Workday (WDAY) 10-K 14 Mar 18 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) shares in Millions, $ in Billions	12 Months Ended
	Jan. 31, 2018	Feb. 28, 2018	Jul. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	WDAY
Entity Registrant Name	Workday, Inc.
Entity Central Index Key	1,327,811
Current Fiscal Year End Date	--01-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		212
Entity Public Float			$ 13.8

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Jan. 31, 2018	Jan. 31, 2017
Current assets:
Cash and cash equivalents		$ 1,134,355	$ 539,923	[1]
Marketable securities		2,133,495	1,456,822	[1]
Trade and other receivables, net of allowance for doubtful accounts of $2,212 and $2,102		528,208	409,780	[1]
Deferred costs		63,060	51,330	[1]
Prepaid expenses and other current assets		97,860	66,590	[1]
Total current assets		3,956,978	2,524,445	[1]
Property and equipment, net		546,609	365,877	[1]
Deferred costs, noncurrent		140,509	117,249	[1]
Acquisition-related intangible assets, net		34,234	48,787	[1]
Goodwill		159,376	158,354	[1]
Other assets		109,718	53,570	[1]
Total assets		4,947,424	3,268,282	[1]
Current liabilities:
Accounts payable		20,998	26,824	[1]
Accrued expenses and other current liabilities		121,879	61,582	[1]
Accrued compensation		148,247	110,625	[1]
Unearned revenue		1,426,241	1,086,212	[1]
Current portion of convertible senior notes, net		341,509	0	[1]
Total current liabilities		2,058,874	1,285,243	[1]
Convertible senior notes, net		1,149,845	534,423	[1]
Unearned revenue, noncurrent		110,906	135,331	[1]
Other liabilities		47,434	36,677	[1]
Total liabilities		3,367,059	1,991,674	[1]
Commitments and contingencies (Note 12)				[1]
Stockholders’ equity:
Preferred stock, $0.001 par value; 10 million shares authorized as of January 31, 2018 and 2017; no shares issued and outstanding as of January 31, 2018 and 2017		0	0	[1]
Additional paid-in capital		3,354,423	2,681,200	[1]
Accumulated other comprehensive income (loss)		(46,413)	2,071	[1]
Accumulated deficit		(1,727,856)	(1,406,865)	[1]
Total stockholders’ equity	[1]	1,580,365	1,276,608
Total liabilities and stockholders’ equity		4,947,424	3,268,282	[1]
Class A Common Stock
Stockholders’ equity:
Common stock, value		142	127	[1]
Class B Common Stock
Stockholders’ equity:
Common stock, value		$ 69	$ 75	[1]
[1]	See Note 2 for a summary of adjustments.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Net of allowance for doubtful accounts	$ 2,212	$ 2,102
Preferred stock, par value (dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A Common Stock
Common stock, par value per share (dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	142,000,000	127,000,000
Common stock, shares outstanding	142,000,000	127,000,000
Class B Common Stock
Common stock, par value per share (dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	240,000,000	240,000,000
Common stock, shares issued	70,000,000	76,000,000
Common stock, shares outstanding	70,000,000	76,000,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Revenues:
Subscription services		$ 1,787,833	$ 1,290,733	[1]	$ 920,196	[1]
Professional services		355,217	283,707	[1]	236,494	[1]
Total revenues		2,143,050	1,574,440	[1]	1,156,690	[1]
Costs and expenses:
Costs of subscription services	[2]	273,461	213,389	[1]	149,869	[1]
Costs of professional services	[2]	355,952	270,156	[1]	224,558	[1]
Product development	[2]	910,584	680,531	[1]	469,944	[1]
Sales and marketing	[2]	683,367	565,328	[1]	413,530	[1]
General and administrative	[2]	222,909	198,122	[1]	148,578	[1]
Total costs and expenses	[2]	2,446,273	1,927,526	[1]	1,406,479	[1]
Operating loss		(303,223)	(353,086)	[1]	(249,789)	[1]
Other income (expense), net		(11,563)	(32,427)	[1]	(24,242)	[1]
Loss before provision for (benefit from) income taxes		(314,786)	(385,513)	[1]	(274,031)	[1]
Provision for (benefit from) income taxes		6,436	(814)	[1]	1,017	[1]
Net loss	[1]	(321,222)	(384,699)		(275,048)
Net loss attributable to Class A and Class B common stockholders		$ (321,222)	$ (384,699)	[1]	$ (275,048)	[1]
Net loss per share attributable to Class A and Class B common stockholders, basic and diluted (dollars per share)		$ (1.55)	$ (1.94)	[1]	$ (1.45)	[1]
Weighted-average shares used to compute net loss per share attributable to Class A and Class B common stockholders (in shares)		207,774	198,214	[1]	190,016	[1]
[1]	See Note 2 for a summary of adjustments.
[2]	Costs and expenses include share-based compensation expenses as follows: Costs of subscription services $26,280 $20,773 $12,060 Costs of professional services $37,592 $26,833 $19,526 Product development $229,819 $166,529 $109,362 Sales and marketing $100,762 $86,229 $51,617 General and administrative $83,972 $78,265 $57,405

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Costs of subscription services
Allocated share-based compensation expense	$ 26,280	$ 20,773	$ 12,060
Costs of professional services
Allocated share-based compensation expense	37,592	26,833	19,526
Product development
Allocated share-based compensation expense	229,819	166,529	109,362
Sales and marketing
Allocated share-based compensation expense	100,762	86,229	51,617
General and administrative
Allocated share-based compensation expense	$ 83,972	$ 78,265	$ 57,405

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	[1]	$ (321,222)	$ (384,699)		$ (275,048)
Other comprehensive income (loss), net of tax:
Net change in foreign currency translation adjustment		1,581	150	[1]	(3,158)	[1]
Net change in unrealized gains (losses) on available-for-sale investments		(2,687)	(388)	[1]	(842)	[1]
Net change in market value of effective foreign currency forward exchange contracts		(47,378)	1,510	[1]	4,939	[1]
Other comprehensive income (loss), net of tax:	[1]	(48,484)	1,272		939
Comprehensive loss		$ (369,706)	$ (383,427)	[1]	$ (274,109)	[1]
[1]	See Note 2 for a summary of adjustments.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Cash flows from operating activities
Net loss	[1]	$ (321,222)	$ (384,699)		$ (275,048)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization		136,974	115,885	[1]	85,939	[1]
Share-based compensation expenses		478,425	372,272	[1]	249,970	[1]
Amortization of deferred costs		57,562	45,345	[1]	36,016	[1]
Amortization of debt discount and issuance costs		43,916	26,947	[1]	25,518	[1]
Gain on sale of cost method investment		(720)	(65)	[1]	(3,220)	[1]
Impairment of cost method investment		692	15,000	[1]	0	[1]
Other		(9,602)	(1,982)	[1]	1,047	[1]
Changes in operating assets and liabilities, net of business combinations:
Trade and other receivables, net		(114,613)	(91,755)	[1]	(115,776)	[1]
Deferred costs		(92,552)	(82,848)	[1]	(66,964)	[1]
Prepaid expenses and other assets		(68,983)	(16,794)	[1]	(20,121)	[1]
Accounts payable		(7,249)	6,336	[1]	6,824	[1]
Accrued expense and other liabilities		47,515	23,367	[1]	59,724	[1]
Unearned revenue		315,584	323,617	[1]	274,728	[1]
Net cash provided by (used in) operating activities		465,727	350,626	[1]	258,637	[1]
Cash flows from investing activities
Purchases of marketable securities		(2,515,997)	(1,917,238)	[1]	(2,125,841)	[1]
Maturities of marketable securities		1,591,554	1,986,031	[1]	1,901,858	[1]
Sales of available-for-sale securities		243,727	133,292	[1]	102,711	[1]
Business combinations, net of cash acquired		(5,744)	(147,879)	[1]	(31,436)	[1]
Owned real estate projects		(124,811)	(106,997)	[1]	0	[1]
Capital expenditures, excluding owned real estate projects		(141,536)	(120,813)	[1]	(133,667)	[1]
Purchases of cost method investments		(16,199)	(300)	[1]	(16,550)	[1]
Sales and maturities of cost method investments		1,026	5,315	[1]	3,538	[1]
Purchase of other intangible assets		(11,000)	0	[1]	0	[1]
Other		0	(296)	[1]	(760)	[1]
Net cash provided by (used in) investing activities		(978,980)	(168,885)	[1]	(300,147)	[1]
Cash flows from financing activities
Proceeds from borrowings on convertible senior notes, net of issuance costs		1,132,101	0	[1]	0	[1]
Proceeds from issuance of warrants		80,805	0	[1]	0	[1]
Purchase of convertible senior notes hedges		(175,530)	0	[1]	0	[1]
Proceeds from issuance of common stock from employee equity plans		69,056	58,079	[1]	45,656	[1]
Other		(170)	1,602	[1]	(1,547)	[1]
Net cash provided by (used in) financing activities		1,106,262	59,681	[1]	44,109	[1]
Effect of exchange rate changes		751	385	[1]	(704)	[1]
Net increase (decrease) in cash, cash equivalents, and restricted cash		593,760	241,807	[1]	1,895	[1]
Cash, cash equivalents, and restricted cash at the beginning of period	[1]	541,894	300,087		298,192
Cash, cash equivalents, and restricted cash at the end of period		1,135,654	541,894	[1]	300,087	[1]
Supplemental cash flow data
Cash paid for interest, net of amounts capitalized		76	3,156	[1]	6,405	[1]
Cash paid for income taxes		3,418	5,315	[1]	2,124	[1]
Non-cash investing and financing activities:
Vesting of early exercised stock options	[1]	775	1,803		1,887
Purchases of property and equipment, accrued but not paid		51,545	27,696	[1]	14,052	[1]
Non-cash additions to property and equipment		$ 5,396	$ 2,094	[1]	$ 7,256	[1]
[1]	See Note 2 for a summary of adjustments.

Consolidated Statements of Cas8

Consolidated Statements of Cash Flows (Reconciliation) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017	[1]	Jan. 31, 2016	[1]
Reconciliation of cash, cash equivalents, and restricted cash as shown in the statements of cash flows
Cash and cash equivalents	$ 1,134,355	$ 539,923		$ 300,087
Restricted cash included in Other assets	1,299	1,971		0
Total cash, cash equivalents, and restricted cash	$ 1,135,654	$ 541,894		$ 300,087
[1]	See Note 2 for a summary of adjustments.

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total		Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, shares at Jan. 31, 2015				188,416,055
Balance at Jan. 31, 2015		$ 1,201,228	[1]	$ 186	$ 1,948,300	$ (140)	$ (747,118)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee equity plans (in shares)				4,103,433
Issuance of common stock under employee equity plans		45,656	[1]	$ 5	45,651
Vesting of early exercised stock options		1,887	[1]		1,887
Vested restricted stock units (in shares)				1,959,862
Vested restricted stock units		0	[1]	$ 2	(2)
Share-based compensation		249,970	[1]		249,970
Excess tax benefits from share-based compensation		1,646	[1]		1,646
Other		2	[1]		2
Other comprehensive income (loss)		939	[1]			939
Net loss	[1]	(275,048)					(275,048)
Balance, shares at Jan. 31, 2016				194,479,350
Balance at Jan. 31, 2016		1,226,280	[1]	$ 193	2,247,454	799	(1,022,166)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee equity plans (in shares)				4,379,787
Issuance of common stock under employee equity plans		58,079	[1]	$ 4	58,075
Vesting of early exercised stock options		1,803	[1]	$ 1	1,802
Vested restricted stock units (in shares)				4,084,268
Vested restricted stock units		0	[1]	$ 4	(4)
Share-based compensation		372,272	[1]		372,272
Excess tax benefits from share-based compensation		1,226	[1]		1,226
Other		375	[1]		375
Other comprehensive income (loss)		1,272	[1]			1,272
Net loss	[1]	(384,699)					(384,699)
Balance, shares at Jan. 31, 2017				202,943,405
Balance at Jan. 31, 2017		1,276,608	[1]	$ 202	2,681,200	2,071	(1,406,865)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee equity plans (in shares)				3,318,514
Issuance of common stock under employee equity plans		69,055	[1]	$ 3	69,052
Vesting of early exercised stock options		775	[1]	$ 0	775
Vested restricted stock units (in shares)				5,715,576
Vested restricted stock units		0	[1]	$ 6	(6)
Share-based compensation		478,425	[1]		478,425
Purchase of convertible senior notes hedges		(175,530)	[1]		(175,530)
Issuance of warrants		80,805	[1]		80,805
Equity component of convertible senior notes		219,702	[1]		219,702
Other comprehensive income (loss)		(48,484)	[1]			(48,484)
Net loss	[1]	(321,222)					(321,222)
Balance, shares at Jan. 31, 2018				211,977,495
Balance at Jan. 31, 2018		1,580,365	[1]	$ 211	$ 3,354,423	$ (46,413)	(1,727,856)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to Accumulated deficit related to the adoption of ASU No. 2016-09 (see Note 2)	[1]	$ 231					$ 231
[1]	See Note 2 for a summary of adjustments.

Consolidated Statements of St10

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Millions	Jan. 31, 2015USD ($)
Accounting Standards Update 2014-09
Cumulative effect adjustment to accumulated deficit	$ 75

Overview and Basis of Presentat

Overview and Basis of Presentation	12 Months Ended
	Jan. 31, 2018
Accounting Policies [Abstract]
Overview and Basis of Presentation	Overview and Basis of Presentation Company and Background Workday provides financial management, human capital management, and analytics applications designed for the world's largest companies, educational institutions, and government agencies. We offer innovative and adaptable technology focused on the consumer Internet experience and cloud delivery model. Our applications are designed for global enterprises to manage complex and dynamic operating environments. We provide our customers highly adaptable, accessible and reliable applications to manage critical business functions that enable them to optimize their financial and human capital resources. We were originally incorporated in March 2005 in Nevada and in June 2012, we reincorporated in Delaware. Fiscal Year Our fiscal year ends on January 31. References to fiscal 2018 , for example, refer to the year ended January 31, 2018 . Basis of Presentation These consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP"). The consolidated financial statements include the results of Workday, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. Effective February 1, 2017, we adopted the requirements of Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers and ASU No. 2016-18, Statement of Cash Flows, Restricted Cash as discussed in Note 2. All amounts and disclosures set forth in this Form 10-K have been updated to comply with the new standards, as indicated by the "as adjusted" footnote. Certain prior period amounts reported in our consolidated financial statements and notes thereto have been reclassified to conform to current period presentation. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenues and expenses during the reporting period. These estimates include, but are not limited to, the determination of the period of benefit for deferred commissions, certain assumptions used in the valuation of equity awards, and the fair value of assets acquired and liabilities assumed through business combinations. Actual results could differ from those estimates and such differences could be material to our consolidated financial position and results of operations. Segment Information We operate in one operating segment, cloud applications. Operating segments are defined as components of an enterprise where separate financial information is evaluated regularly by the chief operating decision maker, who is our chief executive officer, in deciding how to allocate resources and assessing performance. Our chief operating decision maker allocates resources and assesses performance based upon discrete financial information at the consolidated level.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Jan. 31, 2018
Accounting Policies [Abstract]
Accounting Standards and Significant Accounting Policies	Accounting Standards and Significant Accounting Policies Summary of Significant Accounting Policies Revenue Recognition We derive our revenues primarily from subscription services and professional services. Revenues are recognized when control of these services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services. We determine revenue recognition through the following steps: • 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 Subscription Services Revenues Subscription services revenues primarily consist of fees that provide customers access to one or more of our cloud applications for finance, human resources, and analytics, with routine customer support. Revenue is generally recognized on a ratable basis over the contract term beginning on the date that our service is made available to the customer. Our subscription contracts are generally three years or longer in length, billed annually in advance, and non-cancelable. Professional Services Revenues Professional services revenues primarily consist of fees for deployment and optimization services, as well as training. The majority of our consulting contracts are billed on a time and materials basis and revenue is recognized over time as the services are performed. For contracts billed on a fixed price basis, revenue is recognized over time based on the proportion performed. Contracts with Multiple Performance Obligations Some of our contracts with customers contain multiple performance obligations. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to the separate performance obligations on a relative standalone selling price basis. We determine the standalone selling prices based on our overall pricing objectives, taking into consideration market conditions and other factors, including the value of our contracts, the cloud applications sold, customer demographics, geographic locations, and the number and types of users within our contracts. Fair Value Measurement We measure our cash equivalents, marketable securities and foreign currency derivative contracts at fair value at each reporting period using a fair value hierarchy that requires that we 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 that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2 — Other inputs that are directly or indirectly observable in the marketplace. Level 3 — Unobservable inputs that are supported by little or no market activity. Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with maturities of three months or less at the time of purchase. Our cash equivalents primarily consist of investments in U.S. agency obligations, U.S. treasury securities, corporate bonds, commercial paper, and money market funds. Marketable Securities Our marketable securities primarily consist of investments in U.S. agency obligations, U.S. treasury securities, corporate bonds, and commercial paper. We classify our marketable securities as available-for-sale at the time of purchase and reevaluate such classification as of each balance sheet date. We consider all marketable securities as available for use in current operations, including those with maturity dates beyond one year, and therefore classify these securities as current assets in the accompanying consolidated balance sheets. All marketable securities are recorded at their estimated fair value. Unrealized gains and losses on available-for-sale securities are recorded in Accumulated other comprehensive income (loss) ("OCI"). We evaluate our investments to assess whether those in 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 and declines in value judged to be other-than-temporary are determined based on the specific identification method and are reported in Other income (expense), net on the consolidated statements of operations. If quoted prices for identical instruments are available in an active market, marketable securities are classified within Level 1 of the fair value hierarchy. If quoted prices for identical instruments in active markets are not available, fair values are estimated using quoted prices of similar instruments and are classified within Level 2 of the fair value hierarchy. To date, all of our marketable securities can be valued using one of these two methodologies. Trade and Other Receivables Trade and other receivables are primarily comprised of trade receivables that are recorded at the invoice amount, net of an allowance for doubtful accounts, which is not material. Other receivables represent unbilled receivables related to subscription and professional services contracts. Deferred Commissions Sales commissions earned by our sales force are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions for initial contracts are deferred and then amortized on a straight-line basis over a period of benefit that we have determined to be five years. We determined the period of benefit by taking into consideration our customer contracts, our technology and other factors. Sales commissions for renewal contracts are deferred and then amortized on a straight-line basis over the related contractual renewal period. Amortization expense is included in Sales and marketing expenses on the consolidated statements of operations. Derivative Financial Instruments and Hedging Activities We use derivative financial instruments to manage foreign currency risks. Derivative instruments are carried at fair value and recorded as either an asset or liability on the consolidated balance sheets. Gains and losses resulting from changes in fair value are accounted for depending on the use of the derivative and whether it is designated and qualifies for hedge accounting. For foreign currency forward contracts not designated as hedging instruments, which we use to hedge a portion of our net outstanding monetary assets and liabilities, the gains or losses are recorded in Other income (expense), net on the consolidated statements of operations in the period of change. For a derivative instrument designated as a cash flow hedge, which we use to hedge certain customer contracts denominated in foreign currencies, the change in fair value on the effective portion is recorded to OCI on our consolidated balance sheets each reporting period. The balance in OCI is subsequently reclassified to the related revenue line item on the consolidated statements of operations in the same period that the underlying revenues are earned. Our foreign currency contracts are classified within Level 2 of the fair value hierarchy because the valuation inputs are based on quoted prices and market observable data of similar instruments in active markets, such as currency spot and forward rates. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation is recorded using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the shorter of the estimated useful lives of the assets or the related lease term. Property and equipment is reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Business Combinations We use our best estimates and assumptions to assign fair value to the tangible and intangible assets acquired and liabilities assumed as of the acquisition date. Our estimates are inherently uncertain and subject to refinement. During the measurement period, which may be up to one year from the acquisition date, we may record adjustments to the fair value of these tangible and intangible assets acquired and liabilities assumed, with the corresponding offset to goodwill. In addition, uncertain tax positions and tax-related valuation allowances are initially established in connection with a business combination as of the acquisition date. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to our consolidated statements of operations. Goodwill and Acquisition-Related Intangible Assets Acquisition-related intangible assets with finite lives are typically amortized over useful lives of three to four years. Goodwill amounts are not amortized. Acquisition-related intangible assets and goodwill are tested for impairment at least annually, and more frequently upon the occurrence of certain events. Unearned Revenue Unearned revenue primarily consists of customer billings in advance of revenues being recognized from our subscription contracts. We generally invoice our customers annually in advance for our subscription services. Our typical payment terms provide that customers pay a portion of the total arrangement fee within 30 days of the contract date. Unearned revenue that is anticipated to be recognized during the succeeding twelve -month period is recorded as current unearned revenue and the remaining portion is recorded as noncurrent. Convertible Senior Notes In June 2013, we issued 0.75% convertible senior notes due July 15, 2018 ("2018 Notes") with a principal amount of $350 million . Concurrently, we issued 1.50% convertible senior notes due July 15, 2020 ("2020 Notes") with a principal amount of $250 million . In September 2017, we issued 0.25% convertible senior notes due October 1, 2022 ("2022 Notes") with a principal amount of $1.15 billion (together with the 2018 Notes and 2020 Notes, referred to as "the Notes"). In accounting for the issuance of the Notes, we separated each of the Notes into liability and equity components. The carrying amounts of the liability components were calculated by measuring the fair value of similar liabilities that do not have associated convertible features. The carrying amount of the equity components representing the conversion option were determined by deducting the fair value of the liability components from the par value of the respective Notes. These differences represent debt discounts that are amortized to interest expense over the respective terms of the Notes using the effective interest rate method. The equity components are not remeasured as long as they continue to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, we allocated the total amount of issuance costs incurred to liability and equity components based on their relative values. Issuance costs attributable to the liability components are being amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the respective terms of the Notes. The issuance costs attributable to the equity components were netted against the respective equity components in Additional paid-in capital. Advertising Expenses Advertising is expensed as incurred. Advertising expense was $43 million , $35 million , and $31 million for fiscal 2018 , 2017 , and 2016 , respectively. Share-Based Compensation We measure and recognize compensation expense for share-based awards issued to employees and non-employees, including restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs"), and purchases under the 2012 Employee Stock Purchase Plan ("ESPP"), on our consolidated statements of operations. For RSUs and PRSUs, fair value is based on the closing price of our common stock on the grant date. Compensation expense, net of estimated forfeitures, is recognized on a straight-line basis over the requisite service period. Non-employee RSUs subject to vesting are required to be periodically revalued over the requisite service period. The requisite service period of the awards is generally the same as the vesting period. For shares issued under the ESPP, fair value is estimated using the Black-Scholes option-pricing model. Compensation expense is recognized on a straight-line basis over the offering period. We determine the assumptions for the option-pricing model as follows: • Risk-Free Interest Rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date closest to the grant date for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the ESPP purchase rights. • Expected Term. The expected term represents the period that our ESPP is expected to be outstanding. The expected term for the ESPP approximates the offering period. • Volatility. The volatility is based on a blend of historical volatility and implied volatility of our common stock. Implied volatility is based on market traded options of our common stock. • Dividend Yield. The dividend yield is assumed to be zero as we have not paid and do not expect to pay dividends. Income Taxes We record a provision for income taxes for the anticipated tax consequences of the reported results of operations using the asset and liability method. Under this method, we recognize deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. We record a valuation allowance to reduce our deferred tax assets to the net amount that we believe is more likely than not to be realized. We recognize tax benefits from uncertain tax positions only if we believe that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Although we believe that we have adequately reserved for our uncertain tax positions, we can provide no assurance that the final tax outcome of these matters will not be materially different. We make adjustments to these reserves when facts and circumstances change, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on our financial condition and operating results. The provision for income taxes includes the effects of any accruals that we believe are appropriate, as well as the related net interest and penalties. Warranties and Indemnification Our cloud applications are generally warranted to perform materially in accordance with our online documentation under normal use and circumstances. Additionally, our contracts generally include provisions for indemnifying customers against liabilities if use of our cloud applications infringe a third party’s intellectual property rights. We may also incur liabilities if we breach the security, privacy and/or confidentiality obligations in our contracts. To date, we have not incurred any material costs, and we have not accrued any liabilities in the accompanying consolidated financial statements, as a result of these obligations. We have entered into service-level agreements with a majority of our customers committing to defined levels of service availability and performance and permitting those customers to receive credits or refunds for prepaid amounts related to unused subscription services or to terminate their agreements in the event that we fail to meet those levels. To date, we have not experienced any significant failures to meet defined levels of availability and performance of those agreements and, as a result, we have not accrued any liabilities related to these agreements on the consolidated financial statements. Foreign Currency Exchange The functional currency for certain of our foreign subsidiaries is the U.S. dollar, while others use local currencies. We translate the foreign functional currency financial statements to U.S dollars for those entities that do not have U.S. dollars as their functional currency using the exchange rates at the balance sheet date for assets and liabilities, the period average exchange rates for revenues and expenses, and the historical exchange rates for equity transactions. The effects of foreign currency translation adjustments are recorded in OCI as a component of stockholders' equity, and related periodic movements are summarized as a line item in our consolidated statements of comprehensive loss. Foreign currency transaction gains and losses are included in Other income (expense), net on the consolidated statements of operations. Concentrations of Risk and Significant Customers Our financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents, marketable securities, and trade and other receivables. Our deposits exceed federally insured limits. No single customer represented over 10% of trade and other receivables on the consolidated financial statements as of January 31, 2018 or 2017 . No single customer represented over 10% of total revenues for any of the periods on the consolidated financial statements. In order to reduce the risk of down-time of our cloud applications, we have established data centers in various geographic regions. We have internal procedures to restore services in the event of disaster at one of our current data center facilities. We serve our customers and users from data center facilities operated by third parties, located in Ashburn, Virginia; Atlanta, Georgia; Portland, Oregon; Dublin, Ireland; Amsterdam, the Netherlands; and Toronto, Canada. Even with these procedures for disaster recovery in place, our cloud applications could be significantly interrupted during the implementation of the procedures to restore services. In addition, we rely upon third-party hosted infrastructure partners, including Amazon Web Services ("AWS"), to serve customers and operate certain aspects of our services, such as environments for development testing, training and sales demonstrations, as well as others. Given this, any disruption of or interference at our hosted infrastructure partners would impact our operations and our business could be adversely impacted. Recently Adopted Accounting Pronouncements ASU No. 2014-09 In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, Revenue from Contracts with Customers ("Topic 606"). Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition ("Topic 605") , and requires the recognition of revenue when promised goods or services are transferred to customers in an amount that reflects the considerations to which the entity expects to be entitled to in exchange for those goods or services. Topic 606 also includes Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers , which requires the deferral of incremental costs of obtaining a contract with a customer. Collectively, we refer to Topic 606 and Subtopic 340-40 as the "new standard." We early adopted the requirements of the new standard as of February 1, 2017, utilizing the full retrospective method of transition. Adoption of the new standard resulted in changes to our accounting policies for revenue recognition, trade and other receivables, and deferred commissions. We applied the new standard using a practical expedient where the consideration allocated to the remaining performance obligations or an explanation of when we expect to recognize that amount as revenue for all reporting periods presented before the date of the initial application is not disclosed. The impact of adopting the new standard on our fiscal 2017 and fiscal 2016 revenues was not material. The primary impact of adopting the new standard relates to the deferral of incremental commission costs of obtaining subscription contracts. Under Topic 605, we deferred only direct and incremental commission costs to obtain a contract and amortized those costs on a straight-line basis over the term of the related subscription contract, which was generally three years or longer. Under the new standard, we defer all incremental commission costs to obtain the contract. We amortize these costs on a straight-line basis over a period of benefit that we have determined to be five years or the related contractual renewal period, depending on whether the contract is an initial or renewal contract, respectively. ASU No. 2016-09 In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718), which simplifies the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and classification in the statement of cash flows. As of February 1, 2017, we adopted the applicable provisions of ASU No. 2016-09 as follows: • The guidance requires excess tax benefits and tax deficiencies to be recorded as income tax benefit or expense in the statement of operations when the awards vest or are settled, and eliminates the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the statement of cash flows. We adopted the guidance prospectively effective February 1, 2017. Amounts previously recorded to Additional paid -in capital related to windfall tax benefits prior to February 1, 2017 remain in Stockholders' equity. • The guidance eliminates the requirement that excess tax benefits must be realized (through a reduction in income taxes payable) before companies can recognize them. We have applied the modified retrospective transition method upon adoption. The previously unrecognized excess tax effects were recorded as a deferred tax asset in the amount of $448.0 million , of which $447.8 million was fully offset by a valuation allowance, and the remaining $0.2 million resulted in a cumulative-effect adjustment to Accumulated deficit as of February 1, 2017. ASU No. 2016-18 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) , which requires that a statement of cash flows explain the change during the period for the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. We early adopted ASU No. 2016-18 retrospectively, effective February 1, 2017. As a result of including restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the consolidated statements of cash flows, net cash flows for fiscal 2017 increased by $2 million . We adjusted our consolidated financial statements from amounts previously reported due to the adoption of ASU No. 2014-09 and ASU No. 2016-18. Select consolidated balance sheet line items, which reflect the adoption of the new ASU's are as follows (in thousands): January 31, 2017 As Previously Reported Adjustments As Adjusted Assets Trade and other receivables, net $ 383,908 $ 25,872 a $ 409,780 Prepaid expenses and other current assets 88,336 (21,746 ) a 66,590 Deferred costs 27,537 23,793 a 51,330 Deferred costs, noncurrent 43,310 73,939 a 117,249 Liabilities Unearned revenue $ 1,097,417 $ (11,205 ) a $ 1,086,212 Unearned revenue, noncurrent 135,970 (639 ) a 135,331 Select audited consolidated statement of operations line items, which reflect the adoption of the new ASUs are as follows (in thousands, except per share data): Year ended January 31, 2017 As Previously Reported Adjustments As Adjusted Revenues: Subscription services $ 1,287,104 $ 3,629 a $ 1,290,733 Professional services 282,303 1,404 a 283,707 Total revenues 1,569,407 5,033 a 1,574,440 Costs and expenses: Sales and marketing 583,874 (18,546 ) a 565,328 Operating loss (376,665 ) 23,579 a (353,086 ) Net loss $ (408,278 ) $ 23,579 a $ (384,699 ) Net loss per share, basic and diluted $ (2.06 ) $ 0.12 a $ (1.94 ) Year ended January 31, 2016 As Previously Reported Adjustments As Adjusted Revenues: Subscription services $ 929,234 $ (9,038 ) a $ 920,196 Professional services 233,112 3,382 a 236,494 Total revenues 1,162,346 (5,656 ) a 1,156,690 Costs and expenses: Sales and marketing 434,056 (20,526 ) a 413,530 Operating loss (264,659 ) 14,870 a (249,789 ) Net loss $ (289,918 ) $ 14,870 a $ (275,048 ) Net loss per share, basic and diluted $ (1.53 ) $ 0.08 a $ (1.45 ) Select audited consolidated statement of cash flows line items, which reflect the adoption of the new ASUs are as follows (in thousands): Year ended January 31, 2017 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (408,278 ) $ 23,579 a $ (384,699 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Amortization of deferred costs 25,577 19,768 a 45,345 Changes in operating assets and liabilities: Trade and other receivables, net (88,639 ) (3,116 ) a (91,755 ) Deferred costs (44,533 ) (38,315 ) a (82,848 ) Prepaid expenses and other assets (20,847 ) 4,053 a, b (16,794 ) Unearned revenue 327,615 (3,998 ) a 323,617 Net cash provided by (used in) operating activities 348,655 1,971 b 350,626 Net increase (decrease) in cash, cash equivalents, and restricted cash 239,836 1,971 b 241,807 Cash, cash equivalents, and restricted cash at the end of period $ 539,923 $ 1,971 b $ 541,894 Year ended January 31, 2016 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (289,918 ) $ 14,870 a $ (275,048 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Amortization of deferred costs 23,477 12,539 a 36,016 Changes in operating assets and liabilities: Trade and other receivables, net (105,264 ) (10,512 ) a (115,776 ) Deferred costs (33,899 ) (33,065 ) a (66,964 ) Prepaid expenses and other assets (28,366 ) 8,245 a (20,121 ) Unearned revenue 266,805 7,923 a 274,728 Net cash provided by (used in) operating activities 258,637 — b 258,637 a Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. b Adjusted to reflect the adoption of ASU No. 2016-18, Statement of Cash Flows, Restricted Cash. Recently Issued Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10) , which requires entities to carry all investments in equity securities at fair value and recognize any changes in fair value in net income. Under the standard, equity investments that do not have readily determinable fair values and do not qualify for the net asset value practical expedient are eligible for the measurement alternative. For our equity investments in private companies, we will elect the measurement alternative, defined as cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. The guidance is effective for our fiscal year beginning February 1, 2018 on a prospective basis for the amendments related to equity securities without readily determinable fair values existing as of the date of adoption. We plan to adopt the new standard in the first quarter of fiscal 2019 and do not expect it to have a material impact on our consolidated financial statements. The impact of the new standard going forward could result in volatility in Other income (expense), net on the consolidated statements of operations in future periods due to the valuation and timing of identical or similar investments of the same issuer. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which requires the recognition of lease assets and lease liabilities on the balance sheet by lessees for those leases currently classified as operating leases under ASC Topic 840 Leases. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020. We continue to evaluate the effect of adopting this guidance on our consolidated financial statements and related disclosures and we expect our operating leases, as disclosed in Note 12, will be subject to the new standard. Upon adoption, we will recognize right-of-use assets and operating lease liabilities on our consolidated balance sheets, which will increase our total assets and total liabilities. We are evaluating the accounting, transition, and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory (Topic 740) , which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Prior to the issuance of this ASU, existing guidance prohibited the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset had been sold to an outside party. The guidance is effective for our fiscal year beginning February 1, 2018. We plan to adopt the new standard in the first quarter of fiscal 2019 and do not expect it to have a material impact on our consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815) , to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020. We are evaluating the accounting, transition, and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption. 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, which provides entities the option to reclassify tax effects stranded in accumulated other comprehensive income as a result of the 2017 Tax Cuts and Jobs Act ("the Tax Act") to retained earnings. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020 and do not expect it to have a material impact on our consolidated financial statements.

Marketable Securities

Marketable Securities	12 Months Ended
	Jan. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities At January 31, 2018 , marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Aggregate Fair Value U.S. agency obligations $ 683,551 $ — $ (1,127 ) $ 682,424 U.S. treasury securities 797,977 — (1,142 ) 796,835 Corporate bonds 470,259 16 (1,154 ) 469,121 Commercial paper 602,727 — — 602,727 Money market funds 551,804 — — 551,804 $ 3,106,318 $ 16 $ (3,423 ) $ 3,102,911 Included in cash and cash equivalents $ 969,417 $ — $ (1 ) $ 969,416 Included in marketable securities $ 2,136,901 $ 16 $ (3,422 ) $ 2,133,495 At January 31, 2017 , marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Aggregate Fair Value U.S. agency obligations $ 908,874 $ 179 $ (535 ) $ 908,518 U.S. treasury securities 192,028 48 (25 ) 192,051 Corporate bonds 290,272 42 (429 ) 289,885 Commercial paper 323,106 — — 323,106 Money market funds 24,425 — — 24,425 $ 1,738,705 $ 269 $ (989 ) $ 1,737,985 Included in cash and cash equivalents $ 281,163 $ — $ — $ 281,163 Included in marketable securities $ 1,457,542 $ 269 $ (989 ) $ 1,456,822 We do not believe the unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence, which includes our intent to hold these investments to maturity as of January 31, 2018 . The unrealized losses on marketable securities which have been in a net loss position for 12 months or more were not material as of January 31, 2018 . We sold $244 million , $133 million , and $103 million of our marketable securities during fiscal 2018 , 2017 , and 2016 , respectively, and the realized losses from the sales were immaterial.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Jan. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis and their assigned levels within the valuation hierarchy as of January 31, 2018 (in thousands): Description Level 1 Level 2 Level 3 Total U.S. agency obligations $ — $ 682,424 $ — $ 682,424 U.S. treasury securities 796,835 — — 796,835 Corporate bonds — 469,121 — 469,121 Commercial paper — 602,727 — 602,727 Money market funds 551,804 — — 551,804 Foreign currency derivative assets — 98 — 98 Total assets $ 1,348,639 $ 1,754,370 $ — $ 3,103,009 Foreign currency derivative liabilities $ — $ 32,912 $ — $ 32,912 Total liabilities $ — $ 32,912 $ — $ 32,912 The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis and their assigned levels within the valuation hierarchy as of January 31, 2017 (in thousands): Description Level 1 Level 2 Level 3 Total U.S. agency obligations $ — $ 908,518 $ — $ 908,518 U.S. treasury securities 192,051 — — 192,051 Corporate bonds — 289,885 — 289,885 Commercial paper — 323,106 — 323,106 Money market funds 24,425 — — 24,425 Foreign currency derivative assets — 7,909 — 7,909 Total assets $ 216,476 $ 1,529,418 $ — $ 1,745,894 Foreign currency derivative liabilities $ — $ 2,127 $ — $ 2,127 Total liabilities $ — $ 2,127 $ — $ 2,127 Fair Value Measurements of Other Financial Instruments The following table presents the carrying amounts and estimated fair values of our financial instruments that are not recorded at fair value on the consolidated balance sheets (in thousands): January 31, 2018 January 31, 2017 Net Carrying Amount Estimated Net Carrying Amount Estimated 0.75% Convertible senior notes $ 341,509 $ 504,994 $ 323,570 $ 402,259 1.50% Convertible senior notes 221,378 385,550 210,853 310,470 0.25% Convertible senior notes 928,467 1,200,577 — — The estimated fair values of the Notes, which we have classified as Level 2 financial instruments, were determined based on the quoted bid prices of the Notes in an over-the-counter market as of the last day of trading for fiscal 2018 and 2017. The if-converted values of the 2018 and 2020 Notes exceeded the principal amounts by $154 million and $117 million , respectively. The if-converted value of the 2022 Notes was less than the principal amount by $213 million . The if-converted values were determined based on the closing price of our common stock of $119.89 on January 31, 2018 . For further information, see Note 11.

Deferred Costs

Deferred Costs	12 Months Ended
	Jan. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs	Deferred Costs Deferred costs, which primarily consist of deferred sales commissions, were $204 million and $169 million as of January 31, 2018 and 2017 , respectively. Amortization expense for the deferred costs was $58 million , $45 million , and $36 million for fiscal 2018 , 2017 , and 2016 , respectively. There was no impairment loss in relation to the costs capitalized for the periods presented.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Jan. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): January 31, 2018 2017 Land $ 8,451 $ 6,592 Buildings 255,093 115,302 Computers, equipment, and software 411,177 323,311 Computers, equipment, and software acquired under capital leases 13,848 18,298 Furniture and fixtures 34,809 24,462 Leasehold improvements 132,209 108,673 Property and equipment, gross (1) 855,587 596,638 Less accumulated depreciation and amortization (308,978 ) (230,761 ) Property and equipment, net $ 546,609 $ 365,877 (1) Property and equipment, gross includes construction-in-progress for owned real estate projects of $177 million and $115 million that have not yet been placed in service as of January 31, 2018 and 2017 , respectively. During fiscal 2017 we purchased real property located in Pleasanton, California which includes two office buildings totaling approximately 267,000 square feet, land, and parking structures. Depreciation expense was $115 million , $92 million , and $71 million for fiscal 2018 , 2017 , and 2016 , respectively. Interest costs capitalized to property and equipment totaled $8 million and $3 million for fiscal 2018 and 2017 , respectively.

Business Combinations

Business Combinations	12 Months Ended
	Jan. 31, 2018
Business Combinations [Abstract]
Business Combinations	Business Combinations In the fourth quarter of fiscal 2018, we completed an acquisition resulting in an increase of $5 million and $1 million in acquired developed technology and goodwill, respectively. In fiscal 2017 we acquired two businesses in order to expand our product and service offerings. We have included the financial results of the acquired businesses in our consolidated financial statements from the respective acquisition dates. The consideration paid for these acquisitions was $148 million , net of cash acquired. The following table summarizes the estimated fair values of assets acquired and liabilities assumed in the business combinations during fiscal 2017 (in thousands): Cash and cash equivalents $ 3,390 Other tangible assets 3,466 Acquired developed technology 45,039 Customer relationship assets 1,000 Accounts payable and other liabilities (3,256 ) Unearned revenue (6,000 ) Net assets acquired 43,639 Goodwill 107,658 Total purchase consideration $ 151,297 The excess of purchase consideration over the fair value of net tangible and identifiable intangible assets acquired was recorded as goodwill. The goodwill balance is not deductible for U.S. income tax purposes. Pro forma results of operations for these acquisitions have not been presented because they are not material to the consolidated results of operations, either individually or in aggregate.

Acquisition-related Intangible

Acquisition-related Intangible Assets, Net	12 Months Ended
	Jan. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Acquisition-related Intangible Assets, Net	Acquisition-related Intangible Assets, Net Acquisition-related intangible assets, net consisted of the following (in thousands): January 31, 2018 2017 Acquired developed technology $ 69,700 $ 64,900 Customer relationship assets 1,000 1,000 70,700 65,900 Less accumulated amortization (36,466 ) (17,113 ) Acquisition-related intangible assets, net $ 34,234 $ 48,787 Amortization expense related to acquired developed technology and customer relationship assets was $19 million , $13 million , and $3 million for fiscal 2018 , 2017 , and 2016 , respectively. As of January 31, 2018 , our future estimated amortization expense related to the acquired developed technology and customer relationship assets is as follows (in thousands): Fiscal Period: 2019 $ 20,086 2020 11,481 2021 1,517 2022 1,150 Total $ 34,234

Other Assets

Other Assets	12 Months Ended
	Jan. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Other Assets Other assets consisted of the following (in thousands): January 31, 2018 2017 Cost method investments $ 29,205 $ 14,004 Prepayments for computing infrastructure platform 13,588 — Technology patents, net 11,217 2,098 Acquired land leasehold interest, net 9,570 9,676 Deposits 4,492 3,488 Net deferred tax assets 1,884 4,336 Other 39,762 19,968 Total $ 109,718 $ 53,570 Our cost method investments include investments in private companies in which we do not have the ability to exert significant influence. The investments are tested for impairment at least annually, and more frequently upon the occurrence of certain events. We recorded $1 million and $15 million other-than-temporary impairments for our cost method investments during fiscal 2018 and 2017, respectively. Intangible assets with estimable useful lives, including acquired land leasehold interest and technology patents, are amortized on straight-line basis over their useful lives. As of January 31, 2018, the future estimated amortization expense related to the acquired land leasehold interest and technology patents is as follows (in thousands): 2019 $ 1,678 2020 1,621 2021 1,459 2022 1,242 2023 1,137 Thereafter 13,650 $ 20,787

Derivative Instruments

Derivative Instruments	12 Months Ended
	Jan. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments We conduct business on a global basis in multiple foreign currencies, subjecting Workday to foreign currency risk. To mitigate this risk, we utilize hedging contracts as described below. We do not enter into any derivatives for trading or speculative purposes. Cash Flow Hedges We are exposed to foreign currency fluctuations resulting from customer contracts denominated in foreign currencies. We have a hedging program in which we enter into foreign currency forward contracts related to certain customer contracts. We designate these forward contracts as cash flow hedging instruments as the accounting criteria for such designation have been met. The effective portion of the gains or losses resulting from changes in the fair value of these hedges is recorded in OCI on the consolidated balance sheets and will be subsequently reclassified to the related revenue line item on the consolidated statements of operations in the same period that the underlying revenues are earned. The changes in value of these contracts resulting from changes in forward points are excluded from the assessment of hedge effectiveness and are recorded as incurred in Other income (expense), net on the consolidated statements of operations. Cash flows from such forward contracts are classified as operating activities. As of January 31, 2018 and 2017 , we had outstanding foreign currency forward contracts designated as cash flow hedges with total notional values of $549 million and $252 million , respectively. All contracts have maturities not greater than 36 months . The notional value represents the amount that will be bought or sold upon maturity of the forward contract. Foreign Currency Forward Contracts not Designated as Hedges We also enter into foreign currency forward contracts to hedge a portion of our net outstanding monetary assets and liabilities. These forward contracts are not designated as hedging instruments under applicable accounting guidance, and therefore all changes in the fair value of the forward contracts are recorded in Other income (expense), net on the consolidated statements of operations. These forward contracts are intended to offset the foreign currency gains or losses associated with the underlying monetary assets and liabilities. Cash flows from such forward contracts are classified as operating activities. As of January 31, 2018 and 2017 , we had outstanding forward contracts with total notional values of $75 million and $51 million , respectively. The fair values of outstanding derivative instruments were as follows (in thousands): Consolidated Balance Sheets Location January 31, 2018 2017 Derivative Assets: Foreign currency forward contracts designated as cash flow hedges Prepaid expenses and other current assets $ 15 $ 7,121 Foreign currency forward contracts designated as cash flow hedges Other assets 4 28 Foreign currency forward contracts not designated as hedges Prepaid expenses and other current assets 79 760 Total Derivative Assets $ 98 $ 7,909 Derivative Liabilities: Foreign currency forward contracts designated as cash flow hedges Accrued expenses and other current liabilities $ 18,355 $ 1,605 Foreign currency forward contracts designated as cash flow hedges Other liabilities 11,650 — Foreign currency forward contracts not designated as hedges Accrued expenses and other current liabilities 2,805 522 Foreign currency forward contracts not designated as hedges Other liabilities 102 — Total Derivative Liabilities $ 32,912 $ 2,127 Gains (losses) associated with foreign currency forward contracts designated as cash flow hedges were as follows (in thousands): Consolidated Statements of Operations and Statements of Comprehensive Loss Locations January 31, 2018 2017 2016 Gains (losses) recognized in OCI (effective portion) (1) Net change in market value of effective foreign currency forward exchange contracts $ (45,869 ) $ 2,145 $ 4,942 Gains (losses) reclassified from OCI into income (effective portion) Revenues 1,509 635 3 Gains (losses) recognized in income (amount excluded from effectiveness testing and ineffective portion) Other income (expense), net 1,607 1,386 148 (1) Of the total effective portion of foreign currency forward contracts designated as cash flow hedges as of January 31, 2018 , net losses of $10 million are expected to be reclassified out of OCI within the next 12 months. Gains (losses) associated with foreign currency forward contracts not designated as cash flow hedges were as follows (in thousands): Consolidated Statements of Operations Location January 31, Derivative Type 2018 2017 2016 Foreign currency forward contracts not designated as hedges Other income (expense), net $ (5,641 ) $ 662 $ 876 We are subject to master netting agreements with certain counterparties of the foreign exchange contracts, under which we are permitted to net settle transactions of the same currency with a single net amount payable by one party to the other. It is our policy to present the derivatives gross on the consolidated balance sheets. Our foreign currency forward contracts are not subject to any credit contingent features or collateral requirements. We manage our exposure to counterparty concentration risk by entering into contracts with a diversified group of major financial institutions and by actively monitoring outstanding positions. As of January 31, 2018 , information related to these offsetting arrangements was as follows (in thousands): Gross Amounts of Recognized Assets Gross Amounts Offset on the Consolidated Balance Sheets Net Amounts of Assets Presented on the Consolidated Balance Sheets Gross Amounts Not Offset on the Consolidated Balance Sheets Net Assets Exposed Financial Instruments Cash Collateral Received Derivative Assets Counterparty A $ 64 $ — $ 64 $ (64 ) $ — $ — Counterparty B 23 — 23 (23 ) — — Counterparty C 11 — 11 (11 ) — — Total $ 98 $ — $ 98 $ (98 ) $ — $ — Gross Amounts of Recognized Liabilities Gross Amounts Offset on the Consolidated Balance Sheets Net Amounts of Liabilities Presented on the Consolidated Balance Sheets Gross Amounts Not Offset on the Consolidated Balance Sheets Net Liabilities Exposed Financial Instruments Cash Collateral Pledged Derivative Liabilities Counterparty A $ 10,267 $ — $ 10,267 $ (64 ) $ — $ 10,203 Counterparty B 16,993 — 16,993 (23 ) — 16,970 Counterparty C 5,652 — 5,652 (11 ) — 5,641 Total $ 32,912 $ — $ 32,912 $ (98 ) $ — $ 32,814

Convertible Senior Notes, Net

Convertible Senior Notes, Net	12 Months Ended
	Jan. 31, 2018
Debt Disclosure [Abstract]
Convertible Senior Notes, Net	Convertible Senior Notes, Net Convertible Senior Notes In June 2013, we issued 0.75% convertible senior notes due July 15, 2018 with a principal amount of $350 million . The 2018 Notes are unsecured, unsubordinated obligations, and interest is payable in cash in arrears at a fixed rate of 0.75% on January 15 and July 15 of each year. The 2018 Notes mature on July 15, 2018 unless repurchased or converted in accordance with their terms prior to such date. We cannot redeem the 2018 Notes prior to maturity. Concurrently, we issued 1.50% convertible senior notes due July 15, 2020 with a principal amount of $250 million . The 2020 Notes are unsecured, unsubordinated obligations, and interest is payable in cash in arrears at a fixed rate of 1.50% on January 15 and July 15 of each year. The 2020 Notes mature on July 15, 2020 unless repurchased or converted in accordance with their terms prior to such date. We cannot redeem the 2020 Notes prior to maturity. In September 2017, we issued 0.25% convertible senior notes due October 1, 2022 with a principal amount of $1.15 billion . The 2022 Notes are unsecured, unsubordinated obligations, and interest is payable in cash in arrears at a fixed rate of 0.25% on April 1 and October 1 of each year. The 2022 Notes mature on October 1, 2022 unless repurchased or converted in accordance with their terms prior to such date. We cannot redeem the 2022 Notes prior to maturity. The terms of the Notes are governed by Indentures by and between us and Wells Fargo Bank, National Association, as Trustee ("the Indentures"). Upon conversion, holders of the Notes will receive cash, shares of Class A common stock or a combination of cash and shares of Class A common stock, at our election. For the 2018 Notes, the initial conversion rate is 12.0075 shares of Class A common stock per $1,000 principal amount, which is equal to an initial conversion price of approximately $83.28 per share of Class A common stock, subject to adjustment. Prior to the close of business on March 14, 2018 , the conversion is subject to the satisfaction of certain conditions as described below. For the 2020 Notes, the initial conversion rate is 12.2340 shares of Class A common stock per $1,000 principal amount, which is equal to an initial conversion price of approximately $81.74 per share of Class A common stock, subject to adjustment. Prior to the close of business on March 13, 2020 , the conversion is subject to the satisfaction of certain conditions, as described below. For the 2022 Notes, the initial conversion rate is 6.7982 shares of Class A common stock per $1,000 principal amount, which is equal to an initial conversion price of approximately $147.10 per share of Class A common stock, subject to adjustment. Prior to the close of business on May 31, 2022, the conversion is subject to the satisfaction of certain conditions, as described below. Holders of the Notes who convert their Notes in connection with certain corporate events that constitute a make-whole fundamental change (as defined in the Indentures) are, under certain circumstances, entitled to an increase in the conversion rate. Additionally, in the event of a corporate event that constitutes a fundamental change (as defined in the Indentures), holders of the Notes may require us to repurchase all or a portion of their Notes at a price equal to 100% of the principal amount of the Notes, plus any accrued and unpaid interest. Holders of the Notes may convert all or a portion of their Notes prior to the close of business on March 14, 2018 for the 2018 Notes, March 13, 2020 for the 2020 Notes, and May 31, 2022 for the 2022 Notes in multiples of $1,000 principal amount, only under the following circumstances: • if the last reported sale price of Class A common stock for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price of the respective Notes on each applicable trading day. This circumstance is effective for the 2022 Notes during any fiscal quarter commencing after the fiscal quarter ending on January 31, 2018; • during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the respective Notes for each day of that five day consecutive trading day period was less than 98% of the product of the last reported sale price of Class A common stock and the conversion rate of the respective Notes on such trading day; or • upon the occurrence of specified corporate events, as noted in the Indentures. In accounting for the issuance of the Notes, we separated each of the Notes into liability and equity components. The carrying amounts of the liability components were calculated by measuring the fair value of similar liabilities that do not have associated convertible features. The carrying amount of the equity components representing the conversion option were determined by deducting the fair value of the liability components from the par value of the respective Notes. These differences represent debt discounts that are amortized to interest expense over the respective terms of the Notes using the effective interest rate method. The equity components are not remeasured as long as they continue to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, we allocated the total amount of issuance costs incurred to liability and equity components based on their relative values. Issuance costs attributable to the liability components are being amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the respective terms of the Notes. The issuance costs attributable to the equity components were netted against the respective equity components in Additional paid-in capital. For the 2018 Notes, we recorded liability issuance costs of $7 million and equity issuance costs of $2 million . Amortization expense for the liability issuance costs was $1 million for both fiscal 2018 and 2017 . For the 2020 Notes, we recorded liability issuance costs of $5 million and equity issuance costs of $2 million . Amortization expense for the liability issuance costs was less than $1 million for both fiscal 2018 and 2017 . For the 2022 Notes, we recorded liability issuance costs of $14 million and equity issuance costs of $4 million . Amortization expense for the liability issuance costs was $1 million for fiscal 2018. The Notes, net consisted of the following (in thousands): January 31, 2018 January 31, 2017 2018 Notes 2020 Notes 2022 Notes 2018 Notes 2020 Notes 2022 Notes Principal amounts: Principal $ 350,000 $ 250,000 $ 1,150,000 $ 350,000 $ 250,000 $ — Unamortized debt discount (7,850 ) (26,968 ) (208,188 ) (24,380 ) (36,820 ) — Unamortized debt issuance costs (641 ) (1,654 ) (13,345 ) (2,050 ) (2,327 ) — Net carrying amount $ 341,509 $ 221,378 $ 928,467 $ 323,570 $ 210,853 $ — Carrying amount of the equity component (1) $ 74,892 $ 66,007 $ 219,702 $ 74,892 $ 66,007 $ — (1) Included on the consolidated balance sheets within Additional paid-in capital, net of $2 million , $2 million , and $4 million for the 2018 Notes, 2020 Notes, and 2022 Notes, respectively, in equity issuance costs. As of January 31, 2018 , the 2018 Notes have a remaining life of approximately 5 months and are classified as current on the consolidated balance sheets. The 2020 Notes and the 2022 Notes have a remaining life of approximately 29 months and 56 months , respectively, and are classified as non-current on the consolidated balance sheets. The effective interest rates of the liability components of the 2018 Notes, 2020 Notes, and 2022 Notes are 5.75% , 6.25% , and 4.60% , respectively. These interest rates were based on the interest rates of similar liabilities at the time of issuance that did not have associated convertible features. The following table sets forth total interest expense recognized related to the Notes (in thousands): Year Ended January 31, 2018 2017 2018 Notes 2020 Notes 2022 Notes 2018 Notes 2020 Notes 2022 Notes Contractual interest expense $ 2,625 $ 3,750 $ 1,086 $ 2,625 $ 3,750 $ — Interest cost related to amortization of debt issuance costs 1,409 673 1,080 1,408 675 — Interest cost related to amortization of the debt discount 16,530 9,852 14,989 15,607 9,257 — We capitalized interest costs related to the Notes of $8 million and $3 million for fiscal 2018 and 2017, respectively. Notes Hedges In connection with the issuance of the Notes, we entered into convertible note hedge transactions with respect to our Class A common stock ("Purchased Options"). The Purchased Options relating to the 2018 Notes give us the option to purchase, subject to anti-dilution adjustments substantially identical to those in the Notes, approximately 4.2 million shares of our Class A common stock for $83.28 per share, exercisable upon conversion of the Notes. The Purchased Options relating to the 2020 Notes give us the option to purchase, subject to anti-dilution adjustments substantially identical to those in the Notes, approximately 3.1 million shares of our Class A common stock for $81.74 per share, exercisable upon conversion of the Notes. The Purchased Options relating to the 2022 Notes give us the option to purchase, subject to anti-dilution adjustments substantially identical to those in the Notes, approximately 7.8 million shares of our Class A common stock for $147.10 per share, exercisable upon conversion of the Notes. The Purchased Options will expire in 2018 for the 2018 Notes, in 2020 for the 2020 Notes, and in 2022 for the 2022 Notes, if not exercised earlier. The Purchased Options are intended to offset potential economic dilution to our Class A common stock upon any conversion of the Notes. The Purchased Options are separate transactions and are not part of the terms of the Notes. We paid an aggregate amount of $144 million for the Purchased Options relating to the 2018 Notes and 2020 Notes, and $176 million for the Purchased Options relating to the 2022 Notes. The amount paid for the Purchased Options is included in Additional paid-in capital on the consolidated balance sheets. Warrants In connection with the issuance of the Notes, we also entered into warrant transactions to sell warrants ("the Warrants") to acquire, subject to anti-dilution adjustments, up to approximately 4.2 million shares over 60 scheduled trading days beginning in October 2018, 3.1 million shares over 60 scheduled trading days beginning in October 2020, and 7.8 million shares over 60 scheduled trading days beginning in January 2023 of our Class A common stock at an exercise price of $107.96 , $107.96 , and $213.96 per share, respectively. If the Warrants are not exercised on their exercise dates, they will expire. If the market value per share of our Class A common stock exceeds the applicable exercise price of the Warrants, the Warrants will have a dilutive effect on our earnings per share assuming that we are profitable. The Warrants are separate transactions, and are not part of the terms of the Notes or the Purchased Options. We received aggregate proceeds of $93 million from the sale of the Warrants related to the 2018 Notes and the 2020 Notes, and $81 million from the sale of the Warrants related to the 2022 Notes. The proceeds from the sale of the Warrants are recorded in Additional paid-in capital on the consolidated balance sheets.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Jan. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Facility and Computing Infrastructure-related Commitments We have entered into non-cancelable agreements for certain of our offices and data centers with various expiration dates. Certain of our office leases are with an affiliate of our Chairman, Mr. Duffield, who is also a significant stockholder (see Note 18). Our operating lease agreements generally provide for rental payments on a graduated basis and for options to renew, which could increase future minimum lease payments if exercised. This includes payments for office and data center square footage, as well as data center power capacity for certain data centers. We generally recognize these expenses on a straight-line basis over the period in which we benefit from the lease and we have accrued for rent expense incurred but not paid. Total rent expense was $82 million , $72 million , and $46 million for fiscal 2018 , 2017 , and 2016 , respectively. In January 2014 , we entered into a 95 -year lease for a 6.9 -acre parcel of vacant land in Pleasanton, California, under which we paid $2 million for base rent from commencement through December 31, 2020. Annual rent payments of $0.2 million plus increases based on increases in the Consumer Price Index begin on January 1, 2021 and continue through the end of the lease. Additionally, we have entered into non-cancelable agreements with computing infrastructure vendors with various expiration dates. As of January 31, 2018 , the future minimum payments by year for our non-cancelable leases and computing infrastructure platforms are as follows (in thousands): Operating Operating Computing Infrastructure Platforms 2019 $ 59,204 $ 11,103 $ 7,461 2020 40,920 12,692 5,500 2021 35,808 12,977 11,000 2022 25,747 13,265 14,000 2023 13,590 13,556 15,250 Thereafter 28,951 20,661 34,250 $ 204,220 $ 84,254 $ 87,461 Legal Matters We are a party to various legal proceedings and claims which arise in the ordinary course of business. We make a provision for a liability relating to legal matters when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed at least quarterly and adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter. In our opinion, as of January 31, 2018 , there was not at least a reasonable possibility that we had incurred a material loss, or a material loss in excess of a recorded accrual, with respect to such loss contingencies.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	12 Months Ended
	Jan. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Common Stock and Stockholders' Equity	Common Stock and Stockholders’ Equity Common Stock As of January 31, 2018 , there were 142 million shares of Class A common stock and 70 million shares of Class B common stock outstanding. The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to 10 votes per share. Each share of Class B common stock can be converted into a share of Class A common stock at any time at the option of the holder. All of our Class A and Class B shares will convert to a single class of common stock upon the date that is the first to occur of (i) October 11, 2032, (ii) such time as the shares of Class B common stock represent less than 9% of the outstanding Class A and Class B common stock, (iii) nine months following the death of both Mr. Duffield and Mr. Bhusri, and (iv) the date on which the holders of a majority of the shares of Class B common stock elect to convert all shares of Class A common stock and Class B common stock into a single class of common stock. Employee Equity Plans Our 2012 Equity Incentive Plan ("EIP") serves as the successor to our 2005 Stock Plan (together with the EIP, the "Stock Plans"). Pursuant to the terms of the EIP, the share reserve increased by 10 million shares in March 2017. As of January 31, 2018 , we had approximately 61 million shares of Class A common stock available for future grants. We also have a 2012 Employee Stock Purchase Plan. Under the ESPP, eligible employees are granted options to purchase shares at the lower of 85% of the fair market value of the stock at the time of grant or 85% of the fair market value at the time of exercise. Options to purchase shares are granted twice yearly on or about June 1 and December 1 and exercisable on or about the succeeding November 30 and May 31, respectively, of each year. Pursuant to the terms of the ESPP, the share reserve increased by 2 million shares in March 2017. As of January 31, 2018 , approximately 7 million shares of Class A common stock were available for issuance under the ESPP. Restricted Stock Units The Stock Plans provide for the issuance of RSUs to employees and non-employees. RSUs generally vest over four years. A summary of information related to RSU activity during fiscal 2018 is as follows: Number of Shares Weighted-Average Balance as of January 31, 2017 11,502,721 $ 78.45 RSUs granted 7,736,434 88.90 RSUs vested (5,412,921 ) 78.26 RSUs forfeited (1,006,718 ) 79.34 Balance as of January 31, 2018 12,819,516 $ 84.77 The weighted-average grant-date fair value of RSUs granted during fiscal 2018 , 2017 , and 2016 was $88.90 , $75.71 , and $85.29 , respectively. The total fair value of RSUs vested as of the vesting dates during fiscal 2018 , 2017 , and 2016 was $528 million , $303 million , and $162 million , respectively. As of January 31, 2018 , there was a total of $957 million in unrecognized compensation cost related to unvested RSUs, which is expected to be recognized over a weighted-average period of approximately 2.7 years. Performance-based Restricted Stock Units During fiscal 2017, 0.3 million shares of PRSUs were granted to all employees other than executive management and included both service conditions and performance conditions related to company-wide goals. These performance conditions were met and the PRSUs vested on March 15, 2017. During fiscal 2018, we recognized $6 million in compensation cost related to these PRSUs. Additionally, during fiscal 2018, 0.4 million shares of PRSUs were granted to all employees other than executive management and included both service conditions and performance conditions related to company-wide goals. These performance conditions were met and the PRSU awards will vest if the individual employee continues to provide service through the vesting date of March 15, 2018. During fiscal 2018, we recognized $31 million in compensation cost related to these PRSUs, and as of January 31, 2018 , there was a total of $7 million in unrecognized compensation cost which is expected to be recognized over a weighted-average period of approximately 2 months. Stock Options The Stock Plans provide for the issuance of incentive and nonstatutory options to employees and non-employees. Options issued under the Stock Plans generally are exercisable for periods not to exceed 10 years and generally vest over five years . A summary of information related to stock option activity during fiscal 2018 is as follows (in millions, except share and per share data): Outstanding Weighted- Aggregate Balance as of January 31, 2017 9,096,592 $ 4.34 $ 716 Stock option grants — — Stock options exercised (2,490,931 ) 4.60 Stock options canceled (10,175 ) 7.76 Balance as of January 31, 2018 6,595,486 $ 4.23 $ 763 Vested and expected to vest as of January 31, 2018 6,595,469 $ 4.23 $ 763 Exercisable as of January 31, 2018 6,594,986 $ 4.23 $ 763 The total grant-date fair value of stock options vested during fiscal 2018 , 2017 , and 2016 was $5 million , $14 million , and $17 million , respectively. The total intrinsic value of the options exercised during fiscal 2018 , 2017 , and 2016 was $234 million , $273 million , and $279 million , respectively. The intrinsic value is the difference between the current fair value of the stock and the exercise price of the stock option. The weighted-average remaining contractual life of vested and expected to vest options as of January 31, 2018 is approximately 3.2 years. As of January 31, 2018 , there was less than $0.1 million in unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of approximately 3 months . The options that are exercisable as of January 31, 2018 have a weighted-average remaining contractual life of approximately 3.2 years. The weighted-average remaining contractual life of outstanding options at January 31, 2018 is approximately 3.2 years. Employee Stock Purchase Plan For fiscal 2018 , 1 million shares of Class A common shares were purchased under the ESPP at a weighted-average price of $69.60 per share, resulting in cash proceeds of $58 million . The fair value of stock purchase rights granted under the ESPP was estimated using the following assumptions: Year Ended January 31, 2018 2017 2016 Expected volatility 25.3% – 32.0% 34.5% – 44.5% 32.0% – 34.2% Expected term (in years) 0.5 0.5 0.5 Risk-free interest rate 1.11% – 1.45% 0.53% – 0.91% 0.26% – 0.51% Dividend yield —% —% —% Weighted-average grant date fair value per share $98.39 – $100.52 $69.00 – $79.30 $67.23 – $71.81

Unearned Revenue and Performanc

Unearned Revenue and Performance Obligations	12 Months Ended
	Jan. 31, 2018
Revenue Recognition and Deferred Revenue [Abstract]
Unearned Revenue and Performance Obligations	Unearned Revenue and Performance Obligations $1.0 billion and $738 million of subscription services revenue was recognized during fiscal 2018 and 2017, respectively, that was included in the unearned revenue balances at the beginning of the respective periods. Professional services revenue recognized in the same periods from unearned revenue balances at the beginning of the respective periods was not material. Transaction Price Allocated to the Remaining Performance Obligations As of January 31, 2018 , approximately $5.2 billion of revenue is expected to be recognized from remaining performance obligations for subscription contracts. We expect to recognize revenue on approximately two thirds of these remaining performance obligations over the next 24 months, with the balance recognized thereafter. Revenue from remaining performance obligations for professional services contracts as of January 31, 2018 was not material.

Other Income (Expense), Net

Other Income (Expense), Net	12 Months Ended
	Jan. 31, 2018
Other Income and Expenses [Abstract]
Other Income (Expense), Net	Other Income (Expense), Net Other income (expense), net consisted of the following (in thousands): Year Ended January 31, 2018 2017 2016 Interest income $ 25,252 $ 11,303 $ 4,855 Interest expense (1) (44,549 ) (30,103 ) (31,932 ) Gain from sale of cost method investment 720 65 3,220 Impairment of cost method investment (692 ) (15,000 ) — Other income (expense) 7,706 1,308 (385 ) Other income (expense), net $ (11,563 ) $ (32,427 ) $ (24,242 ) (1) Interest expense includes the contractual interest expense related to the 2018 Notes, 2020 Notes, and 2022 Notes and non-cash interest expense related to amortization of the debt discount and debt issuance costs, net of capitalized interest costs (see Note 11).

Income Taxes

Income Taxes	12 Months Ended
	Jan. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of loss before provision for (benefit from) income taxes were as follows (in thousands): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Domestic $ (85,167 ) $ (190,043 ) $ (119,302 ) Foreign (229,619 ) (195,470 ) (154,729 ) Total $ (314,786 ) $ (385,513 ) $ (274,031 ) * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2. The provision for (benefit from) income taxes consisted of the following (in thousands): Year Ended January 31, 2018 2017 2016 Current: Federal $ — $ 213 $ (2,012 ) State 177 17 489 Foreign 4,251 3,573 2,869 Total 4,428 3,803 1,346 Deferred: Federal (535 ) (466 ) — State (100 ) (52 ) — Foreign 2,643 (4,099 ) (329 ) Total 2,008 (4,617 ) (329 ) Provision for (benefit from) income taxes $ 6,436 $ (814 ) $ 1,017 The items accounting for the difference between income taxes computed at the federal statutory income tax rate and the provision for (benefit from) income taxes consisted of the following: Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Federal statutory rate 33.8 % 35.0 % 35.0 % Effect of: Foreign income at other than U.S. rates (26.5 )% (18.5 )% (25.7 )% Intercompany transactions 10.2 % 4.2 % 5.2 % Research tax credits 9.1 % 6.4 % 5.1 % State taxes, net of federal benefit — % — % (0.2 )% U.S. corporate tax rate reduction (81.3 )% — % — % Changes in valuation allowance 33.0 % (20.4 )% (15.1 )% Stock compensation 20.0 % (6.1 )% (5.4 )% Other (0.4 )% (0.4 )% 0.7 % (2.1 )% 0.2 % (0.4 )% * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2. On December 22, 2017, the Tax Act was enacted into law and reduced the corporate income tax rate to 21% effective January 1, 2018. Accordingly, we adjusted our federal statutory rate to a blended rate of 33.8% for the fiscal year ended January 31, 2018. As a result of the Tax Act, and the reduction in the corporate income tax rate, the U.S. federal and state deferred tax assets were remeasured resulting in a $256 million reduction of net deferred tax assets which was offset by changes in our valuation allowance. The Tax Act includes a number of other provisions including the elimination of loss carrybacks and limitations on the use of future losses. The Tax Act imposes a one-time mandatory transition tax on accumulated foreign earnings and as of the measurement date of November 2, 2017, our foreign operations did not have accumulated income and, therefore, the transition tax did not apply. The Tax Act requires complex computations to be performed that were not previously required in U.S. tax law, judgments to be made in interpretation of the provisions of the Tax Act, estimates in calculations, and the preparation and analysis of information not previously relevant or regularly produced. The U.S. Treasury Department, the Internal Revenue Service ("IRS"), and other standard-setting bodies could interpret or issue guidance on how provisions of the Tax Act will be applied or otherwise administered that is different from our current interpretation. The Company has calculated its best estimate of the impact of the Tax Act in its year end income tax provision in accordance with its understanding of the Tax Act and guidance available as of the date of this filing. As we complete our analysis of the Tax Act, collect and prepare necessary data, and interpret any additional guidance, we may make adjustments to our initial assessment. Pursuant to Staff Accounting Bulletin No. 118, adjustments to the provisional amounts recorded by the Company as of January 31, 2018 that are identified within a subsequent measurement period of up to one year from the enactment date will be included as an adjustment to tax expense from continuing operations in the period the amounts are determined. As a result of our history of net operating losses, the current provision for income taxes relates to state income taxes and the current foreign provision from our profitable foreign entities. Significant components of our deferred tax assets and liabilities were as follows (in thousands): January 31, 2018 2017 *As Adjusted Deferred tax assets: Unearned revenue $ 27,934 $ 40,810 Other reserves and accruals 14,945 23,134 Federal net operating loss carryforwards 422,235 110,974 State and foreign net operating loss carryforwards 81,757 25,783 Property and equipment — 24,754 Share-based compensation 39,294 70,642 Research and development credits 110,694 78,283 Other 5,622 23,209 702,481 397,589 Valuation allowance (625,030 ) (292,365 ) Deferred tax assets, net of valuation allowance 77,451 105,224 Deferred tax liabilities: Intangibles (1,453 ) (3,742 ) Intercompany transactions (40,338 ) (62,800 ) Other prepaid assets (742 ) (1,079 ) Deferred commissions (29,231 ) (33,267 ) Property and equipment (3,803 ) — (75,567 ) (100,888 ) Net deferred tax assets $ 1,884 $ 4,336 * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2. We adopted ASU No. 2016-09 effective February 1, 2017, and recorded $448 million of U.S deferred tax assets related to excess tax benefits from share-based award activity as of January 31, 2017, which was fully offset by an increase in the valuation allowance. We regularly assess the need for a valuation allowance against our deferred tax assets by considering both positive and negative evidence related to whether it is more likely than not that our deferred tax assets will be realized. In evaluating the need for a valuation allowance, we consider the cumulative losses in recent years as a significant piece of negative evidence that is generally difficult to overcome. As of January 31, 2018, we continue to maintain a full valuation allowance against our U.S. federal and state deferred tax assets. As of January 31, 2018, we recorded a valuation allowance of $625 million for the portion of the deferred tax asset that we do not expect to be realized. The valuation allowance on our net deferred tax assets increased by $333 million and $100 million in fiscal 2018 and 2017, respectively. The increase in the valuation allowance is mainly due to an increase in our deferred tax assets on our net operating losses as a result of the recognition of excess tax benefits from share-based compensation resulting from the adoption of ASU No. 2016-09. This was partially offset by a decrease in our federal deferred tax assets resulting from the re-measurement of the corporate tax rate from 35% to 21%. We will continue to reassess the future realization of the deferred tax assets and adjust the valuation allowance accordingly. As of January 31, 2018, we had approximately $2.0 billion of federal, $1.3 billion of state and $25 million of foreign net operating loss carryforwards available to offset future taxable income. If not utilized, the federal and state net operating loss carryforwards expire in varying amounts between fiscal 2019 and 2038. The foreign net operating losses do not expire and may be carried forward indefinitely. We also had approximately $83 million of federal and $87 million of California research and development tax credit carryforwards as of January 31, 2018. The federal credits expire in varying amounts between fiscal 2026 and 2038. The California research credits do not expire and may be carried forward indefinitely. Our ability to utilize the net operating loss and tax credit carryforwards in the future may be subject to substantial restrictions in the event of past or future ownership changes as defined in Section 382 of the Internal Revenue Code of 1986, as amended, and similar state tax law. A reconciliation of the gross unrecognized tax benefit is as follows (in thousands): Year Ended January 31, 2018 2017 2016 Unrecognized tax benefits at the beginning of the period $ 116,801 $ 98,460 $ 88,663 Additions for tax positions taken in prior years 1,500 3,981 2,818 Reductions for tax positions taken in prior years (8,121 ) — (881 ) Decrease for tax positions taken in prior years due to federal rate reduction (10,062 ) — — Additions for tax positions related to the current year 7,731 14,475 9,144 Reductions related to a lapse of applicable statute of limitations — (115 ) (1,284 ) Unrecognized tax benefits at the end of the period $ 107,849 $ 116,801 $ 98,460 Our policy is to include interest and penalties related to unrecognized tax benefits within our provision for income taxes. Of the total amount of unrecognized tax benefits of $108 million , $1 million , if recognized, would impact the effective tax rate, as of January 31, 2018. The reduction for tax positions taken in prior years is mainly due to the re-measurement of certain U.S. uncertain tax benefits from 35% to 21% under the Tax Act. We do not expect the total amounts of unrecognized tax benefits will significantly increase or decrease within 12 months of the reporting date. We file federal, state, and foreign income tax returns in jurisdictions with varying statutes of limitations. Due to our net operating loss carryforwards, our income tax returns generally remain subject to examination by federal and most state and foreign tax authorities. On December 1, 2015, the United States Tax Court issued its final decision with respect to Altera Corporation’s litigation with the IRS. The litigation relates to the treatment of share-based compensation expense in an inter-company cost-sharing arrangement with the taxpayer’s foreign subsidiary for fiscal 2004 through 2007. In its final decision, the Court accepted Altera’s position of excluding share-based compensation in its cost sharing arrangement and concluded that the related IRS Regulations were invalid. Subsequent to the decision, the IRS filed its appeal on February 23, 2016. Although the IRS has appealed the decision, based on the facts and circumstances of the Tax Court Case, we believe that it is more likely than not that the decision will be upheld. We have therefore recorded the effects of the decision and determined that there was no material impact to our effective tax rate and income tax expense due to our current full valuation allowance position. We will continue to monitor ongoing developments and potential impacts to our consolidated financial statements.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Jan. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including our outstanding stock options, outstanding warrants, common stock related to unvested early exercised stock options, common stock related to unvested restricted stock units and awards and convertible senior notes to the extent dilutive, and common stock issuable pursuant to the ESPP. Basic and diluted net loss per share was the same for each period presented, as the inclusion of all potential common shares outstanding would have been anti-dilutive. The net loss per share attributable to common stockholders is allocated based on the contractual participation rights of the Class A common shares and Class B common shares as if the loss for the year has been distributed. As the liquidation and dividend rights are identical, the net loss attributable to common stockholders is allocated on a proportionate basis. The following table presents the calculation of basic and diluted net loss attributable to common stockholders per share (in thousands, except per share data): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Class A Class B Class A Class B Class A Class B Basic and diluted net loss attributable to Class A and Class B common stockholders per share: Numerator: Allocation of distributed net loss attributable to common stockholders $ (208,159 ) $ (113,063 ) $ (236,946 ) $ (147,753 ) $ (160,173 ) $ (114,875 ) Denominator: Weighted-average common shares outstanding 134,642 73,132 122,085 76,129 110,655 79,361 Basic and diluted net loss per share $ (1.55 ) $ (1.55 ) $ (1.94 ) $ (1.94 ) $ (1.45 ) $ (1.45 ) * See Note 2 for a summary of adjustments. The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share were as follows (in thousands): Year Ended January 31, 2018 2017 2016 Outstanding common stock options 6,595 9,097 12,863 Shares subject to repurchase — 110 621 Unvested restricted stock awards, units, and PRSUs 13,209 12,155 9,851 Shares related to the convertible senior notes 15,079 7,261 7,261 Shares subject to warrants related to the issuance of convertible senior notes 15,079 7,261 7,261 Shares issuable pursuant to the ESPP 466 485 345 50,428 36,369 38,202

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Jan. 31, 2018
Related Party Transactions [Abstract]
Related-Party Transactions	Related Party Transactions We currently lease certain office space from an affiliate of our Chairman, Mr. Duffield, adjacent to our corporate headquarters in Pleasanton, California under various lease agreements. The average term of the agreements is nine years and the total rent expense under these agreements was $8 million , $8 million , and $6 million for fiscal 2018 , 2017 , and 2016 , respectively.

Geographic Information

Geographic Information	12 Months Ended
	Jan. 31, 2018
Segment Reporting [Abstract]
Geographic Information	Geographic Information Disaggregation of Revenue We sell our subscription contracts and related services in two primary geographical markets: to customers located in the United States, and to customers located outside of the United States. Revenue by geography is generally based on the address of the customer as specified in our master subscription agreement. The following table sets forth revenue by geographic area (in thousands): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ 1,694,347 $ 1,283,475 $ 966,250 Other countries 448,703 290,965 190,440 Total $ 2,143,050 $ 1,574,440 $ 1,156,690 * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2. Long-Lived Assets We attribute our long-lived assets, which primarily consist of property and equipment, to a country based on the physical location of the assets. The following table sets forth property and equipment by geographic area (in thousands): January 31, 2018 2017 United States $ 479,996 $ 321,442 Ireland 52,904 35,720 Other countries 13,709 8,715 Total $ 546,609 $ 365,877

401(k) Plan

401(k) Plan	12 Months Ended
	Jan. 31, 2018
Retirement Benefits [Abstract]
401(k) Plan	401(k) Plan We have a qualified defined contribution plan under Section 401(k) of the Internal Revenue Code covering eligible employees. In fiscal 2017, we began to match a certain portion of employee contributions up to a fixed maximum per employee. Our contributions to the plan were $15 million in fiscal 2018 and $6 million in fiscal 2017 .

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Jan. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	Selected Quarterly Financial Data (unaudited) The following tables set forth selected unaudited quarterly consolidated statements of operations data for each of the eight quarters in fiscal 2018 and 2017 (in thousands except per share data): Quarter ended January 31, 2018 October 31, 2017 July 31, 2017 April 30, 2017 January 31, 2017 October 31, 2016 July 31, 2016 April 30, 2016 *As Adjusted *As Adjusted *As Adjusted *As Adjusted Consolidated Statements of Operations Data: Total revenues $ 582,480 $ 555,389 $ 525,320 $ 479,861 $ 439,584 $ 413,522 $ 373,657 $ 347,677 Operating loss (81,335 ) (80,059 ) (81,629 ) (60,200 ) (88,939 ) (105,932 ) (86,685 ) (71,530 ) Net loss (89,100 ) (85,546 ) (82,532 ) (64,044 ) (88,269 ) (110,114 ) (107,813 ) (78,503 ) Net loss per share, basic and diluted (0.42 ) (0.41 ) (0.40 ) (0.31 ) (0.44 ) (0.55 ) (0.55 ) (0.40 ) * See Note 2 for a summary of adjustments.

Accounting Standards and Signif

Accounting Standards and Significant Accounting Policies (Policies)	12 Months Ended
	Jan. 31, 2018
Accounting Policies [Abstract]
Fiscal Year	Fiscal Year Our fiscal year ends on January 31. References to fiscal 2018 , for example, refer to the year ended January 31, 2018 .
Basis of Presentation	Basis of Presentation These consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP"). The consolidated financial statements include the results of Workday, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. Effective February 1, 2017, we adopted the requirements of Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers and ASU No. 2016-18, Statement of Cash Flows, Restricted Cash as discussed in Note 2. All amounts and disclosures set forth in this Form 10-K have been updated to comply with the new standards, as indicated by the "as adjusted" footnote. Certain prior period amounts reported in our consolidated financial statements and notes thereto have been reclassified to conform to current period presentation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenues and expenses during the reporting period. These estimates include, but are not limited to, the determination of the period of benefit for deferred commissions, certain assumptions used in the valuation of equity awards, and the fair value of assets acquired and liabilities assumed through business combinations. Actual results could differ from those estimates and such differences could be material to our consolidated financial position and results of operations.
Segment Information	Segment Information We operate in one operating segment, cloud applications. Operating segments are defined as components of an enterprise where separate financial information is evaluated regularly by the chief operating decision maker, who is our chief executive officer, in deciding how to allocate resources and assessing performance. Our chief operating decision maker allocates resources and assesses performance based upon discrete financial information at the consolidated level.
Revenue Recognition	Revenue Recognition We derive our revenues primarily from subscription services and professional services. Revenues are recognized when control of these services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services. We determine revenue recognition through the following steps: • 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 Subscription Services Revenues Subscription services revenues primarily consist of fees that provide customers access to one or more of our cloud applications for finance, human resources, and analytics, with routine customer support. Revenue is generally recognized on a ratable basis over the contract term beginning on the date that our service is made available to the customer. Our subscription contracts are generally three years or longer in length, billed annually in advance, and non-cancelable. Professional Services Revenues Professional services revenues primarily consist of fees for deployment and optimization services, as well as training. The majority of our consulting contracts are billed on a time and materials basis and revenue is recognized over time as the services are performed. For contracts billed on a fixed price basis, revenue is recognized over time based on the proportion performed. Contracts with Multiple Performance Obligations Some of our contracts with customers contain multiple performance obligations. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to the separate performance obligations on a relative standalone selling price basis. We determine the standalone selling prices based on our overall pricing objectives, taking into consideration market conditions and other factors, including the value of our contracts, the cloud applications sold, customer demographics, geographic locations, and the number and types of users within our contracts.
Fair Value Measurement	Fair Value Measurement We measure our cash equivalents, marketable securities and foreign currency derivative contracts at fair value at each reporting period using a fair value hierarchy that requires that we 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 that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2 — Other inputs that are directly or indirectly observable in the marketplace. Level 3 — Unobservable inputs that are supported by little or no market activity.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with maturities of three months or less at the time of purchase. Our cash equivalents primarily consist of investments in U.S. agency obligations, U.S. treasury securities, corporate bonds, commercial paper, and money market funds.
Marketable Securities	Marketable Securities Our marketable securities primarily consist of investments in U.S. agency obligations, U.S. treasury securities, corporate bonds, and commercial paper. We classify our marketable securities as available-for-sale at the time of purchase and reevaluate such classification as of each balance sheet date. We consider all marketable securities as available for use in current operations, including those with maturity dates beyond one year, and therefore classify these securities as current assets in the accompanying consolidated balance sheets. All marketable securities are recorded at their estimated fair value. Unrealized gains and losses on available-for-sale securities are recorded in Accumulated other comprehensive income (loss) ("OCI"). We evaluate our investments to assess whether those in 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 and declines in value judged to be other-than-temporary are determined based on the specific identification method and are reported in Other income (expense), net on the consolidated statements of operations. If quoted prices for identical instruments are available in an active market, marketable securities are classified within Level 1 of the fair value hierarchy. If quoted prices for identical instruments in active markets are not available, fair values are estimated using quoted prices of similar instruments and are classified within Level 2 of the fair value hierarchy. To date, all of our marketable securities can be valued using one of these two methodologies.
Trade and Other Receivables	Trade and Other Receivables Trade and other receivables are primarily comprised of trade receivables that are recorded at the invoice amount, net of an allowance for doubtful accounts, which is not material. Other receivables represent unbilled receivables related to subscription and professional services contracts.
Deferred Commissions	Deferred Commissions Sales commissions earned by our sales force are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions for initial contracts are deferred and then amortized on a straight-line basis over a period of benefit that we have determined to be five years. We determined the period of benefit by taking into consideration our customer contracts, our technology and other factors. Sales commissions for renewal contracts are deferred and then amortized on a straight-line basis over the related contractual renewal period. Amortization expense is included in Sales and marketing expenses on the consolidated statements of operations.
Derivative Financial Instruments and Hedging Activities	Derivative Financial Instruments and Hedging Activities We use derivative financial instruments to manage foreign currency risks. Derivative instruments are carried at fair value and recorded as either an asset or liability on the consolidated balance sheets. Gains and losses resulting from changes in fair value are accounted for depending on the use of the derivative and whether it is designated and qualifies for hedge accounting. For foreign currency forward contracts not designated as hedging instruments, which we use to hedge a portion of our net outstanding monetary assets and liabilities, the gains or losses are recorded in Other income (expense), net on the consolidated statements of operations in the period of change. For a derivative instrument designated as a cash flow hedge, which we use to hedge certain customer contracts denominated in foreign currencies, the change in fair value on the effective portion is recorded to OCI on our consolidated balance sheets each reporting period. The balance in OCI is subsequently reclassified to the related revenue line item on the consolidated statements of operations in the same period that the underlying revenues are earned. Our foreign currency contracts are classified within Level 2 of the fair value hierarchy because the valuation inputs are based on quoted prices and market observable data of similar instruments in active markets, such as currency spot and forward rates.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation is recorded using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the shorter of the estimated useful lives of the assets or the related lease term. Property and equipment is reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable.
Business Combinations	Business Combinations We use our best estimates and assumptions to assign fair value to the tangible and intangible assets acquired and liabilities assumed as of the acquisition date. Our estimates are inherently uncertain and subject to refinement. During the measurement period, which may be up to one year from the acquisition date, we may record adjustments to the fair value of these tangible and intangible assets acquired and liabilities assumed, with the corresponding offset to goodwill. In addition, uncertain tax positions and tax-related valuation allowances are initially established in connection with a business combination as of the acquisition date. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to our consolidated statements of operations.
Goodwill and Acquisition-Related Intangible Assets	Goodwill and Acquisition-Related Intangible Assets Acquisition-related intangible assets with finite lives are typically amortized over useful lives of three to four years. Goodwill amounts are not amortized. Acquisition-related intangible assets and goodwill are tested for impairment at least annually, and more frequently upon the occurrence of certain events.
Unearned Revenue	Unearned Revenue Unearned revenue primarily consists of customer billings in advance of revenues being recognized from our subscription contracts. We generally invoice our customers annually in advance for our subscription services. Our typical payment terms provide that customers pay a portion of the total arrangement fee within 30 days of the contract date. Unearned revenue that is anticipated to be recognized during the succeeding twelve -month period is recorded as current unearned revenue and the remaining portion is recorded as noncurrent.
Convertible Senior Notes	Convertible Senior Notes In June 2013, we issued 0.75% convertible senior notes due July 15, 2018 ("2018 Notes") with a principal amount of $350 million . Concurrently, we issued 1.50% convertible senior notes due July 15, 2020 ("2020 Notes") with a principal amount of $250 million . In September 2017, we issued 0.25% convertible senior notes due October 1, 2022 ("2022 Notes") with a principal amount of $1.15 billion (together with the 2018 Notes and 2020 Notes, referred to as "the Notes"). In accounting for the issuance of the Notes, we separated each of the Notes into liability and equity components. The carrying amounts of the liability components were calculated by measuring the fair value of similar liabilities that do not have associated convertible features. The carrying amount of the equity components representing the conversion option were determined by deducting the fair value of the liability components from the par value of the respective Notes. These differences represent debt discounts that are amortized to interest expense over the respective terms of the Notes using the effective interest rate method. The equity components are not remeasured as long as they continue to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, we allocated the total amount of issuance costs incurred to liability and equity components based on their relative values. Issuance costs attributable to the liability components are being amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the respective terms of the Notes. The issuance costs attributable to the equity components were netted against the respective equity components in Additional paid-in capital.
Advertising Expenses	Advertising Expenses Advertising is expensed as incurred.
Share-Based Compensation	Share-Based Compensation We measure and recognize compensation expense for share-based awards issued to employees and non-employees, including restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs"), and purchases under the 2012 Employee Stock Purchase Plan ("ESPP"), on our consolidated statements of operations. For RSUs and PRSUs, fair value is based on the closing price of our common stock on the grant date. Compensation expense, net of estimated forfeitures, is recognized on a straight-line basis over the requisite service period. Non-employee RSUs subject to vesting are required to be periodically revalued over the requisite service period. The requisite service period of the awards is generally the same as the vesting period. For shares issued under the ESPP, fair value is estimated using the Black-Scholes option-pricing model. Compensation expense is recognized on a straight-line basis over the offering period. We determine the assumptions for the option-pricing model as follows: • Risk-Free Interest Rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date closest to the grant date for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the ESPP purchase rights. • Expected Term. The expected term represents the period that our ESPP is expected to be outstanding. The expected term for the ESPP approximates the offering period. • Volatility. The volatility is based on a blend of historical volatility and implied volatility of our common stock. Implied volatility is based on market traded options of our common stock. • Dividend Yield. The dividend yield is assumed to be zero as we have not paid and do not expect to pay dividends.
Income Taxes	Income Taxes We record a provision for income taxes for the anticipated tax consequences of the reported results of operations using the asset and liability method. Under this method, we recognize deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. We record a valuation allowance to reduce our deferred tax assets to the net amount that we believe is more likely than not to be realized. We recognize tax benefits from uncertain tax positions only if we believe that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Although we believe that we have adequately reserved for our uncertain tax positions, we can provide no assurance that the final tax outcome of these matters will not be materially different. We make adjustments to these reserves when facts and circumstances change, such as the closing of a tax audit or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on our financial condition and operating results. The provision for income taxes includes the effects of any accruals that we believe are appropriate, as well as the related net interest and penalties.
Warranties and Indemnification	Warranties and Indemnification Our cloud applications are generally warranted to perform materially in accordance with our online documentation under normal use and circumstances. Additionally, our contracts generally include provisions for indemnifying customers against liabilities if use of our cloud applications infringe a third party’s intellectual property rights. We may also incur liabilities if we breach the security, privacy and/or confidentiality obligations in our contracts. To date, we have not incurred any material costs, and we have not accrued any liabilities in the accompanying consolidated financial statements, as a result of these obligations. We have entered into service-level agreements with a majority of our customers committing to defined levels of service availability and performance and permitting those customers to receive credits or refunds for prepaid amounts related to unused subscription services or to terminate their agreements in the event that we fail to meet those levels. To date, we have not experienced any significant failures to meet defined levels of availability and performance of those agreements and, as a result, we have not accrued any liabilities related to these agreements on the consolidated financial statements.
Foreign Currency Exchange	Foreign Currency Exchange The functional currency for certain of our foreign subsidiaries is the U.S. dollar, while others use local currencies. We translate the foreign functional currency financial statements to U.S dollars for those entities that do not have U.S. dollars as their functional currency using the exchange rates at the balance sheet date for assets and liabilities, the period average exchange rates for revenues and expenses, and the historical exchange rates for equity transactions. The effects of foreign currency translation adjustments are recorded in OCI as a component of stockholders' equity, and related periodic movements are summarized as a line item in our consolidated statements of comprehensive loss. Foreign currency transaction gains and losses are included in Other income (expense), net on the consolidated statements of operations.
Concentrations of Risk and Significant Customers	Concentrations of Risk and Significant Customers Our financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents, marketable securities, and trade and other receivables. Our deposits exceed federally insured limits. No single customer represented over 10% of trade and other receivables on the consolidated financial statements as of January 31, 2018 or 2017 . No single customer represented over 10% of total revenues for any of the periods on the consolidated financial statements. In order to reduce the risk of down-time of our cloud applications, we have established data centers in various geographic regions. We have internal procedures to restore services in the event of disaster at one of our current data center facilities. We serve our customers and users from data center facilities operated by third parties, located in Ashburn, Virginia; Atlanta, Georgia; Portland, Oregon; Dublin, Ireland; Amsterdam, the Netherlands; and Toronto, Canada. Even with these procedures for disaster recovery in place, our cloud applications could be significantly interrupted during the implementation of the procedures to restore services. In addition, we rely upon third-party hosted infrastructure partners, including Amazon Web Services ("AWS"), to serve customers and operate certain aspects of our services, such as environments for development testing, training and sales demonstrations, as well as others. Given this, any disruption of or interference at our hosted infrastructure partners would impact our operations and our business could be adversely impacted.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10) , which requires entities to carry all investments in equity securities at fair value and recognize any changes in fair value in net income. Under the standard, equity investments that do not have readily determinable fair values and do not qualify for the net asset value practical expedient are eligible for the measurement alternative. For our equity investments in private companies, we will elect the measurement alternative, defined as cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. The guidance is effective for our fiscal year beginning February 1, 2018 on a prospective basis for the amendments related to equity securities without readily determinable fair values existing as of the date of adoption. We plan to adopt the new standard in the first quarter of fiscal 2019 and do not expect it to have a material impact on our consolidated financial statements. The impact of the new standard going forward could result in volatility in Other income (expense), net on the consolidated statements of operations in future periods due to the valuation and timing of identical or similar investments of the same issuer. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which requires the recognition of lease assets and lease liabilities on the balance sheet by lessees for those leases currently classified as operating leases under ASC Topic 840 Leases. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020. We continue to evaluate the effect of adopting this guidance on our consolidated financial statements and related disclosures and we expect our operating leases, as disclosed in Note 12, will be subject to the new standard. Upon adoption, we will recognize right-of-use assets and operating lease liabilities on our consolidated balance sheets, which will increase our total assets and total liabilities. We are evaluating the accounting, transition, and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory (Topic 740) , which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Prior to the issuance of this ASU, existing guidance prohibited the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset had been sold to an outside party. The guidance is effective for our fiscal year beginning February 1, 2018. We plan to adopt the new standard in the first quarter of fiscal 2019 and do not expect it to have a material impact on our consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815) , to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020. We are evaluating the accounting, transition, and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption. 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, which provides entities the option to reclassify tax effects stranded in accumulated other comprehensive income as a result of the 2017 Tax Cuts and Jobs Act ("the Tax Act") to retained earnings. The guidance is effective for our fiscal year beginning February 1, 2019. Early adoption is permitted. We plan to adopt the new standard in the first quarter of fiscal 2020 and do not expect it to have a material impact on our consolidated financial statements. Recently Adopted Accounting Pronouncements ASU No. 2014-09 In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, Revenue from Contracts with Customers ("Topic 606"). Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition ("Topic 605") , and requires the recognition of revenue when promised goods or services are transferred to customers in an amount that reflects the considerations to which the entity expects to be entitled to in exchange for those goods or services. Topic 606 also includes Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers , which requires the deferral of incremental costs of obtaining a contract with a customer. Collectively, we refer to Topic 606 and Subtopic 340-40 as the "new standard." We early adopted the requirements of the new standard as of February 1, 2017, utilizing the full retrospective method of transition. Adoption of the new standard resulted in changes to our accounting policies for revenue recognition, trade and other receivables, and deferred commissions. We applied the new standard using a practical expedient where the consideration allocated to the remaining performance obligations or an explanation of when we expect to recognize that amount as revenue for all reporting periods presented before the date of the initial application is not disclosed. The impact of adopting the new standard on our fiscal 2017 and fiscal 2016 revenues was not material. The primary impact of adopting the new standard relates to the deferral of incremental commission costs of obtaining subscription contracts. Under Topic 605, we deferred only direct and incremental commission costs to obtain a contract and amortized those costs on a straight-line basis over the term of the related subscription contract, which was generally three years or longer. Under the new standard, we defer all incremental commission costs to obtain the contract. We amortize these costs on a straight-line basis over a period of benefit that we have determined to be five years or the related contractual renewal period, depending on whether the contract is an initial or renewal contract, respectively. ASU No. 2016-09 In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718), which simplifies the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and classification in the statement of cash flows. As of February 1, 2017, we adopted the applicable provisions of ASU No. 2016-09 as follows: • The guidance requires excess tax benefits and tax deficiencies to be recorded as income tax benefit or expense in the statement of operations when the awards vest or are settled, and eliminates the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the statement of cash flows. We adopted the guidance prospectively effective February 1, 2017. Amounts previously recorded to Additional paid -in capital related to windfall tax benefits prior to February 1, 2017 remain in Stockholders' equity. • The guidance eliminates the requirement that excess tax benefits must be realized (through a reduction in income taxes payable) before companies can recognize them. We have applied the modified retrospective transition method upon adoption. The previously unrecognized excess tax effects were recorded as a deferred tax asset in the amount of $448.0 million , of which $447.8 million was fully offset by a valuation allowance, and the remaining $0.2 million resulted in a cumulative-effect adjustment to Accumulated deficit as of February 1, 2017. ASU No. 2016-18 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) , which requires that a statement of cash flows explain the change during the period for the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. We early adopted ASU No. 2016-18 retrospectively, effective February 1, 2017. As a result of including restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the consolidated statements of cash flows, net cash flows for fiscal 2017 increased by $2 million .

Accounting Standards and Sign33

Accounting Standards and Significant Accounting Policies (Tables)	12 Months Ended
	Jan. 31, 2018
Accounting Policies [Abstract]
Schedule of Recently Adopted Accounting Pronouncements	We adjusted our consolidated financial statements from amounts previously reported due to the adoption of ASU No. 2014-09 and ASU No. 2016-18. Select consolidated balance sheet line items, which reflect the adoption of the new ASU's are as follows (in thousands): January 31, 2017 As Previously Reported Adjustments As Adjusted Assets Trade and other receivables, net $ 383,908 $ 25,872 a $ 409,780 Prepaid expenses and other current assets 88,336 (21,746 ) a 66,590 Deferred costs 27,537 23,793 a 51,330 Deferred costs, noncurrent 43,310 73,939 a 117,249 Liabilities Unearned revenue $ 1,097,417 $ (11,205 ) a $ 1,086,212 Unearned revenue, noncurrent 135,970 (639 ) a 135,331 Select audited consolidated statement of operations line items, which reflect the adoption of the new ASUs are as follows (in thousands, except per share data): Year ended January 31, 2017 As Previously Reported Adjustments As Adjusted Revenues: Subscription services $ 1,287,104 $ 3,629 a $ 1,290,733 Professional services 282,303 1,404 a 283,707 Total revenues 1,569,407 5,033 a 1,574,440 Costs and expenses: Sales and marketing 583,874 (18,546 ) a 565,328 Operating loss (376,665 ) 23,579 a (353,086 ) Net loss $ (408,278 ) $ 23,579 a $ (384,699 ) Net loss per share, basic and diluted $ (2.06 ) $ 0.12 a $ (1.94 ) Year ended January 31, 2016 As Previously Reported Adjustments As Adjusted Revenues: Subscription services $ 929,234 $ (9,038 ) a $ 920,196 Professional services 233,112 3,382 a 236,494 Total revenues 1,162,346 (5,656 ) a 1,156,690 Costs and expenses: Sales and marketing 434,056 (20,526 ) a 413,530 Operating loss (264,659 ) 14,870 a (249,789 ) Net loss $ (289,918 ) $ 14,870 a $ (275,048 ) Net loss per share, basic and diluted $ (1.53 ) $ 0.08 a $ (1.45 ) Select audited consolidated statement of cash flows line items, which reflect the adoption of the new ASUs are as follows (in thousands): Year ended January 31, 2017 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (408,278 ) $ 23,579 a $ (384,699 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Amortization of deferred costs 25,577 19,768 a 45,345 Changes in operating assets and liabilities: Trade and other receivables, net (88,639 ) (3,116 ) a (91,755 ) Deferred costs (44,533 ) (38,315 ) a (82,848 ) Prepaid expenses and other assets (20,847 ) 4,053 a, b (16,794 ) Unearned revenue 327,615 (3,998 ) a 323,617 Net cash provided by (used in) operating activities 348,655 1,971 b 350,626 Net increase (decrease) in cash, cash equivalents, and restricted cash 239,836 1,971 b 241,807 Cash, cash equivalents, and restricted cash at the end of period $ 539,923 $ 1,971 b $ 541,894 Year ended January 31, 2016 As Previously Reported Adjustments As Adjusted Cash flows from operating activities Net loss $ (289,918 ) $ 14,870 a $ (275,048 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Amortization of deferred costs 23,477 12,539 a 36,016 Changes in operating assets and liabilities: Trade and other receivables, net (105,264 ) (10,512 ) a (115,776 ) Deferred costs (33,899 ) (33,065 ) a (66,964 ) Prepaid expenses and other assets (28,366 ) 8,245 a (20,121 ) Unearned revenue 266,805 7,923 a 274,728 Net cash provided by (used in) operating activities 258,637 — b 258,637 a Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. b Adjusted to reflect the adoption of ASU No. 2016-18, Statement of Cash Flows, Restricted Cash.

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Jan. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Marketable Securities	At January 31, 2018 , marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Aggregate Fair Value U.S. agency obligations $ 683,551 $ — $ (1,127 ) $ 682,424 U.S. treasury securities 797,977 — (1,142 ) 796,835 Corporate bonds 470,259 16 (1,154 ) 469,121 Commercial paper 602,727 — — 602,727 Money market funds 551,804 — — 551,804 $ 3,106,318 $ 16 $ (3,423 ) $ 3,102,911 Included in cash and cash equivalents $ 969,417 $ — $ (1 ) $ 969,416 Included in marketable securities $ 2,136,901 $ 16 $ (3,422 ) $ 2,133,495 At January 31, 2017 , marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Aggregate Fair Value U.S. agency obligations $ 908,874 $ 179 $ (535 ) $ 908,518 U.S. treasury securities 192,028 48 (25 ) 192,051 Corporate bonds 290,272 42 (429 ) 289,885 Commercial paper 323,106 — — 323,106 Money market funds 24,425 — — 24,425 $ 1,738,705 $ 269 $ (989 ) $ 1,737,985 Included in cash and cash equivalents $ 281,163 $ — $ — $ 281,163 Included in marketable securities $ 1,457,542 $ 269 $ (989 ) $ 1,456,822

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Jan. 31, 2018
Fair Value Disclosures [Abstract]
Information about Assets and Liabilities that are Measured at Fair Value on a Recurring Basis	The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis and their assigned levels within the valuation hierarchy as of January 31, 2018 (in thousands): Description Level 1 Level 2 Level 3 Total U.S. agency obligations $ — $ 682,424 $ — $ 682,424 U.S. treasury securities 796,835 — — 796,835 Corporate bonds — 469,121 — 469,121 Commercial paper — 602,727 — 602,727 Money market funds 551,804 — — 551,804 Foreign currency derivative assets — 98 — 98 Total assets $ 1,348,639 $ 1,754,370 $ — $ 3,103,009 Foreign currency derivative liabilities $ — $ 32,912 $ — $ 32,912 Total liabilities $ — $ 32,912 $ — $ 32,912 The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis and their assigned levels within the valuation hierarchy as of January 31, 2017 (in thousands): Description Level 1 Level 2 Level 3 Total U.S. agency obligations $ — $ 908,518 $ — $ 908,518 U.S. treasury securities 192,051 — — 192,051 Corporate bonds — 289,885 — 289,885 Commercial paper — 323,106 — 323,106 Money market funds 24,425 — — 24,425 Foreign currency derivative assets — 7,909 — 7,909 Total assets $ 216,476 $ 1,529,418 $ — $ 1,745,894 Foreign currency derivative liabilities $ — $ 2,127 $ — $ 2,127 Total liabilities $ — $ 2,127 $ — $ 2,127
Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments	The following table presents the carrying amounts and estimated fair values of our financial instruments that are not recorded at fair value on the consolidated balance sheets (in thousands): January 31, 2018 January 31, 2017 Net Carrying Amount Estimated Net Carrying Amount Estimated 0.75% Convertible senior notes $ 341,509 $ 504,994 $ 323,570 $ 402,259 1.50% Convertible senior notes 221,378 385,550 210,853 310,470 0.25% Convertible senior notes 928,467 1,200,577 — —

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Jan. 31, 2018
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment, net consisted of the following (in thousands): January 31, 2018 2017 Land $ 8,451 $ 6,592 Buildings 255,093 115,302 Computers, equipment, and software 411,177 323,311 Computers, equipment, and software acquired under capital leases 13,848 18,298 Furniture and fixtures 34,809 24,462 Leasehold improvements 132,209 108,673 Property and equipment, gross (1) 855,587 596,638 Less accumulated depreciation and amortization (308,978 ) (230,761 ) Property and equipment, net $ 546,609 $ 365,877 (1) Property and equipment, gross includes construction-in-progress for owned real estate projects of $177 million and $115 million that have not yet been placed in service as of January 31, 2018 and 2017 , respectively.

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Jan. 31, 2018
Business Combinations [Abstract]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair values of assets acquired and liabilities assumed in the business combinations during fiscal 2017 (in thousands): Cash and cash equivalents $ 3,390 Other tangible assets 3,466 Acquired developed technology 45,039 Customer relationship assets 1,000 Accounts payable and other liabilities (3,256 ) Unearned revenue (6,000 ) Net assets acquired 43,639 Goodwill 107,658 Total purchase consideration $ 151,297

Acquisition-related Intangibl38

Acquisition-related Intangible Assets, Net (Tables)	12 Months Ended
	Jan. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Schedule of Acquired Assets	Acquisition-related intangible assets, net consisted of the following (in thousands): January 31, 2018 2017 Acquired developed technology $ 69,700 $ 64,900 Customer relationship assets 1,000 1,000 70,700 65,900 Less accumulated amortization (36,466 ) (17,113 ) Acquisition-related intangible assets, net $ 34,234 $ 48,787
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	As of January 31, 2018, the future estimated amortization expense related to the acquired land leasehold interest and technology patents is as follows (in thousands): 2019 $ 1,678 2020 1,621 2021 1,459 2022 1,242 2023 1,137 Thereafter 13,650 $ 20,787
Acquired developed technology and customer relationship assets
Acquired Finite-Lived Intangible Assets [Line Items]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	As of January 31, 2018 , our future estimated amortization expense related to the acquired developed technology and customer relationship assets is as follows (in thousands): Fiscal Period: 2019 $ 20,086 2020 11,481 2021 1,517 2022 1,150 Total $ 34,234

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Jan. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Assets	Other assets consisted of the following (in thousands): January 31, 2018 2017 Cost method investments $ 29,205 $ 14,004 Prepayments for computing infrastructure platform 13,588 — Technology patents, net 11,217 2,098 Acquired land leasehold interest, net 9,570 9,676 Deposits 4,492 3,488 Net deferred tax assets 1,884 4,336 Other 39,762 19,968 Total $ 109,718 $ 53,570
Summary of Future Estimated Amortization Expense Related to Acquired Leasehold Interest and Patents	As of January 31, 2018, the future estimated amortization expense related to the acquired land leasehold interest and technology patents is as follows (in thousands): 2019 $ 1,678 2020 1,621 2021 1,459 2022 1,242 2023 1,137 Thereafter 13,650 $ 20,787

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Jan. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The fair values of outstanding derivative instruments were as follows (in thousands): Consolidated Balance Sheets Location January 31, 2018 2017 Derivative Assets: Foreign currency forward contracts designated as cash flow hedges Prepaid expenses and other current assets $ 15 $ 7,121 Foreign currency forward contracts designated as cash flow hedges Other assets 4 28 Foreign currency forward contracts not designated as hedges Prepaid expenses and other current assets 79 760 Total Derivative Assets $ 98 $ 7,909 Derivative Liabilities: Foreign currency forward contracts designated as cash flow hedges Accrued expenses and other current liabilities $ 18,355 $ 1,605 Foreign currency forward contracts designated as cash flow hedges Other liabilities 11,650 — Foreign currency forward contracts not designated as hedges Accrued expenses and other current liabilities 2,805 522 Foreign currency forward contracts not designated as hedges Other liabilities 102 — Total Derivative Liabilities $ 32,912 $ 2,127
Derivative Instruments, Gain (Loss)	Gains (losses) associated with foreign currency forward contracts designated as cash flow hedges were as follows (in thousands): Consolidated Statements of Operations and Statements of Comprehensive Loss Locations January 31, 2018 2017 2016 Gains (losses) recognized in OCI (effective portion) (1) Net change in market value of effective foreign currency forward exchange contracts $ (45,869 ) $ 2,145 $ 4,942 Gains (losses) reclassified from OCI into income (effective portion) Revenues 1,509 635 3 Gains (losses) recognized in income (amount excluded from effectiveness testing and ineffective portion) Other income (expense), net 1,607 1,386 148 (1) Of the total effective portion of foreign currency forward contracts designated as cash flow hedges as of January 31, 2018 , net losses of $10 million are expected to be reclassified out of OCI within the next 12 months. Gains (losses) associated with foreign currency forward contracts not designated as cash flow hedges were as follows (in thousands): Consolidated Statements of Operations Location January 31, Derivative Type 2018 2017 2016 Foreign currency forward contracts not designated as hedges Other income (expense), net $ (5,641 ) $ 662 $ 876
Offsetting Assets	As of January 31, 2018 , information related to these offsetting arrangements was as follows (in thousands): Gross Amounts of Recognized Assets Gross Amounts Offset on the Consolidated Balance Sheets Net Amounts of Assets Presented on the Consolidated Balance Sheets Gross Amounts Not Offset on the Consolidated Balance Sheets Net Assets Exposed Financial Instruments Cash Collateral Received Derivative Assets Counterparty A $ 64 $ — $ 64 $ (64 ) $ — $ — Counterparty B 23 — 23 (23 ) — — Counterparty C 11 — 11 (11 ) — — Total $ 98 $ — $ 98 $ (98 ) $ — $ —
Offsetting Liabilities	Gross Amounts of Recognized Liabilities Gross Amounts Offset on the Consolidated Balance Sheets Net Amounts of Liabilities Presented on the Consolidated Balance Sheets Gross Amounts Not Offset on the Consolidated Balance Sheets Net Liabilities Exposed Financial Instruments Cash Collateral Pledged Derivative Liabilities Counterparty A $ 10,267 $ — $ 10,267 $ (64 ) $ — $ 10,203 Counterparty B 16,993 — 16,993 (23 ) — 16,970 Counterparty C 5,652 — 5,652 (11 ) — 5,641 Total $ 32,912 $ — $ 32,912 $ (98 ) $ — $ 32,814

Convertible Senior Notes, Net (

Convertible Senior Notes, Net (Tables)	12 Months Ended
	Jan. 31, 2018
Debt Disclosure [Abstract]
Schedule of Senior Notes	The Notes, net consisted of the following (in thousands): January 31, 2018 January 31, 2017 2018 Notes 2020 Notes 2022 Notes 2018 Notes 2020 Notes 2022 Notes Principal amounts: Principal $ 350,000 $ 250,000 $ 1,150,000 $ 350,000 $ 250,000 $ — Unamortized debt discount (7,850 ) (26,968 ) (208,188 ) (24,380 ) (36,820 ) — Unamortized debt issuance costs (641 ) (1,654 ) (13,345 ) (2,050 ) (2,327 ) — Net carrying amount $ 341,509 $ 221,378 $ 928,467 $ 323,570 $ 210,853 $ — Carrying amount of the equity component (1) $ 74,892 $ 66,007 $ 219,702 $ 74,892 $ 66,007 $ — (1) Included on the consolidated balance sheets within Additional paid-in capital, net of $2 million , $2 million , and $4 million for the 2018 Notes, 2020 Notes, and 2022 Notes, respectively, in equity issuance costs.
Schedule of Interest Expense Recognized Related to Convertible Senior Notes	The following table sets forth total interest expense recognized related to the Notes (in thousands): Year Ended January 31, 2018 2017 2018 Notes 2020 Notes 2022 Notes 2018 Notes 2020 Notes 2022 Notes Contractual interest expense $ 2,625 $ 3,750 $ 1,086 $ 2,625 $ 3,750 $ — Interest cost related to amortization of debt issuance costs 1,409 673 1,080 1,408 675 — Interest cost related to amortization of the debt discount 16,530 9,852 14,989 15,607 9,257 —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Jan. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Payments by Year for our Non-Cancelable Leases and Computing Infrastructure Platforms	As of January 31, 2018 , the future minimum payments by year for our non-cancelable leases and computing infrastructure platforms are as follows (in thousands): Operating Operating Computing Infrastructure Platforms 2019 $ 59,204 $ 11,103 $ 7,461 2020 40,920 12,692 5,500 2021 35,808 12,977 11,000 2022 25,747 13,265 14,000 2023 13,590 13,556 15,250 Thereafter 28,951 20,661 34,250 $ 204,220 $ 84,254 $ 87,461

Common Stock and Stockholders43

Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Jan. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Information Related to Restricted Stock Units Activity	A summary of information related to RSU activity during fiscal 2018 is as follows: Number of Shares Weighted-Average Balance as of January 31, 2017 11,502,721 $ 78.45 RSUs granted 7,736,434 88.90 RSUs vested (5,412,921 ) 78.26 RSUs forfeited (1,006,718 ) 79.34 Balance as of January 31, 2018 12,819,516 $ 84.77
Summary of Stock Option Activity	A summary of information related to stock option activity during fiscal 2018 is as follows (in millions, except share and per share data): Outstanding Weighted- Aggregate Balance as of January 31, 2017 9,096,592 $ 4.34 $ 716 Stock option grants — — Stock options exercised (2,490,931 ) 4.60 Stock options canceled (10,175 ) 7.76 Balance as of January 31, 2018 6,595,486 $ 4.23 $ 763 Vested and expected to vest as of January 31, 2018 6,595,469 $ 4.23 $ 763 Exercisable as of January 31, 2018 6,594,986 $ 4.23 $ 763
Assumptions Used for Periods Presented	The fair value of stock purchase rights granted under the ESPP was estimated using the following assumptions: Year Ended January 31, 2018 2017 2016 Expected volatility 25.3% – 32.0% 34.5% – 44.5% 32.0% – 34.2% Expected term (in years) 0.5 0.5 0.5 Risk-free interest rate 1.11% – 1.45% 0.53% – 0.91% 0.26% – 0.51% Dividend yield —% —% —% Weighted-average grant date fair value per share $98.39 – $100.52 $69.00 – $79.30 $67.23 – $71.81

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	12 Months Ended
	Jan. 31, 2018
Other Income and Expenses [Abstract]
Schedule of Other Income (Expense), Net	Other income (expense), net consisted of the following (in thousands): Year Ended January 31, 2018 2017 2016 Interest income $ 25,252 $ 11,303 $ 4,855 Interest expense (1) (44,549 ) (30,103 ) (31,932 ) Gain from sale of cost method investment 720 65 3,220 Impairment of cost method investment (692 ) (15,000 ) — Other income (expense) 7,706 1,308 (385 ) Other income (expense), net $ (11,563 ) $ (32,427 ) $ (24,242 ) (1) Interest expense includes the contractual interest expense related to the 2018 Notes, 2020 Notes, and 2022 Notes and non-cash interest expense related to amortization of the debt discount and debt issuance costs, net of capitalized interest costs (see Note 11).

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Jan. 31, 2018
Income Tax Disclosure [Abstract]
Components of Loss before Provision for (Benefit from) Income Taxes	The components of loss before provision for (benefit from) income taxes were as follows (in thousands): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Domestic $ (85,167 ) $ (190,043 ) $ (119,302 ) Foreign (229,619 ) (195,470 ) (154,729 ) Total $ (314,786 ) $ (385,513 ) $ (274,031 )
Summary of Provision for (Benefit from) Income Taxes	The provision for (benefit from) income taxes consisted of the following (in thousands): Year Ended January 31, 2018 2017 2016 Current: Federal $ — $ 213 $ (2,012 ) State 177 17 489 Foreign 4,251 3,573 2,869 Total 4,428 3,803 1,346 Deferred: Federal (535 ) (466 ) — State (100 ) (52 ) — Foreign 2,643 (4,099 ) (329 ) Total 2,008 (4,617 ) (329 ) Provision for (benefit from) income taxes $ 6,436 $ (814 ) $ 1,017
Reconciliation of Income Taxes Computed at Federal Statutory Income Tax Rate and Provision for (Benefit from) Income Taxes	The items accounting for the difference between income taxes computed at the federal statutory income tax rate and the provision for (benefit from) income taxes consisted of the following: Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Federal statutory rate 33.8 % 35.0 % 35.0 % Effect of: Foreign income at other than U.S. rates (26.5 )% (18.5 )% (25.7 )% Intercompany transactions 10.2 % 4.2 % 5.2 % Research tax credits 9.1 % 6.4 % 5.1 % State taxes, net of federal benefit — % — % (0.2 )% U.S. corporate tax rate reduction (81.3 )% — % — % Changes in valuation allowance 33.0 % (20.4 )% (15.1 )% Stock compensation 20.0 % (6.1 )% (5.4 )% Other (0.4 )% (0.4 )% 0.7 % (2.1 )% 0.2 % (0.4 )% * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2.
Schedule of Deferred Tax Assets and Liabilities	Significant components of our deferred tax assets and liabilities were as follows (in thousands): January 31, 2018 2017 *As Adjusted Deferred tax assets: Unearned revenue $ 27,934 $ 40,810 Other reserves and accruals 14,945 23,134 Federal net operating loss carryforwards 422,235 110,974 State and foreign net operating loss carryforwards 81,757 25,783 Property and equipment — 24,754 Share-based compensation 39,294 70,642 Research and development credits 110,694 78,283 Other 5,622 23,209 702,481 397,589 Valuation allowance (625,030 ) (292,365 ) Deferred tax assets, net of valuation allowance 77,451 105,224 Deferred tax liabilities: Intangibles (1,453 ) (3,742 ) Intercompany transactions (40,338 ) (62,800 ) Other prepaid assets (742 ) (1,079 ) Deferred commissions (29,231 ) (33,267 ) Property and equipment (3,803 ) — (75,567 ) (100,888 ) Net deferred tax assets $ 1,884 $ 4,336 * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2.
Summary of Reconciliation of Gross Unrecognized Tax Benefit	A reconciliation of the gross unrecognized tax benefit is as follows (in thousands): Year Ended January 31, 2018 2017 2016 Unrecognized tax benefits at the beginning of the period $ 116,801 $ 98,460 $ 88,663 Additions for tax positions taken in prior years 1,500 3,981 2,818 Reductions for tax positions taken in prior years (8,121 ) — (881 ) Decrease for tax positions taken in prior years due to federal rate reduction (10,062 ) — — Additions for tax positions related to the current year 7,731 14,475 9,144 Reductions related to a lapse of applicable statute of limitations — (115 ) (1,284 ) Unrecognized tax benefits at the end of the period $ 107,849 $ 116,801 $ 98,460

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Jan. 31, 2018
Earnings Per Share [Abstract]
Summary of Calculation of Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss attributable to common stockholders per share (in thousands, except per share data): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted Class A Class B Class A Class B Class A Class B Basic and diluted net loss attributable to Class A and Class B common stockholders per share: Numerator: Allocation of distributed net loss attributable to common stockholders $ (208,159 ) $ (113,063 ) $ (236,946 ) $ (147,753 ) $ (160,173 ) $ (114,875 ) Denominator: Weighted-average common shares outstanding 134,642 73,132 122,085 76,129 110,655 79,361 Basic and diluted net loss per share $ (1.55 ) $ (1.55 ) $ (1.94 ) $ (1.94 ) $ (1.45 ) $ (1.45 ) * See Note 2 for a summary of adjustments.
Anti-dilutive securities excluded from the diluted calculation	The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share were as follows (in thousands): Year Ended January 31, 2018 2017 2016 Outstanding common stock options 6,595 9,097 12,863 Shares subject to repurchase — 110 621 Unvested restricted stock awards, units, and PRSUs 13,209 12,155 9,851 Shares related to the convertible senior notes 15,079 7,261 7,261 Shares subject to warrants related to the issuance of convertible senior notes 15,079 7,261 7,261 Shares issuable pursuant to the ESPP 466 485 345 50,428 36,369 38,202

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
	Jan. 31, 2018
Segment Reporting [Abstract]
Summary of Revenues by Geographic Area and Long Lived Assets by Geographic Areas	The following table sets forth revenue by geographic area (in thousands): Year Ended January 31, 2018 2017 2016 *As Adjusted *As Adjusted United States $ 1,694,347 $ 1,283,475 $ 966,250 Other countries 448,703 290,965 190,440 Total $ 2,143,050 $ 1,574,440 $ 1,156,690 * Adjusted to reflect the adoption of ASU No. 2014-09, Revenue from Contracts with Customers. For further information, see Note 2. Long-Lived Assets We attribute our long-lived assets, which primarily consist of property and equipment, to a country based on the physical location of the assets. The following table sets forth property and equipment by geographic area (in thousands): January 31, 2018 2017 United States $ 479,996 $ 321,442 Ireland 52,904 35,720 Other countries 13,709 8,715 Total $ 546,609 $ 365,877

Selected Quarterly Financial 48

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Jan. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Consolidated Statements of Operations Data	The following tables set forth selected unaudited quarterly consolidated statements of operations data for each of the eight quarters in fiscal 2018 and 2017 (in thousands except per share data): Quarter ended January 31, 2018 October 31, 2017 July 31, 2017 April 30, 2017 January 31, 2017 October 31, 2016 July 31, 2016 April 30, 2016 *As Adjusted *As Adjusted *As Adjusted *As Adjusted Consolidated Statements of Operations Data: Total revenues $ 582,480 $ 555,389 $ 525,320 $ 479,861 $ 439,584 $ 413,522 $ 373,657 $ 347,677 Operating loss (81,335 ) (80,059 ) (81,629 ) (60,200 ) (88,939 ) (105,932 ) (86,685 ) (71,530 ) Net loss (89,100 ) (85,546 ) (82,532 ) (64,044 ) (88,269 ) (110,114 ) (107,813 ) (78,503 ) Net loss per share, basic and diluted (0.42 ) (0.41 ) (0.40 ) (0.31 ) (0.44 ) (0.55 ) (0.55 ) (0.40 ) * See Note 2 for a summary of adjustments.

Overview and Basis of Present49

Overview and Basis of Presentation (Detail)	12 Months Ended
	Jan. 31, 2018segment
Accounting Policies [Abstract]
Number of operating segments	1

Accounting Standards and Sign50

Accounting Standards and Significant Accounting Policies (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016	Sep. 30, 2017	Jun. 30, 2013
Accounting Policies [Line Items]
Subscriptions contract period, years	3 years
Period to pay portion of total arrangement fee, days	30 days
Current unearned revenue anticipated recognition term, months	12 months
Advertising expense	$ 43,000,000	$ 35,000,000	$ 31,000,000
2018 Notes
Accounting Policies [Line Items]
Convertible senior notes, interest rate	0.75%				0.75%
Convertible Senior Notes, principal amount	$ 350,000,000	350,000,000			$ 350,000,000
2020 Notes
Accounting Policies [Line Items]
Convertible senior notes, interest rate	1.50%				1.50%
Convertible Senior Notes, principal amount	$ 250,000,000	250,000,000			$ 250,000,000
2022 Notes
Accounting Policies [Line Items]
Convertible senior notes, interest rate	0.25%			0.25%
Convertible Senior Notes, principal amount	$ 1,150,000,000	$ 0		$ 1,150,000,000
Minimum
Accounting Policies [Line Items]
Intangible assets, useful life, years	3 years
Maximum
Accounting Policies [Line Items]
Intangible assets, useful life, years	4 years

Accounting Standards and Sign51

Accounting Standards and Significant Accounting Policies (Detail 2) - USD ($) $ in Thousands		Feb. 01, 2017	Jan. 31, 2018	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation allowance			$ 625,030	$ 292,365
Cumulative effect of new accounting principle	[1]		$ 231
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization period, deferred commissions			3 years
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization period, deferred commissions			5 years
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess benefit amount		$ 448,000
Valuation allowance		447,800
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows increase (decrease)				$ 2,000
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle	[1]		$ 231
Accumulated Deficit | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle		$ 200
[1]	See Note 2 for a summary of adjustments.

Accounting Standards and Sign52

Accounting Standards and Significant Accounting Policies (Adjustments to the Balance Sheet) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Assets
Trade and other receivables, net	$ 528,208	$ 409,780	[1]
Prepaid expenses and other current assets	97,860	66,590	[1]
Deferred costs	63,060	51,330	[1]
Deferred costs, noncurrent	140,509	117,249	[1]
Liabilities
Unearned revenue	1,426,241	1,086,212	[1]
Unearned revenue, noncurrent	$ 110,906	135,331	[1]
As Previously Reported
Assets
Trade and other receivables, net		383,908
Prepaid expenses and other current assets		88,336
Deferred costs		27,537
Deferred costs, noncurrent		43,310
Liabilities
Unearned revenue		1,097,417
Unearned revenue, noncurrent		135,970
Adjustments | Adjustments
Assets
Trade and other receivables, net		25,872
Prepaid expenses and other current assets		(21,746)
Deferred costs		23,793
Deferred costs, noncurrent		73,939
Liabilities
Unearned revenue		(11,205)
Unearned revenue, noncurrent		$ (639)
[1]	See Note 2 for a summary of adjustments.

Accounting Standards and Sign53

Accounting Standards and Significant Accounting Policies (Adjustments to the Income Statement) (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018		Jan. 31, 2017		Jan. 31, 2016
Revenues [Abstract]
Subscription services										$ 1,787,833		$ 1,290,733	[1]	$ 920,196	[1]
Professional services										355,217		283,707	[1]	236,494	[1]
Total revenues		$ 582,480	$ 555,389	$ 525,320	$ 479,861	$ 439,584	$ 413,522	$ 373,657	$ 347,677	2,143,050		1,574,440	[1]	1,156,690	[1]
Costs and expenses:
Sales and marketing	[2]									683,367		565,328	[1]	413,530	[1]
Operating loss		(81,335)	(80,059)	(81,629)	(60,200)	(88,939)	(105,932)	(86,685)	(71,530)	(303,223)		(353,086)	[1]	(249,789)	[1]
Net loss		$ (89,100)	$ (85,546)	$ (82,532)	$ (64,044)	$ (88,269)	$ (110,114)	$ (107,813)	$ (78,503)	$ (321,222)	[1]	$ (384,699)	[1]	$ (275,048)	[1]
Net loss per share, basic and diluted (dollars per share)		$ (0.42)	$ (0.41)	$ (0.40)	$ (0.31)	$ (0.44)	$ (0.55)	$ (0.55)	$ (0.40)	$ (1.55)		$ (1.94)	[1]	$ (1.45)	[1]
As Previously Reported
Revenues [Abstract]
Subscription services												$ 1,287,104		$ 929,234
Professional services												282,303		233,112
Total revenues												1,569,407		1,162,346
Costs and expenses:
Sales and marketing												583,874		434,056
Operating loss												(376,665)		(264,659)
Net loss												$ (408,278)		$ (289,918)
Net loss per share, basic and diluted (dollars per share)												$ (2.06)		$ (1.53)
Adjustments | Adjustments
Revenues [Abstract]
Subscription services												$ 3,629		$ (9,038)
Professional services												1,404		3,382
Total revenues												5,033		(5,656)
Costs and expenses:
Sales and marketing												(18,546)		(20,526)
Operating loss												23,579		14,870
Net loss												$ 23,579		$ 14,870
Net loss per share, basic and diluted (dollars per share)												$ 0.12		$ 0.08
[1]	See Note 2 for a summary of adjustments.
[2]	Costs and expenses include share-based compensation expenses as follows: Costs of subscription services $26,280 $20,773 $12,060 Costs of professional services $37,592 $26,833 $19,526 Product development $229,819 $166,529 $109,362 Sales and marketing $100,762 $86,229 $51,617 General and administrative $83,972 $78,265 $57,405

Accounting Standards and Sign54

Accounting Standards and Significant Accounting Policies (Adjustments to the Statement of Cash Flows) (Detail) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017		Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018		Jan. 31, 2017		Jan. 31, 2016		Jan. 31, 2015	[1]
Cash flows from operating activities
Net loss	$ (89,100)	$ (85,546)	$ (82,532)	$ (64,044)	$ (88,269)		$ (110,114)	$ (107,813)	$ (78,503)	$ (321,222)	[1]	$ (384,699)	[1]	$ (275,048)	[1]
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred costs										57,562		45,345	[1]	36,016	[1]
Trade and other receivables, net										(114,613)		(91,755)	[1]	(115,776)	[1]
Deferred costs										(92,552)		(82,848)	[1]	(66,964)	[1]
Prepaid expenses and other assets										(68,983)		(16,794)	[1]	(20,121)	[1]
Unearned revenue										315,584		323,617	[1]	274,728	[1]
Net cash provided by (used in) operating activities										465,727		350,626	[1]	258,637	[1]
Net increase (decrease) in cash, cash equivalents, and restricted cash										593,760		241,807	[1]	1,895	[1]
Cash, cash equivalents, and restricted cash at the end of period	$ 1,135,654				541,894	[1]				$ 1,135,654		541,894	[1]	300,087	[1]	$ 298,192
As Previously Reported
Cash flows from operating activities
Net loss												(408,278)		(289,918)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred costs												25,577		23,477
Trade and other receivables, net												(88,639)		(105,264)
Deferred costs												(44,533)		(33,899)
Prepaid expenses and other assets												(20,847)		(28,366)
Unearned revenue												327,615		266,805
Net cash provided by (used in) operating activities												348,655		258,637
Net increase (decrease) in cash, cash equivalents, and restricted cash												239,836
Cash, cash equivalents, and restricted cash at the end of period					539,923							539,923
Adjustments | Adjustments
Cash flows from operating activities
Net loss												23,579		14,870
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred costs												19,768		12,539
Trade and other receivables, net												(3,116)		(10,512)
Deferred costs												(38,315)		(33,065)
Prepaid expenses and other assets												4,053		8,245
Unearned revenue												(3,998)		7,923
Net cash provided by (used in) operating activities												1,971		$ 0
Net increase (decrease) in cash, cash equivalents, and restricted cash												1,971
Cash, cash equivalents, and restricted cash at the end of period					$ 1,971							$ 1,971
[1]	See Note 2 for a summary of adjustments.

Marketable Securities (Summary

Marketable Securities (Summary of Marketable Securities) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 3,106,318	$ 1,738,705
Unrealized Gains	16	269
Unrealized Losses	(3,423)	(989)
Aggregate Fair Value	3,102,911	1,737,985
U.S. agency obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	683,551	908,874
Unrealized Gains	0	179
Unrealized Losses	(1,127)	(535)
Aggregate Fair Value	682,424	908,518
U.S. treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	797,977	192,028
Unrealized Gains	0	48
Unrealized Losses	(1,142)	(25)
Aggregate Fair Value	796,835	192,051
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	470,259	290,272
Unrealized Gains	16	42
Unrealized Losses	(1,154)	(429)
Aggregate Fair Value	469,121	289,885
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	602,727	323,106
Unrealized Gains	0	0
Unrealized Losses	0	0
Aggregate Fair Value	602,727	323,106
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	551,804	24,425
Unrealized Gains	0	0
Unrealized Losses	0	0
Aggregate Fair Value	551,804	24,425
Included in cash and cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	969,417	281,163
Unrealized Gains	0	0
Unrealized Losses	(1)	0
Aggregate Fair Value	969,416	281,163
Included in marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,136,901	1,457,542
Unrealized Gains	16	269
Unrealized Losses	(3,422)	(989)
Aggregate Fair Value	$ 2,133,495	$ 1,456,822

Marketable Securities (Narrativ

Marketable Securities (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Sales of available-for-sale securities	$ 243,727	$ 133,292	[1]	$ 102,711	[1]
[1]	See Note 2 for a summary of adjustments.

Fair Value Measurements (Inform

Fair Value Measurements (Information about Assets and Liabilities that are Measured at Fair Value on a Recurring Basis) (Detail) - Recurring - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 3,103,009	$ 1,745,894
Total liabilities	32,912	2,127
U.S. agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	682,424	908,518
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	796,835	192,051
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	469,121	289,885
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	602,727	323,106
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	551,804	24,425
Foreign currency derivative assets and liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	98	7,909
Total liabilities	32,912	2,127
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,348,639	216,476
Total liabilities	0	0
Level 1 | U.S. agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	796,835	192,051
Level 1 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	551,804	24,425
Level 1 | Foreign currency derivative assets and liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,754,370	1,529,418
Total liabilities	32,912	2,127
Level 2 | U.S. agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	682,424	908,518
Level 2 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	469,121	289,885
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	602,727	323,106
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 | Foreign currency derivative assets and liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	98	7,909
Total liabilities	32,912	2,127
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Level 3 | U.S. agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 | Foreign currency derivative assets and liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	$ 0	$ 0

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Sep. 30, 2017	Jan. 31, 2017	Jun. 30, 2013
0.75% Convertible senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Carrying Amount	$ 341,509		$ 323,570
Estimated Fair Value	$ 504,994		402,259
Contractual interest rate	0.75%			0.75%
1.50% Convertible senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Carrying Amount	$ 221,378		210,853
Estimated Fair Value	$ 385,550		310,470
Contractual interest rate	1.50%			1.50%
0.25% Convertible senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net Carrying Amount	$ 928,467		0
Estimated Fair Value	$ 1,200,577		$ 0
Contractual interest rate	0.25%	0.25%

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Jan. 31, 2018USD ($)$ / shares
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Closing price of company's common stock, dollars per share | $ / shares	$ 119.89
2018 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Senior Notes, if-converted excess of principal amount	$ 154
2020 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Senior Notes, if-converted excess of principal amount	117
2022 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Senior Notes, if-converted, less than principal amount	$ 213

Deferred Costs (Detail)

Deferred Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016	[1]
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred costs, sales commissions	$ 204,000	$ 169,000
Amortization of deferred costs	$ 57,562	$ 45,345	[1]	$ 36,016
[1]	See Note 2 for a summary of adjustments.

Property and Equipment, Net (Su

Property and Equipment, Net (Summary of Property and Equipment) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 855,587	$ 596,638
Less accumulated depreciation and amortization	(308,978)	(230,761)
Property, Plant and Equipment, Net	546,609	365,877	[1]
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8,451	6,592
Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	255,093	115,302
Computers, equipment, and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	411,177	323,311
Computers, equipment, and software acquired under capital leases
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	13,848	18,298
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	34,809	24,462
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	132,209	108,673
Construction in Progress for owned real estate projects
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 177,000	$ 115,000
[1]	See Note 2 for a summary of adjustments.

Property and Equipment, Net (Na

Property and Equipment, Net (Narrative) (Detail) ft² in Thousands, $ in Millions	12 Months Ended
	Jan. 31, 2018USD ($)	Jan. 31, 2017USD ($)ft²building	Jan. 31, 2016USD ($)
Property, Plant and Equipment [Abstract]
Number of properties purchased | building		2
Area of real estate property | ft²		267
Depreciation expense	$ 115	$ 92	$ 71
Interest costs capitalized to property and equipment	$ 8	$ 3

Business Combinations (Summary

Business Combinations (Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed) (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Jan. 31, 2018USD ($)	Jan. 31, 2018USD ($)	Jan. 31, 2017USD ($)acquistion		Jan. 31, 2016USD ($)	[1]
Business Acquisition [Line Items]
Intangible assets, gross	$ 70,700	$ 70,700	$ 65,900
Number of businesses acquired | acquistion			2
Business combinations, net of cash acquired		5,744	$ 147,879	[1]	$ 31,436
Goodwill	159,376	159,376	158,354	[1]
Fiscal 2017 Business Acquisitions
Business Acquisition [Line Items]
Cash and cash equivalents			3,390
Other tangible assets			3,466
Accounts payable and other liabilities			(3,256)
Unearned revenue			(6,000)
Net assets acquired			43,639
Goodwill			107,658
Total purchase consideration			151,297
Acquired developed technology
Business Acquisition [Line Items]
Intangible assets, gross	69,700	69,700	64,900
Acquired developed technology | Business Acquisition, Fourth Quarter FY 2018
Business Acquisition [Line Items]
Intangible assets, gross	5,000	5,000
Goodwill, period increase (decrease)	1,000
Acquired developed technology | Fiscal 2017 Business Acquisitions
Business Acquisition [Line Items]
Acquired intangible assets			45,039
Customer relationship assets
Business Acquisition [Line Items]
Intangible assets, gross	$ 1,000	$ 1,000	1,000
Customer relationship assets | Fiscal 2017 Business Acquisitions
Business Acquisition [Line Items]
Acquired intangible assets			$ 1,000
[1]	See Note 2 for a summary of adjustments.

Acquisition-related Intangibl64

Acquisition-related Intangible Assets, Net (Schedule of Acquired Assets) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 70,700	$ 65,900
Less accumulated amortization	(36,466)	(17,113)
Acquisition-related intangible assets, net	34,234	48,787
Acquired developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	69,700	64,900
Customer relationship assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	1,000	1,000
Acquired developed technology and customer relationship assets
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 19,000	$ 13,000	$ 3,000

Acquisition-related Intangibl65

Acquisition-related Intangible Assets, Net (Schedule of Future Amortization Expense) (Detail) - Acquired developed technology and customer relationship assets $ in Thousands	Jan. 31, 2018USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
2,019	$ 20,086
2,020	11,481
2,021	1,517
2,022	1,150
Total	$ 34,234

Other Assets (Schedule of Other

Other Assets (Schedule of Other Assets) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Cost method investments	$ 29,205	$ 14,004
Prepayments for computing infrastructure platforms	13,588	0
Acquired land leasehold interest, net	9,570	9,676
Deposits	4,492	3,488
Net deferred tax assets	1,884	4,336
Other	39,762	19,968
Total	109,718	53,570	[1]
Technology patents, net
Finite-Lived Intangible Assets [Line Items]
Technology patents, net	$ 11,217	$ 2,098
[1]	See Note 2 for a summary of adjustments.

Other Assets (Narrative) (Detai

Other Assets (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Impairment of cost method investment	$ 692	$ 15,000	[1]	$ 0	[1]
[1]	See Note 2 for a summary of adjustments.

Other Assets (Summary of Future

Other Assets (Summary of Future Estimated Amortization Expense Related to Acquired Land Leasehold Interest and Technology Patents) (Detail) - Acquired Land Leasehold Interest And Technology Patents $ in Thousands	Jan. 31, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
2,019	$ 1,678
2,020	1,621
2,021	1,459
2,022	1,242
2,023	1,137
Thereafter	13,650
Total	$ 20,787

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Detail) - Forward Contracts - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	$ 549	$ 252
Designated as Hedging Instrument | Maximum
Derivative [Line Items]
Derivative, remaining maturity	36 months
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	$ 75	$ 51

Derivative Instruments (Fair Va

Derivative Instruments (Fair Values of Outstanding Derivative Instruments) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 98	$ 7,909
Derivative Liabilities	32,912	2,127
Forward Contracts | Designated as Hedging Instrument | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	15	7,121
Forward Contracts | Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	4	28
Forward Contracts | Designated as Hedging Instrument | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	18,355	1,605
Forward Contracts | Designated as Hedging Instrument | Other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	11,650	0
Forward Contracts | Not Designated as Hedging Instrument | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	79	760
Forward Contracts | Not Designated as Hedging Instrument | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2,805	522
Forward Contracts | Not Designated as Hedging Instrument | Other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 102	$ 0

Derivative Instruments (Gains (

Derivative Instruments (Gains (losses) Associated with Foreign Currency Forward Contracts) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) expected to be reclassified from accumulated OCI within the next 12 months	$ (10,000)
Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency forward contracts not designated as hedges	(5,641)	$ 662	$ 876
Designated as Hedging Instrument | Revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reclassified from OCI into income (effective portion)	1,509	635	3
Designated as Hedging Instrument | Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in income (amount excluded from effectiveness testing and ineffective portion)	1,607	1,386	148
Designated as Hedging Instrument | Net change in market value of effective foreign currency forward exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in OCI (effective portion)	$ (45,869)	$ 2,145	$ 4,942

Derivative Instruments (Offsett

Derivative Instruments (Offsetting Assets) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	$ 98	$ 7,909
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Assets Presented on the Consolidated Balance Sheets	98
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(98)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0
Net Assets Exposed	0
Counterparty A
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	64
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Assets Presented on the Consolidated Balance Sheets	64
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(64)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0
Net Assets Exposed	0
Counterparty B
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	23
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Assets Presented on the Consolidated Balance Sheets	23
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(23)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0
Net Assets Exposed	0
Counterparty C
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	11
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Assets Presented on the Consolidated Balance Sheets	11
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(11)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	0
Net Assets Exposed	$ 0

Derivative Instruments (Offse73

Derivative Instruments (Offsetting Liabilities) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ 32,912	$ 2,127
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented on the Consolidated Balance Sheets	32,912
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(98)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	32,814
Counterparty A
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	10,267
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented on the Consolidated Balance Sheets	10,267
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(64)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	10,203
Counterparty B
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	16,993
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented on the Consolidated Balance Sheets	16,993
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(23)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	16,970
Counterparty C
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	5,652
Gross Amounts Offset on the Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented on the Consolidated Balance Sheets	5,652
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	(11)
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	$ 5,641

Convertible Senior Notes, Net74

Convertible Senior Notes, Net (Detail) $ / shares in Units, shares in Millions	12 Months Ended
	Jan. 31, 2018USD ($)trading_day$ / sharesshares	Jan. 31, 2017USD ($)		Jan. 31, 2016USD ($)	[1]	Sep. 30, 2017USD ($)	Jun. 30, 2013USD ($)
Debt Instrument [Line Items]
Interest costs capitalized	$ 8,000,000	$ 3,000,000
Proceeds from sale of warrants	$ 80,805,000	0	[1]	$ 0
2018 Notes
Debt Instrument [Line Items]
Contractual interest rate	0.75%						0.75%
Convertible Senior Notes, principal amount	$ 350,000,000	350,000,000					$ 350,000,000
Debt issuance costs	7,000,000
Equity issuance costs	2,000,000
Amortization expense for debt issuance costs	$ 1,409,000	1,408,000
Remaining life of the notes, months	5 months
Effective interest rates of the liability components, percentage	5.75%
2018 Notes | Class A Common Stock
Debt Instrument [Line Items]
Initial conversion rate	12.0075
Principal amount converted into Class A Common Stock	$ 1,000
Initial conversion price (in dollars per share) | $ / shares	$ 83.28
Converted shares issued (in shares) | shares	4.2
2020 Notes
Debt Instrument [Line Items]
Contractual interest rate	1.50%						1.50%
Convertible Senior Notes, principal amount	$ 250,000,000	250,000,000					$ 250,000,000
Debt issuance costs	5,000,000
Equity issuance costs	2,000,000
Amortization expense for debt issuance costs	$ 673,000	675,000
Remaining life of the notes, months	29 months
Effective interest rates of the liability components, percentage	6.25%
2020 Notes | Class A Common Stock
Debt Instrument [Line Items]
Initial conversion rate	12.2340
Principal amount converted into Class A Common Stock	$ 1,000
Initial conversion price (in dollars per share) | $ / shares	$ 81.74
Converted shares issued (in shares) | shares	3.1
2022 Notes
Debt Instrument [Line Items]
Contractual interest rate	0.25%					0.25%
Convertible Senior Notes, principal amount	$ 1,150,000,000	0				$ 1,150,000,000
Debt issuance costs	14,000,000
Equity issuance costs	4,000,000
Amortization expense for debt issuance costs	$ 1,080,000	$ 0
Remaining life of the notes, months	56 months
Effective interest rates of the liability components, percentage	4.60%
Aggregate amount paid for Purchased Options	$ 176,000,000
Proceeds from sale of warrants	$ 81,000,000
2022 Notes | Class A Common Stock
Debt Instrument [Line Items]
Initial conversion rate	6.7982
Principal amount converted into Class A Common Stock	$ 1,000
Initial conversion price (in dollars per share) | $ / shares	$ 147.10
Converted shares issued (in shares) | shares	7.8
Convertible Senior Notes
Debt Instrument [Line Items]
Repurchase of notes percentage	100.00%
Convertible Senior Notes | Debt Conversion, Option One
Debt Instrument [Line Items]
Threshold trading days (in trading days) | trading_day	20
Threshold consecutive trading days | trading_day	30
Threshold percentage of conversion price	130.00%
Convertible Senior Notes | Debt Conversion, Option Two
Debt Instrument [Line Items]
Threshold consecutive trading days | trading_day	5
Convertible Senior Notes | Debt Conversion, Option Two | Maximum
Debt Instrument [Line Items]
Threshold percentage of conversion price	98.00%
Notes 2018 and 2020
Debt Instrument [Line Items]
Aggregate amount paid for Purchased Options	$ 144,000,000
Proceeds from sale of warrants	$ 93,000,000
Warrants Expires in October 2018
Debt Instrument [Line Items]
Shares covered by each purchased option/warrant, shares | shares	4.2
Trading days	60 days
Exercise price of warrants, dollars per share | $ / shares	$ 107.96
Warrants Expires In October 2020
Debt Instrument [Line Items]
Shares covered by each purchased option/warrant, shares | shares	3.1
Trading days	60 days
Exercise price of warrants, dollars per share | $ / shares	$ 107.96
Warrants Expires In January 2023
Debt Instrument [Line Items]
Shares covered by each purchased option/warrant, shares | shares	7.8
Trading days	60 days
Exercise price of warrants, dollars per share | $ / shares	$ 213.96
[1]	See Note 2 for a summary of adjustments.

Convertible Senior Notes, Net75

Convertible Senior Notes, Net (Schedule of Senior Notes) (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2018	Sep. 30, 2017	Jan. 31, 2017		Jun. 30, 2013
Debt Instrument [Line Items]
Net carrying amount, current	$ 341,509,000		$ 0	[1]
Net carrying amount, noncurrent	1,149,845,000		534,423,000	[1]
2018 Notes
Debt Instrument [Line Items]
Principal	350,000,000		350,000,000		$ 350,000,000
Unamortized debt discount	(7,850,000)		(24,380,000)
Unamortized debt issuance costs	(641,000)		(2,050,000)
Net carrying amount, current	341,509,000
Net carrying amount, noncurrent			323,570,000
Carrying amount of the equity component	74,892,000		74,892,000
Equity issuance costs	2,000,000
2020 Notes
Debt Instrument [Line Items]
Principal	250,000,000		250,000,000		$ 250,000,000
Unamortized debt discount	(26,968,000)		(36,820,000)
Unamortized debt issuance costs	(1,654,000)		(2,327,000)
Net carrying amount, noncurrent	221,378,000		210,853,000
Carrying amount of the equity component	66,007,000		66,007,000
Equity issuance costs	2,000,000
2022 Notes
Debt Instrument [Line Items]
Principal	1,150,000,000	$ 1,150,000,000	0
Unamortized debt discount	(208,188,000)		0
Unamortized debt issuance costs	(13,345,000)		0
Net carrying amount, noncurrent	928,467,000		0
Carrying amount of the equity component	219,702,000		$ 0
Equity issuance costs	$ 4,000,000
[1]	See Note 2 for a summary of adjustments.

Convertible Senior Notes, Net76

Convertible Senior Notes, Net (Schedule of Interest Expense Recognized Related to Convertible Senior Notes) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016	[1]
Debt Instrument [Line Items]
Interest cost related to amortization of the debt discount	$ 43,916	$ 26,947	[1]	$ 25,518
2018 Notes
Debt Instrument [Line Items]
Contractual interest expense	2,625	2,625
Interest cost related to amortization of debt issuance costs	1,409	1,408
Interest cost related to amortization of the debt discount	16,530	15,607
2020 Notes
Debt Instrument [Line Items]
Contractual interest expense	3,750	3,750
Interest cost related to amortization of debt issuance costs	673	675
Interest cost related to amortization of the debt discount	9,852	9,257
2022 Notes
Debt Instrument [Line Items]
Contractual interest expense	1,086	0
Interest cost related to amortization of debt issuance costs	1,080	0
Interest cost related to amortization of the debt discount	$ 14,989	$ 0
[1]	See Note 2 for a summary of adjustments.

Commitments and Contingencies77

Commitments and Contingencies (Narrative) (Detail) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2014USD ($)a	Jan. 31, 2018USD ($)	Jan. 31, 2017USD ($)	Jan. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Rent expense		$ 82	$ 72	$ 46
Lease term period, in years	95 years
Parcel of vacant land | a	6.9
Lease rent, prepaid	$ 2
Annual rent payments, beginning in 2021		$ 0.2

Commitments and Contingencies78

Commitments and Contingencies (Future Minimum Lease Payments by Year under Non-Cancelable Leases and Computing Infrastructure Platforms) (Detail) $ in Thousands	Jan. 31, 2018USD ($)
Operating Leased Assets and Non-Leased Assets [Line Items]
2,019	$ 59,204
2,020	40,920
2,021	35,808
2,022	25,747
2,023	13,590
Thereafter	28,951
Operating leases	204,220
Computing Infrastructure Platforms
Operating Leased Assets and Non-Leased Assets [Line Items]
2,019	7,461
2,020	5,500
2,021	11,000
2,022	14,000
2,023	15,250
Thereafter	34,250
Operating leases	87,461
Related Party
Operating Leased Assets and Non-Leased Assets [Line Items]
2,019	11,103
2,020	12,692
2,021	12,977
2,022	13,265
2,023	13,556
Thereafter	20,661
Operating leases	$ 84,254

Common Stock and Stockholders79

Common Stock and Stockholders' Equity (Narrative) (Detail) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2017shares	Jan. 31, 2018USD ($)vote / shares$ / sharesshares	Jan. 31, 2017USD ($)$ / sharesshares	Jan. 31, 2016USD ($)$ / shares
Employee Stock Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share reserve increased, shares	2,000,000
Common stock available for future grants, shares		7,000,000
Percentage of fair market value of stock at which employees are granted shares		85.00%
Number of shares purchased by employees, shares		1,000,000
Weighted-average purchase price, dollars per share | $ / shares		$ 69.60
Cash proceeds | $		$ 58
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock outstanding, shares		142,000,000	127,000,000
Common stock, votes per share | vote / shares		1
Class A Common Stock | 2012 Equity Incentive Plan (EIP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share reserve increased, shares	10,000,000
Common stock available for future grants, shares		61,000,000
Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock outstanding, shares		70,000,000	76,000,000
Common stock, votes per share | vote / shares		10
Percent of shares of common stock less than 9% of the outstanding shares		9.00%
Duration of time after death of Co-Founders until shares are converted, months		9 months
Restricted Stock Units (RSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, years		4 years
Weighted average grant date fair value (in dollars per share) | $ / shares		$ 88.90	$ 75.71	$ 85.29
Total grant-date fair value of units vested | $		$ 528	$ 303	$ 162
Unrecognized compensation cost | $		$ 957
Weighted-average period to be recognized, years		2 years 8 months 12 days
Number of shares granted, (in shares)		7,736,434
Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average period to be recognized, years		2 months
Unrecognized compensation cost | $		$ 7
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, years		5 years
Weighted-average period to be recognized, years		3 months
Unrecognized compensation cost | $		$ 0.1
Maximum exercise period, years		10 years
Fair value of options vested in period | $		$ 5	14	17
Total intrinsic value of the options exercised | $		$ 234	$ 273	$ 279
Weighted-average remaining contractual life of vested and expected to vest options, years		3 years 2 months
Weighted-average remaining contractual life of exercisable options, years		3 years 2 months
Weighted-average remaining contractual life of outstanding options, years		3 years 2 months
Vesting March 15 2017 | All Other Employees | Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted, (in shares)			300,000
Compensation cost | $		$ 6
Vesting March 15 2018 | All Other Employees | Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted, (in shares)		400,000
Compensation cost | $		$ 31

Common Stock and Stockholders80

Common Stock and Stockholders' Equity (Summary of Information Related to Restricted Stock Units Activity) (Detail) - Restricted Stock Units (RSU) - $ / shares	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Restricted Stock Units
Beginning Balance, Number of Shares	11,502,721
Restricted stock units granted, Number of Shares	7,736,434
Restricted stock units vested, Number of Shares	(5,412,921)
Restricted stock units forfeited, Number of Shares	(1,006,718)
Ending Balance, Number of Shares	12,819,516	11,502,721
Weighted-Average Grant Date Fair Value
Beginning Balance (in usd per share)	$ 78.45
Restricted stock units granted (in usd per share)	88.90	$ 75.71	$ 85.29
Restricted stock units vested (in usd per share)	78.26
Restricted stock units forfeited (in usd per share)	79.34
Ending Balance (in usd per share)	$ 84.77	$ 78.45

Common Stock and Stockholders81

Common Stock and Stockholders' Equity (Summary of Combined Activity Under 2005 Stock Plan and EIP) (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Jan. 31, 2018USD ($)$ / sharesshares
Outstanding Stock Options
Beginning Balance (in shares) | shares	9,096,592
Stock option grants (in shares) | shares	0
Stock options exercised (in shares) | shares	(2,490,931)
Stock options canceled (in shares) | shares	(10,175)
Ending Balance (in shares) | shares	6,595,486
Vested and expected to vest ( in shares) | shares	6,595,469
Exercisable (in shares) | shares	6,594,986
Weighted- Average Exercise Price
Beginning Balance (in usd per share) | $ / shares	$ 4.34
Stock option grants (in usd per share) | $ / shares	0
Stock options exercised (in usd per share) | $ / shares	4.60
Stock options canceled (in usd per share) | $ / shares	7.76
Ending Balance (in usd per share) | $ / shares	4.23
Vested and expected to vest, Weighted-Average Exercise Price (in usd per share) | $ / shares	4.23
Exercisable, Weighted-Average Exercise Price (in usd per share) | $ / shares	$ 4.23
Beginning Balance, Aggregate Intrinsic Value | $	$ 716
Ending Balance, Aggregate Intrinsic Value | $	763
Vested and expected to vest, Aggregate Intrinsic Value | $	763
Exercisable, Aggregate Intrinsic Value | $	$ 763

Common Stock and Stockholders82

Common Stock and Stockholders' Equity (Assumptions Used for Periods Presented) (Detail) - ESPP - $ / shares	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, Minimum	25.30%	34.50%	32.00%
Expected volatility, Maximum	32.00%	44.50%	34.20%
Expected term (in years)	6 months	6 months	6 months
Risk-free interest rate, Minimum	1.11%	0.53%	0.26%
Risk-free interest rate, Maximum	1.45%	0.91%	0.51%
Dividend yield, percentage	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value per share, dollars per share	$ 98.39	$ 69	$ 67.23
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value per share, dollars per share	$ 100.52	$ 79.30	$ 71.81

Unearned Revenue and Performa83

Unearned Revenue and Performance Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
Deferred revenue recognized	$ 1,000	$ 738
Remaining revenue expected to be recognized	$ 5,200
Recognition period for remaining performance obligations	24 months

Other Income (Expense), Net (De

Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Other Income and Expenses [Abstract]
Interest income	$ 25,252	$ 11,303		$ 4,855
Interest expense	(44,549)	(30,103)		(31,932)
Gain from sale of cost method investment	720	65	[1]	3,220	[1]
Impairment of cost method investment	(692)	(15,000)	[1]	0	[1]
Other income (expense)	7,706	1,308		(385)
Other income (expense), net	$ (11,563)	$ (32,427)	[1]	$ (24,242)	[1]
[1]	See Note 2 for a summary of adjustments.

Income Taxes (Components of Los

Income Taxes (Components of Loss before Provision for (Benefit from) Income Taxes) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (85,167)	$ (190,043)		$ (119,302)
Foreign	(229,619)	(195,470)		(154,729)
Loss before provision for (benefit from) income taxes	$ (314,786)	$ (385,513)	[1]	$ (274,031)	[1]
[1]	See Note 2 for a summary of adjustments.

Income Taxes (Summary of Provis

Income Taxes (Summary of Provision for (Benefit from) for Income Taxes) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Current:
Federal	$ 0	$ 213		$ (2,012)
State	177	17		489
Foreign	4,251	3,573		2,869
Total	4,428	3,803		1,346
Deferred:
Federal	(535)	(466)		0
State	(100)	(52)		0
Foreign	2,643	(4,099)		(329)
Total	2,008	(4,617)		(329)
Provision for (benefit from) income taxes	$ 6,436	$ (814)	[1]	$ 1,017	[1]
[1]	See Note 2 for a summary of adjustments.

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Taxes Computed at Federal Statutory Income Tax Rate and Provision for (Benefit from) Income Taxes) (Detail)	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Income Tax Disclosure [Abstract]
Federal statutory rate	33.80%	35.00%	35.00%
Effect of:
Foreign income at other than U.S. rates	(26.50%)	(18.50%)	(25.70%)
Intercompany transactions	10.20%	4.20%	5.20%
Research tax credits	9.10%	6.40%	5.10%
State taxes, net of federal benefit	0.00%	0.00%	(0.20%)
U.S. corporate tax rate reduction	(81.30%)	0.00%	0.00%
Changes in valuation allowance	33.00%	(20.40%)	(15.10%)
Stock compensation	20.00%	(6.10%)	(5.40%)
Other	(0.40%)	(0.40%)	0.70%
Total	(2.10%)	0.20%	(0.40%)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016	Feb. 01, 2017	Jan. 31, 2015
Tax Credit Carryforward [Line Items]
Federal statutory rate	33.80%	35.00%	35.00%
Income tax expense (benefit) of net deferred tax asset due to re-measurement	$ (256,000,000)
Deferred tax asset	702,481,000	$ 397,589,000
Valuation allowance	625,030,000	292,365,000
Increase of valuation allowance on net deferred tax assets	333,000,000	100,000,000
Unrecognized tax benefits, accrued penalties and interest	0	0
Unrecognized tax benefits	107,849,000	116,801,000	$ 98,460,000		$ 88,663,000
Unrecognized tax benefits that would impact effective tax rate	1,000,000
Federal
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	2,000,000,000
Federal | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	83,000,000
State
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	1,300,000,000
Foreign
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	25,000,000
California | State | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 87,000,000
Accounting Standards Update 2016-09
Tax Credit Carryforward [Line Items]
Deferred tax asset		$ 448,000,000
Valuation allowance				$ 447,800,000

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Deferred tax assets:
Unearned revenue	$ 27,934	$ 40,810
Other reserves and accruals	14,945	23,134
Federal net operating loss carryforwards	422,235	110,974
State and foreign net operating loss carryforwards	81,757	25,783
Property and equipment	0	24,754
Share-based compensation	39,294	70,642
Research and development credits	110,694	78,283
Other	5,622	23,209
Deferred tax asset	702,481	397,589
Valuation allowance	(625,030)	(292,365)
Deferred tax assets, net of valuation allowance	77,451	105,224
Deferred tax liabilities:
Intangibles	(1,453)	(3,742)
Intercompany transactions	(40,338)	(62,800)
Other prepaid assets	(742)	(1,079)
Deferred commissions	(29,231)	(33,267)
Property and equipment	(3,803)	0
Deferred tax liabilities	(75,567)	(100,888)
Net deferred tax assets	$ 1,884	$ 4,336

Income Taxes (Summary of Reconc

Income Taxes (Summary of Reconciliation of Gross Unrecognized Tax Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at the beginning of the period	$ 116,801	$ 98,460	$ 88,663
Additions for tax positions taken in prior years	1,500	3,981	2,818
Reductions for tax positions taken in prior years	(8,121)	0	(881)
Decrease for tax positions taken in prior years due to federal rate reduction	(10,062)	0	0
Additions for tax positions related to the current year	7,731	14,475	9,144
Reductions related to a lapse of applicable statute of limitations	0	(115)	(1,284)
Unrecognized tax benefits at the end of the period	$ 107,849	$ 116,801	$ 98,460

Net Loss Per Share (Summary of

Net Loss Per Share (Summary of Calculation of Basic and Diluted Net Loss Per Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Numerator:
Allocation of distributed net loss attributable to common stockholders									$ (321,222)	$ (384,699)	[1]	$ (275,048)	[1]
Denominator:
Weighted-average common shares outstanding (in shares)									207,774	198,214	[1]	190,016	[1]
Basic and diluted net loss per share (dollars per share)	$ (0.42)	$ (0.41)	$ (0.40)	$ (0.31)	$ (0.44)	$ (0.55)	$ (0.55)	$ (0.40)	$ (1.55)	$ (1.94)	[1]	$ (1.45)	[1]
Class A Common Stock
Numerator:
Allocation of distributed net loss attributable to common stockholders									$ (208,159)	$ (236,946)		$ (160,173)
Denominator:
Weighted-average common shares outstanding (in shares)									134,642	122,085		110,655
Basic and diluted net loss per share (dollars per share)									$ (1.55)	$ (1.94)		$ (1.45)
Class B Common Stock
Numerator:
Allocation of distributed net loss attributable to common stockholders									$ (113,063)	$ (147,753)		$ (114,875)
Denominator:
Weighted-average common shares outstanding (in shares)									73,132	76,129		79,361
Basic and diluted net loss per share (dollars per share)									$ (1.55)	$ (1.94)		$ (1.45)
[1]	See Note 2 for a summary of adjustments.

Net Loss Per Share (Summary o92

Net Loss Per Share (Summary of Diluted Net Loss Per Common Share) (Detail) - shares shares in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	50,428	36,369	38,202
Outstanding common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	6,595	9,097	12,863
Shares subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	0	110	621
Unvested restricted stock awards, units, and PRSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	13,209	12,155	9,851
Shares related to the convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	15,079	7,261	7,261
Shares subject to warrants related to the issuance of convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	15,079	7,261	7,261
Shares issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	466	485	345

Related-Party Transactions (Det

Related-Party Transactions (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Related Party Transaction [Line Items]
Lease term period, in years	95 years
Chairman, Mr. Duffield
Related Party Transaction [Line Items]
Lease term period, in years		9 years
Rent expense		$ 8	$ 8	$ 6

Geographic Information (Detail)

Geographic Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 582,480	$ 555,389	$ 525,320	$ 479,861	$ 439,584	$ 413,522	$ 373,657	$ 347,677	$ 2,143,050	$ 1,574,440	[1]	$ 1,156,690	[1]
Long-Lived Assets	546,609				365,877				546,609	365,877
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									1,694,347	1,283,475		966,250
Long-Lived Assets	479,996				321,442				479,996	321,442
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	52,904				35,720				52,904	35,720
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									448,703	290,965		$ 190,440
Long-Lived Assets	$ 13,709				$ 8,715				$ 13,709	$ 8,715
[1]	See Note 2 for a summary of adjustments.

401(k) Plan (Narrative) (Detail

401(k) Plan (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Retirement Benefits [Abstract]
Contributions by employer	$ 15	$ 6

Selected Quarterly Financial 96

Selected Quarterly Financial Data (unaudited) (Consolidated Statements of Operations Data) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018		Jan. 31, 2017	[1]	Jan. 31, 2016	[1]
Consolidated Statements of Operations Data:
Total revenues	$ 582,480	$ 555,389	$ 525,320	$ 479,861	$ 439,584	$ 413,522	$ 373,657	$ 347,677	$ 2,143,050		$ 1,574,440		$ 1,156,690
Operating loss	(81,335)	(80,059)	(81,629)	(60,200)	(88,939)	(105,932)	(86,685)	(71,530)	(303,223)		(353,086)		(249,789)
Net loss	$ (89,100)	$ (85,546)	$ (82,532)	$ (64,044)	$ (88,269)	$ (110,114)	$ (107,813)	$ (78,503)	$ (321,222)	[1]	$ (384,699)		$ (275,048)
Net loss per share, basic and diluted (dollars per share)	$ (0.42)	$ (0.41)	$ (0.40)	$ (0.31)	$ (0.44)	$ (0.55)	$ (0.55)	$ (0.40)	$ (1.55)		$ (1.94)		$ (1.45)
[1]	See Note 2 for a summary of adjustments.