senior notes, net of issuance costs	$ 562,100
Conversion percentage of principal amount plus accrued and unpaid contingent interest	100.00%	100.00%
Convertible debt, fair value based on the closing trading price per $100 of the Notes	$ 595,200	$ 595,200
If-converted value	$ 442,700	$ 442,700
Convertible Senior Notes | Class A
Debt Instrument [Line Items]
Number of convertible shares at initial conversion rate (in share) | shares	21,884,155
Conversion ratio (in shares per $1,000 principal amount)	38.0594
Conversion price (in dollars per share) | $ / shares	$ 26.27	$ 26.27
Redemption percentage of principal amount of Notes to be redeemed	100.00%
Convertible Senior Notes | Class A | Any Fiscal Quarter Commencing After The Fiscal Quarter Ending On July 31, 2018
Debt Instrument [Line Items]
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Threshold percentage of stock price trigger	130.00%
Convertible Senior Notes | Class A | Five Business Day Period After Any Five Consecutive Trading Day Period
Debt Instrument [Line Items]
Threshold consecutive trading days | day	5
Threshold percentage of stock price trigger	98.00%
Threshold business days | day	5
Convertible Senior Notes | Class A | Immediately Preceding The Date On Which We Provide Notice Of Redemption
Debt Instrument [Line Items]
Threshold trading days | day	2
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018

Convertible Senior Notes - Allo

Convertible Senior Notes - Allocation of Notes (Details) $ in Thousands	Apr. 30, 2018USD ($)
Liability:
Less: debt issuance costs, net of amortization	$ (12,900)
Stockholders' equity:
Less: debt issuance costs	(12,900)
Convertible Senior Notes
Liability:
Principal	575,000
Less: debt discount, net of amortization	(134,976)
Less: debt issuance costs, net of amortization	(9,772)
Net carrying amount of the Notes	430,252
Stockholders' equity:
Less: debt issuance costs	(9,772)
Additional Paid-in Capital
Liability:
Less: debt issuance costs, net of amortization	(3,068)
Stockholders' equity:
Allocated value of the conversion feature	136,333
Less: debt issuance costs	(3,068)
Additional paid-in capital	$ 133,265

Convertible Senior Notes - Inte

Convertible Senior Notes - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	[1]
Debt Instrument [Line Items]
Total amortization of debt discount and debt issuance costs	$ 1,455	$ 0
Convertible Senior Notes
Debt Instrument [Line Items]
Amortization of debt discount	1,357
Amortization of debt issuance costs	98
Total amortization of debt discount and debt issuance costs	1,455
Contractual interest expense	43
Total interest expense related to the Notes	$ 1,498
Effective interest rate of the liability component	5.60%
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	Apr. 30, 2018	Mar. 31, 2018	Jan. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Base rent obligation	$ 154,900,000		$ 113,000,000
Lessee, Lease, Description [Line Items]
Outstanding letters of credit	$ 11,500,000		$ 9,600,000
Letter of Credit
Lessee, Lease, Description [Line Items]
Principal amount		$ 1,500,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended
	Apr. 30, 2018USD ($)class$ / sharesshares	Apr. 04, 2018$ / shares	Jan. 31, 2018$ / sharesshares	[1]
Class Of Stock [Line Items]
Preferred stock, shares authorized (in shares)	20,000,000		20,000,000
Preferred stock, shares issued (in shares)	0		0
Preferred stock, shares outstanding (in shares)	0		0
Number of classes of stock | class	2
Common stock, shares authorized (in shares)	2,250,000,000		2,250,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001		$ 0.0001
Common stock, shares issued (in shares)	229,596,000		220,979,000
Common stock, shares outstanding (in shares)	229,596,000		220,979,000
Closing price of stock (in dollars per share) | $ / shares	$ 20.23
Class A
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)	2,000,000,000		2,000,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001		$ 0.0001
Common stock, shares issued (in shares)	164,207,114		129,502,000
Common stock, shares outstanding (in shares)	164,207,114		129,502,000
Stock repurchased and retired during period (in shares)	1,008,573
Stock repurchased and retired during period, value | $	$ 20
Closing price of stock (in dollars per share) | $ / shares	$ 20.23	$ 19.83
Class B
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)	250,000,000		250,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001		$ 0.0001
Common stock, shares issued (in shares)	65,389,256		91,477,000
Common stock, shares outstanding (in shares)	65,389,256		91,477,000
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details)	Mar. 16, 2016	Aug. 31, 2015USD ($)periodshares	Apr. 30, 2018USD ($)planshares	Apr. 30, 2017USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity incentive plans | plan			2
Total stock-based compensation expense			$ 43,955,000	$ 32,219,000
Compensation cost, weighted average term			2 years 2 months 12 days
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards of vest expire period (no later than)			10 years
2015 Equity Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price as percentage of fair market value of common stock			100.00%
Equity awards of vest period			2 years
2015 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards of vest period			4 years
2015 Equity Incentive Plan | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares initially reserved for issuance (in shares) | shares			27,000,000
Increase in shares reserved by percentage of capital stock			5.00%
2015 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan offering period	24 months
Number of purchase periods | period		4
Purchase period, term		6 months
Total stock-based compensation expense			$ 6,700,000	4,100,000
Unrecognized stock-based compensation expense			$ 32,600,000
Compensation cost, weighted average term			1 year 1 month 6 days
2015 Employee Stock Purchase Plan | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares reserved by percentage of capital stock		1.00%
Purchase price as percentage of fair market value of common stock		85.00%
Shares reserved for future issuance (in shares) | shares		3,500,000
Payroll deductions percentage		30.00%
Share cap for ESPP at purchase date (in shares) | shares		3,000
Calendar year gap for ESPP contribution amount		$ 25,000
Modification charges				$ 9,000,000

Equity Incentive Plans - Stock

Equity Incentive Plans - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 30, 2018	Jan. 31, 2017	Apr. 04, 2018	Jan. 31, 2018
Options Outstanding, Number of Shares
Beginning balance (in shares)	46,359,949
Options exercised (in shares)	(2,193,658)
Options forfeited/cancelled (in shares)	(1,019,718)
Ending balance (in shares)	43,146,573
Options Outstanding, Number of Shares, Vested and exercisable (in shares)	28,635,271
Options Outstanding, Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.75
Options exercised (in dollars per share)	4.40
Options forfeited/cancelled (in dollars per share)	8.25
Ending balance (in dollars per share)	7.91
Weighted Average Exercise Price, Vested and exercisable (in dollars per share)	$ 5.66
Weighted- Average Remaining Contractual Life
Weighted Average Remaining Contractual Life	6 years 1 month 6 days	6 years 3 months 18 days
Weighted Average Remaining Contractual Life, Vested and exercisable	5 years 7 months 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 531,452			$ 574,224
Aggregate Intrinsic Value, Vested and exercisable	$ 417,279
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of stock (in dollars per share)	$ 20.23
Unrecognized compensation cost, stock options	$ 60,400
Compensation cost, weighted average term	2 years 2 months 12 days
Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of stock (in dollars per share)	$ 20.23		$ 19.83

Equity Incentive Plans - Restri

Equity Incentive Plans - Restricted Stock Units (Details) - USD ($)	1 Months Ended		3 Months Ended
	Aug. 31, 2017	Mar. 30, 2017	Apr. 30, 2018	Apr. 30, 2017	Jan. 31, 2018
Weighted-Average Grant Date Fair Value
Compensation cost, weighted average term			2 years 2 months 12 days
Stock-based compensation expense			$ 43,955,000	$ 32,219,000
Restricted Stock Units
Number of Restricted Stock Units Outstanding
Unvested, Beginning balance (in shares)			17,682,646
Granted (in shares)			6,364,772
Vested (in shares)			(2,013,408)
Forfeited (in shares)			(437,921)
Converted (in shares)			(1,142,838)
Unvested, Ending balance (in shares)			20,453,251
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share)			$ 12.60
Granted (in dollars per share)			20.06
Vested (in dollars per share)			11.70
Forfeited (in dollars per share)			13.68
Converted (in dollars per share)			11.86
Ending balance (in dollars per share)			$ 15.01
Aggregate Intrinsic Value			$ 413,588,000		$ 356,117,000
Compensation not yet recognized			$ 275,700,000
Compensation cost, weighted average term			3 years 1 month 6 days
Performance Shares | Granted March 2017
Number of Restricted Stock Units Outstanding
Granted (in shares)		750,000
Forfeited (in shares)			(77,000)
Weighted-Average Grant Date Fair Value
Earned (in shares)			780,000
Stock-based compensation expense			$ 700,000	$ 500,000
Performance Shares | Granted March 2017 | Minimum
Number of Restricted Stock Units Outstanding
Award vesting rights, percentage		0.00%
Performance Shares | Granted March 2017 | Maximum
Number of Restricted Stock Units Outstanding
Award vesting rights, percentage		150.00%
Performance Shares | Granted August 2017
Number of Restricted Stock Units Outstanding
Granted (in shares)	464,744
Award vesting rights, percentage	100.00%
Weighted-Average Grant Date Fair Value
Stock-based compensation expense			$ 0
Performance Shares | Granted August 2017 | Minimum
Number of Restricted Stock Units Outstanding
Award vesting rights, percentage	0.00%
Performance Shares | Granted August 2017 | Maximum
Number of Restricted Stock Units Outstanding
Award vesting rights, percentage	150.00%

Equity Incentive Plans - Rest52

Equity Incentive Plans - Restricted Stock (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Mar. 31, 2018	Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 43,955	$ 32,219
Compensation cost, weighted average term	2 years 2 months 12 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	20,453,251		1,375,210	17,682,646
Compensation cost, weighted average term	3 years 1 month 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,500
Unrecognized stock-based compensation expense	$ 36,900
Compensation cost, weighted average term	2 years 10 months 24 days
Restricted Stock | Performance Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	697,116
Restricted Stock | Service Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	678,094
Restricted Stock | Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	1,933,861
Restricted Stock | Maximum | Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	180.00%
Restricted Stock | Minimum | Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	0.00%

Equity Incentive Plans - Stock-

Equity Incentive Plans - Stock-Based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 43,955	$ 32,219
Cost of revenue—product
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	608	397
Cost of revenue—support subscription
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	2,684	1,774
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	21,090	15,588
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	13,940	10,626
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,633	$ 3,834

Net Loss per Share Attributab54

Net Loss per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	[2]
Earnings Per Share [Abstract]
Net loss	$ (64,304)	$ (57,159)	[1],[3]
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	223,768	205,783
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.29)	$ (0.28)
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018
[2]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.
[3]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Net Loss per Share Attributab55

Net Loss per Share Attributable to Common Stockholders - Summary of Weighted-average Outstanding Shares Excluded from Computation of Diluted Net Loss per Share Attributable to Common Stockholders (Details) - shares shares in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount (in shares)	66,150	68,343
Stock options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount (in shares)	44,996	55,895
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount (in shares)	18,999	11,722
Restricted stock and early exercised stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount (in shares)	1,685	390
Employee stock purchase plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount (in shares)	470	336

Segment Information - Additiona

Segment Information - Additional Information (Details)	3 Months Ended
	Apr. 30, 2018segment
Segment Reporting [Abstract]
Number of business activity	1
Number of reportable segments	1

Segment Information - Schedule

Segment Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 255,945	$ 182,645	[1]
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	184,918	146,505
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 71,027	$ 36,140
[1]	* Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

Segment Information - Schedul58

Segment Information - Schedule of Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018
Revenues From External Customers And Long Lived Assets [Line Items]
Total long-lived assets	$ 94,280	$ 89,142	[1]
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total long-lived assets	90,203	85,430
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total long-lived assets	$ 4,077	$ 3,712
[1]	*Prior period information has been adjusted to reflect the adoption impact of Accounting Standards Codification 606, Revenue from Contracts with Customers (ASC 606), which we adopted on February 1, 2018.