Tableau Software 10-K 22 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Statement - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 19, 2019	Jun. 30, 2018
Document Information
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	TABLEAU SOFTWARE INC
Entity Central Index Key	1,303,652
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Well-Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Public Float			$ 5.6
Entity Shell Company	false
Common Class A
Document Information
Entity Common Stock, Shares Outstanding		75,594,200
Common Class B
Document Information
Entity Common Stock, Shares Outstanding		10,491,943

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 653,022	$ 627,878
Short-term investments	369,355	226,787
Accounts receivable, net	236,063	203,366
Prepaid expenses and other current assets	155,012	30,514
Income taxes receivable	2,268	673
Total current assets	1,415,720	1,089,218
Long-term investments	26,278	148,364
Property and equipment, net	94,537	106,753
Goodwill	42,530	35,083
Deferred income taxes	4,733	5,287
Other long-term assets	50,927	14,090
Total assets	1,634,725	1,398,795
Current liabilities
Accounts payable	6,652	4,448
Accrued compensation and employee-related benefits	105,155	96,390
Other accrued liabilities	55,896	37,722
Income taxes payable	2,982	4,743
Deferred revenue	377,892	419,426
Total current liabilities	548,577	562,729
Deferred revenue	16,306	28,058
Other long-term liabilities	56,257	54,385
Total liabilities	621,140	645,172
Commitments and contingencies (Note 11)
Stockholders' equity
Preferred stock	0	0
Common stock	8	8
Additional paid-in capital	1,340,628	1,168,563
Accumulated other comprehensive loss	(11,458)	(11,991)
Accumulated deficit	(315,593)	(402,957)
Total stockholders' equity	1,013,585	753,623
Total liabilities and stockholders' equity	1,634,725	1,398,795
Common Class B
Stockholders' equity
Common stock	1	1
Common Class A
Stockholders' equity
Common stock	$ 7	$ 7

Consolidated Balance Sheets - P

Consolidated Balance Sheets - Parenthetical - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Convertible Preferred Stock
Preferred stock par value (in USD per share)	$ 0.0001	$ 0.0001
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Class B
Common stock par value (in USD per share)	$ 0.0001	$ 0.0001
Shares authorized for issuance	75,000,000	75,000,000
Common Stock, Shares, Issued	11,042,131	14,492,846
Common Stock, Shares, Outstanding	11,042,131	14,492,846
Common Class A
Common stock par value (in USD per share)	$ 0.0001	$ 0.0001
Shares authorized for issuance	750,000,000	750,000,000
Common Stock, Shares, Issued	73,314,823	65,969,499
Common Stock, Shares, Outstanding	73,314,823	65,969,499

Consolidated Statement of Opera

Consolidated Statement of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Total revenues		$ 1,155,352	$ 877,059	$ 826,943
Cost of revenues
Total cost of revenues	[1]	142,624	113,559	99,090
Gross profit		1,012,728	763,500	727,853
Operating expenses
Sales and marketing	[1]	593,786	517,446	476,506
Research and development	[1]	382,886	334,148	302,759
General and administrative	[1]	125,805	102,871	88,149
Total operating expenses		1,102,477	954,465	867,414
Operating loss		(89,749)	(190,965)	(139,561)
Other income, net		17,872	12,266	2,134
Loss before income tax expense		(71,877)	(178,699)	(137,427)
Income tax expense		5,165	6,861	7,022
Net loss		$ (77,042)	$ (185,560)	$ (144,449)
Net loss per share:
Basic		$ (0.93)	$ (2.35)	$ (1.92)
Diluted		$ (0.93)	$ (2.35)	$ (1.92)
Weighted average shares used to compute net loss per share:
Basic		82,632	78,869	75,162
Diluted		82,632	78,869	75,162
License
Revenues
Total revenues		$ 555,581	$ 429,204	$ 481,659
Cost of revenues
Total cost of revenues		21,407	13,534	7,003
Maintenance and services
Revenues
Total revenues		599,771	447,855	345,284
Cost of revenues
Total cost of revenues		$ 121,217	$ 100,025	$ 92,087
[1]	Includes stock-based compensation expense as follows: Year Ended December 31, 2018 2017 2016 (in thousands)Cost of revenues$13,392 $11,029 $10,595Sales and marketing87,105 74,065 68,411Research and development111,965 104,280 91,044General and administrative26,269 20,909 15,662

Consolidated Statement of Ope_2

Consolidated Statement of Operations - Parenthetical - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cost of revenues
Stock-based compensation expense	$ 13,392	$ 11,029	$ 10,595
Sales and marketing
Stock-based compensation expense	87,105	74,065	68,411
Research and development
Stock-based compensation expense	111,965	104,280	91,044
General and administrative
Stock-based compensation expense	$ 26,269	$ 20,909	$ 15,662

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss Statement - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ 2,833	$ (21,337)	$ (12,066)	$ (46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	$ (77,042)	$ (185,560)	$ (144,449)
Other comprehensive income (loss), net of tax:
Foreign currency translation									(937)	(12,920)	950
Net unrealized loss on available-for-sale securities									(213)	(664)	0
Comprehensive loss									$ (78,192)	$ (199,144)	$ (143,499)

Consolidated Statements of Shar

Consolidated Statements of Shareholders Equity Statement - USD ($) $ in Thousands	Total	Common Stock (Class A and B)	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances (in shares), period start at Dec. 31, 2015		73,204,464
Balances, period start at Dec. 31, 2015	$ 733,945	$ 7	$ 805,804	$ 643	$ (72,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock		3,960,475
Issuance of common stock	$ 34,357	$ 1	34,356
Repurchase of common stock (in shares)	(446,517)
Repurchase of common stock	$ (20,009)		(20,009)
Stock-based compensation expense	185,712		185,712
Excess tax benefit from stock-based compensation	1,342		1,342
Other comprehensive loss, net	950			950
Net loss	(144,449)				(144,449)
Balances (in shares), period end at Dec. 31, 2016		76,718,422
Balances, period end at Dec. 31, 2016	791,848	$ 8	1,007,205	1,593	(216,958)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock		5,008,351
Issuance of common stock	$ 38,856	$ 0	38,856
Repurchase of common stock (in shares)	(1,264,428)
Repurchase of common stock	$ (79,991)		(79,991)
Stock-based compensation expense	202,054		202,054
Other comprehensive loss, net	(13,584)			(13,584)
Net loss	(185,560)				(185,560)
Balances (in shares), period end at Dec. 31, 2017		80,462,345
Balances, period end at Dec. 31, 2017	753,623	$ 8	1,168,563	(11,991)	(402,957)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock		5,115,205
Issuance of common stock	$ 44,710	$ 0	44,710
Repurchase of common stock (in shares)	(1,220,596)
Repurchase of common stock	$ (120,024)		(120,024)
Stock-based compensation expense	247,379		247,379
Other comprehensive loss, net	(1,150)			(1,150)
Net loss	(77,042)				(77,042)
Balances (in shares), period end at Dec. 31, 2018		84,356,954
Balances, period end at Dec. 31, 2018	$ 1,013,585	$ 8	$ 1,340,628	$ (11,458)	$ (315,593)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (77,042)	$ (185,560)	$ (144,449)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization expense	35,787	44,746	43,006
Amortization (accretion) on investments, net	(424)	359	0
Stock-based compensation expense	238,731	210,283	185,712
Deferred income taxes	(2,180)	(2,988)	1,219
Changes in operating assets and liabilities
Accounts receivable, net	(36,519)	12,493	(78,197)
Prepaid expenses and other assets	(95,347)	8,054	(18,987)
Income taxes receivable	(1,675)	(515)	(56)
Deferred revenue	56,555	123,938	116,860
Accounts payable and accrued liabilities	38,396	13,529	71,157
Income taxes payable	(1,586)	2,528	997
Net cash provided by operating activities	154,696	226,867	177,262
Investing activities
Purchases of property and equipment	(20,446)	(61,823)	(60,732)
Business combinations, net of cash acquired	(10,947)	(23,966)	(16,399)
Purchases of investments	(285,277)	(421,719)	0
Maturities of investments	262,835	30,630	0
Sales of investments	2,171	14,916	0
Net cash used in investing activities	(51,664)	(461,962)	(77,131)
Financing activities
Proceeds from issuance of common stock	44,710	38,856	34,356
Repurchases of common stock	(120,024)	(79,991)	(20,009)
Net cash provided by (used in) financing activities	(75,314)	(41,135)	14,347
Effect of exchange rate changes on cash and cash equivalents	(2,574)	(4,609)	(1,661)
Net increase (decrease) in cash and cash equivalents	25,144	(280,839)	112,817
Cash and cash equivalents
Beginning of year	627,878	908,717	795,900
End of year	653,022	627,878	908,717
Supplemental disclosures
Cash paid for income taxes	5,819	4,347	1,513
Non-cash activities
Accrued purchases of property and equipment	$ 7,885	$ 6,470	$ 26,548

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Tableau Software, Inc., a Delaware corporation, and its wholly-owned subsidiaries (the "Company", "we", "us" or "our") are headquartered in Seattle, Washington. Our software products put the power of data into the hands of everyday people, allowing a broad population of business users to engage with their data, ask questions, solve problems and create value. Based on innovative core technologies originally developed at Stanford University, our products dramatically reduce the complexity, inflexibility and expense associated with traditional business intelligence applications. We currently offer five key products: Tableau Desktop, a self-service, powerful analytics product for anyone with data; Tableau Server, a business intelligence platform for organizations; Tableau Online, a hosted software-as-a-service ("SaaS") version of Tableau Server; Tableau Prep, a data preparation product for combining, shaping and cleaning data; and Tableau Public, a free cloud-based platform for analyzing and sharing public data.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Accounting Principles The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States ("GAAP"). We adopted the new revenue recognition accounting standard, codified as Accounting Standards Codification (“ASC”) 606, effective January 1, 2018 on a modified retrospective basis (see Recently Adopted Accounting Pronouncements ). Financial results for reporting periods during 2018 are presented in compliance with the new revenue recognition standard. Historical financial results for reporting periods prior to 2018 are presented in conformity with amounts previously disclosed under the prior revenue recognition standard, ASC 605. These financial statements include additional information regarding the impacts from the adoption of the new revenue recognition standard on our financial results for the year ended December 31, 2018. This includes the presentation of financial results for the year ended December 31, 2018 under ASC 605 for comparison to the prior year. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates include but are not limited to: the collectability of our receivables; the evaluation of our contract assets for impairment; the useful lives of our property and equipment and other lease-related assets, liabilities and costs; the benefit period for deferred commissions; the valuation of investments and the determination of other-than-temporary impairments; and the reported amounts of accrued liabilities. For revenue, we make estimates and assumptions related to the standalone selling prices of our products and services and the nature and timing of the delivery of performance obligations from our contracts with customers. We also use estimates in stock-based compensation, income taxes and business combinations. Actual results could differ from those estimates. Foreign Currency The financial statements of our foreign subsidiaries with a functional currency other than U.S. dollars have been translated into U.S. dollars. Assets and liabilities of these subsidiaries are translated at the exchange rate in effect at each period-end. Income statement amounts are translated at the average rate of exchange prevailing during the period. Translation adjustments arising from the use of differing exchange rates from period to period are included in other comprehensive income (loss). As of December 31, 2018 and 2017 , we had a cumulative translation loss of $(10.6) million and $(11.3) million , respectively. Gains and losses on foreign currency transactions are included in other income, net. Foreign currency transaction gains (losses) were $(0.5) million , $4.1 million and $(0.6) million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Risks and Uncertainties Inherent in our business are various risks and uncertainties, including our limited history of operating our business at its current scale and development of advanced technologies in a rapidly changing industry. These risks include our ability to manage our growth, to attract new customers, to expand sales to existing customers and to attract, integrate and retain qualified personnel, as well as other risks and uncertainties. In the event that we do not successfully implement our business plan, certain assets may not be recoverable, certain liabilities may not be paid and investments in our capital stock may not be recoverable. Our success depends upon the acceptance of our technology, development of sales and distribution channels and our ability to generate significant revenues from the sale of our technology. Segments We follow the authoritative literature that established annual and interim reporting standards for an enterprise's operating segments and related disclosures about its products and services, geographic regions and major customers. We operate our business as one operating segment. Our chief operating decision makers ("CODM") are our Chief Executive Officer and Chief Financial Officer, who review financial information presented on a consolidated basis for purposes of making operating decisions, assessing financial performance and allocating resources. Revenue Recognition - ASC 606 We generate revenues primarily in the form of software license fees and related maintenance and services fees. Software license revenues include fees from the sales of perpetual, term and subscription licenses. Maintenance and services revenues primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements if and when they are available), training and professional services. We recognize revenues related to contracts with customers that meet the following criteria: • the contract contains reasonable evidence of approval and of both parties' commitment to perform their respective obligations; • the contract includes identifiable rights to goods and/or services to be transferred and payment terms related to the transfer of those goods and/or services; • the contract has commercial substance; and • collection of substantially all of the consideration we are entitled to under the contract is probable. We identify performance obligations in our contracts with customers, which may include software licenses and/or related maintenance and services. We determine the transaction price based on the amount of consideration we expect to receive in exchange for transferring the promised goods or services to the customer. We allocate the transaction price in the contract to each distinct performance obligation in an amount that depicts the relative amount of consideration we expect to receive in exchange for satisfying each performance obligation. Revenue is recognized when performance obligations are satisfied. Our contract payment terms are typically net 30 days . We assess collectability based on a number of factors including collection history and creditworthiness of the customer, and we may mitigate exposures to credit risk by requiring payments in advance. If we determine that collectability related to a contract is not probable, we may not record revenue until collectability becomes probable at a later date. Our revenues are recorded based on the transaction price excluding amounts collected on behalf of third parties. For example, indirect taxes which we collect and remit to governmental authorities are excluded from our revenues. Nature of Products and Services Our on-premises software licenses are sold through both perpetual and term-based license agreements. These licensing arrangements provide customers with the same product functionality and differ mainly in the duration over which the customer benefits from the software. We deliver our software licenses electronically. Electronic delivery occurs when we provide the customer with access to the software and license key via a secure portal. Revenue from on-premises software licenses is generally recognized upfront at the point in time when the software is made available to the customer. Our contracts with customers for on-premises software licenses include maintenance services and may also include training and/or professional services. Maintenance services agreements consist of fees for providing software updates on an if and when available basis and for providing technical support for software products for a specified term. We believe that our software updates and technical support each have the same pattern of transfer to the customer and are substantially the same. Therefore, we consider these updates and technical support to be a single distinct performance obligation. Revenues allocated to maintenance services are recognized ratably as the maintenance services are provided. Revenues related to training services are billed on a fixed fee basis and are recognized as the services are delivered. Payments received in advance of services performed are deferred and recognized when the related services are performed. Revenues related to professional services are billed on a time and materials basis and are recognized as the services are performed. We also provide cloud-based subscriptions, which allow customers to access our software during a contractual period without taking possession of the software. We recognize revenue related to these cloud-based subscriptions ratably over the life of the subscription agreement beginning when the customer first has access to the software. Revenues from our cloud-based subscriptions are included in license revenues. Judgments and Estimates Our contracts with customers often include promises to transfer multiple products and services. Determining whether products and services are considered distinct performance obligations that should be accounted for separately from one another sometimes requires judgment. Judgment is also required to determine standalone selling prices (“SSP”s) for each distinct performance obligation. We typically have more than one SSP for each of our products and services based on customer stratification, which is based on the size of the customer, their geographic region and market segment. For perpetual software licenses, we estimate SSPs by considering our pricing objectives and discounting practices. For our cloud-based subscriptions and for maintenance services, training and professional services, SSPs are generally observable using standalone sales and/or renewals. Our on-premises term-based software licenses generally do not have directly observable inputs for determining SSP. Therefore, we determine SSP using other observable inputs including customer-buying patterns, renewal rates and cumulative spend comparisons. We evaluate contracts with customers that include options to purchase additional goods or services to determine whether the options give rise to a separate performance obligation that is material. If we determine the options give rise to a separate performance obligation that is material, the revenue allocated to such options is not recognized until the option is exercised or the option expires. Assets Recognized from the Costs to Obtain a Contract with a Customer We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We have determined that certain costs related to our sales incentive programs meet the requirements to be capitalized and deferred. Assets recorded are included in prepaid expenses and other current assets and other long-term assets. We amortize these deferred costs proportionate with related revenues over the benefit period, currently estimated to be four years. We consider the benefit period to exceed the initial contract term for certain costs because of anticipated renewals and because our sales commission rates for renewal contracts are not commensurate with sales commissions for initial contracts. Prior to our adoption of the new revenue recognition standard, we recognized sales commissions expense as incurred. Contract Assets Contract assets represent the portion of the transaction price from a contract with a customer where control has transferred, but for which we currently do not have the contractual right to invoice. These assets, included within prepaid expenses and other current assets, are also subject to impairment risk. We reduce our gross contract asset balance for any impairments identified based on our consideration of a combination of factors including past collection experience, credit quality of the customer, age of other receivables balances due from the customer and current economic conditions. Revenue Recognition - ASC 605 Our revenue recognition accounting policy for ASC 605 is shown below. We applied the revenue recognition accounting policy for ASC 605 to our disclosures in Note 8, which include amounts presented for 2018. We generate revenues primarily in the form of software license fees and related maintenance and services fees. Software license fees include fees from the sales of perpetual, term and subscription licenses. Maintenance and services fees primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements when and if they are available), training and professional services that are not essential to the functionality of the software. We recognize revenues when all of the following conditions are met: • there is persuasive evidence of an arrangement; • the software or services have been delivered to the customer; • the amount of fees to be paid by the customer is fixed or determinable; and • the collection of the related fees is probable. We use click-through license agreements, signed agreements and purchase orders as evidence of an arrangement. We deliver all of our software electronically. Electronic delivery occurs when we provide the customer with access to the software and license key via a secure portal. We assess whether the fee is fixed or determinable at the outset of the arrangement. Our typical terms of payment are due 30 days from delivery. We assess collectability based on a number of factors such as collection history and creditworthiness of the customer. If we determine that collectability is not probable, revenue is deferred until collectability becomes probable, generally upon receipt of cash. Substantially all of our software licenses are sold in multiple-element arrangements that include maintenance services and may include professional services and training. Vendor specific objective evidence ("VSOE") of the fair value for software licenses is not available as our software licenses are never sold without maintenance; however, VSOE generally exists for all undelivered elements and any services that are not essential to the functionality of the delivered software. Therefore, we account for delivered software licenses under the residual method. Maintenance agreements consist of fees for providing software updates on a when and if available basis and technical support for software products ("post-contract support" or "PCS") for an initial term, generally one year. We have established VSOE of the fair value for maintenance on perpetual licenses based on stated substantive renewal rates or the price when sold on a standalone basis. Stated renewal rates are considered to be substantive if they are at least 15% of the actual price charged for the software license. VSOE of the fair value for standalone maintenance contracts is considered to have been established when a substantial majority of individual sales transactions within the previous 12 months falls within a reasonably narrow range, which we have defined to be plus or minus 15% of the median sales price of actual standalone sales transactions. License arrangements may include professional services and training. In determining whether professional services and training revenues should be accounted for separately from license revenues, we evaluate: • whether such services are considered essential to the functionality of the software using factors such as the nature of the software products; • whether they are ready for use by the customer upon receipt; • the nature of the services, which typically do not involve significant customization to or development of the underlying software code; • the availability of services from other vendors; • whether the timing of payments for license revenues coincides with performance of services; and • whether milestones or acceptance criteria exist that affect the realizability of the software license fee. To date, professional services have not been considered essential to the functionality of the software. The VSOE of the fair value of our professional services and training is based on the price for these same services when they are sold separately. Revenues related to professional services are billed on a time and materials basis and are recognized as the services are performed. Revenues related to training services are billed on a fixed fee basis and are recognized as the services are delivered. Payments received in advance of services performed are deferred and recognized when the related services are performed. When software is licensed for a specified term or on a subscription basis, fees for maintenance and support are generally bundled with the license fee over the entire term of the contract. In these cases, we do not have VSOE of the fair value for maintenance and support. Revenues related to term and subscription license fees are recognized ratably over the contract term beginning on the date the customer has access to the software license key and continuing through the end of the contract term. We do not offer refunds and therefore have not recorded any sales return allowance for any of the periods presented. Upon a periodic review of outstanding accounts receivable, amounts that are deemed to be uncollectable are written off against the allowance for doubtful accounts. We account for taxes collected from customers and remitted to governmental authorities on a net basis and exclude them from revenues. Cash and Cash Equivalents We consider all highly liquid investments purchased with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents are recorded at fair value. We maintain cash and cash equivalent balances which exceed the insured limits by the Federal Deposit Insurance Corporation. Investments We classify our investment securities as available-for-sale. Our investment securities are stated at fair value and reported in short-term investments and long-term investments. Investments in securities with maturities of less than one year, or where management's intent is to use the investments to fund current operations, are classified as short-term investments. Investments with maturities greater than one year are classified as long-term investments. Unrealized gains and losses on available-for-sale securities are excluded from net income and reported, net of tax, in other comprehensive income (loss). Realized gains and losses and declines in the value of securities judged to be other-than-temporary are determined based on the specific identification method and are included in other income, net. In order to determine whether a decline in value is other-than-temporary, we evaluate, among other factors, our intent and ability to recover the amortized cost basis of the security. Interest on securities classified as available-for-sale is included in other income, net. Accounts Receivable, Net Accounts receivable consist of amounts billed and currently due from customers. Our accounts receivable are subject to collection risk. Our gross accounts receivable is reduced for this risk by a provision for doubtful accounts. This provision is for estimated losses resulting from the inability of our customers to make required payments. It is an estimate and is regularly evaluated for adequacy by taking into consideration a combination of factors. We look at factors such as past collection experience, credit quality of the customer, age of the receivable balance and current economic conditions. These factors are reviewed to determine whether a provision for doubtful accounts should be recorded to reduce the receivable balance to the amount believed to be collectible. Activity related to our provision for doubtful accounts was as follows: Year Ended December 31, 2018 2017 2016 (in thousands) Balance at the beginning of the year $ 1,003 $ 1,065 $ 888 Bad debt expense 1,168 650 750 Accounts written off (563 ) (712 ) (573 ) Balance at the end of the year $ 1,608 $ 1,003 $ 1,065 Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives range from approximately one to twelve years. Leasehold improvements are depreciated over the shorter of the estimated useful life or the remaining lease term. When assets are retired or disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gains or losses are included in results of operations. Maintenance and repairs that do not improve or extend the lives of the respective assets are charged to expense in the period incurred. Business Combinations As of the date of an acquisition, we recognize the identifiable assets acquired and liabilities assumed at fair value. Intangible assets acquired are measured at their acquisition date fair value using valuation techniques that are subject to judgment. Any excess of the consideration over the fair value of identifiable net assets is recorded as goodwill. Amounts that are not part of the consideration transferred are recognized separately from a business combination and are expensed as incurred. Goodwill and Intangible Assets Intangible assets with a finite life are typically amortized over their useful lives which range from three to five years. Goodwill is tested for impairment on an annual basis in the third quarter and more frequently if circumstances indicate that the carrying value may not be recoverable. As part of our goodwill impairment test, we first perform a qualitative assessment to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying amount. For purposes of this assessment, we consider the enterprise to be the reporting unit. If we determine it is more likely than not that the fair value of our reporting unit is less than its carrying amount, we will perform a quantitative assessment to determine whether the fair value of our reporting unit is less than its carrying amount. We have not had any impairments of the goodwill balance. Leases Leases are categorized at their inception as either operating or capital leases. Within some lease agreements, rent holidays and other incentives are included. Rent expense is recognized using the straight-line method over the term of the agreement, which generally begins once control of the space is obtained. Any cash incentives received are treated as a reduction of expense over the term of the agreement. Impairment of Long-Lived Assets Property and equipment, intangible assets with a finite life and other long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Recoverability of an asset to be held and used is tested by comparing the carrying amount of the asset to the estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. No impairment of long-lived assets occurred in the periods presented. Software Development Costs Software development costs associated with the development of new products, enhancements of existing products and quality assurance activities consist of employee, consulting and other external personnel costs. The costs incurred internally from the research and development ("R&D") of computer software products are charged to expense until technological feasibility has been established for the product. Once technological feasibility is established, all software costs are capitalized until the product is available for release to customers. Judgment is required in determining when technological feasibility of a product is established. To date, we have determined that technological feasibility of software products is reached shortly before the products are released. Costs incurred after establishment of technological feasibility have not been material, and therefore, we have expensed all R&D costs as they were incurred. R&D expenses primarily consist of personnel-related costs attributable to our R&D personnel and allocated overhead, which includes facilities-related costs. We capitalize certain costs relating to software developed or modified solely to meet our internal requirements and for which there are no substantive plans to market the software. To date, we have not capitalized any such costs as these costs have not been material. Intangible Asset Costs Costs related to filing and pursuing patent and trademark applications are expensed as incurred, as recoverability of such expenditures is uncertain. These intangible asset-related legal costs are generally reported as a component of general and administrative expenses. Advertising Expenses We expense all advertising costs as incurred and classify such costs as sales and marketing expenses. Advertising expenses for the years ended December 31, 2018 , 2017 and 2016 were $36.5 million , $28.2 million and $21.7 million , respectively. Income Taxes Income taxes are accounted for under the asset and liability method in accordance with authoritative guidance for income taxes. Deferred income tax assets are recognized for deductible temporary differences, net operating loss carryforwards, and tax credit carryforwards if it is more likely than not that the tax benefits will be realized. We consider future taxable income, historical operating results and ongoing prudent and feasible tax planning strategies in assessing the need for a valuation allowance. A valuation allowance is recorded to reduce our deferred income tax assets to the net amount that we believe is more likely than not to be realized. In the event we determine that we are able to realize our deferred income tax assets in excess of our net recorded amount, we would reduce the valuation allowance associated with the deferred income tax assets in the period the determination is made, which may result in a tax benefit in the statement of operations. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Our assumptions, judgments and estimates relative to the value of net deferred income taxes take into account predictions of the amount and category of future taxable income, such as income from operations or capital gains income. Actual operating results and the underlying amount and category of income in future years could render our current assumptions, judgments and estimates of recoverable net deferred income taxes inaccurate. Any of the assumptions, judgments and estimates mentioned above could cause our actual income tax obligations to differ from our estimates, thus materially impacting our financial position and results of operations. Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents, investments, accounts receivable and contract assets. Our investment portfolio consists of investment-grade securities diversified among security types, industries and issuers. Our cash and cash equivalents and investments are held and managed by recognized financial institutions that follow our investment policy. Our policy limits the amount of credit exposure to any one security issue or issuer. We extend credit to customers based upon an evaluation of the customer's financial condition. As of December 31, 2018 and 2017 , no individual customer accounted for 10% or more of total accounts receivable. As of December 31, 2018 , no individual customer accounted for 10% or more of total contract assets. For the years ended December 31, 2018 , 2017 and 2016 , no individual customer represented 10% or more of our total revenues. Fair Value Measurements We categorize assets and liabilities recorded at fair value on our consolidated balance sheets based upon the level of judgment associated with inputs used to measure their fair value. The levels of the fair value hierarchy are as follows: • Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. • Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3—Inputs are unobservable inputs based on our own assumptions and valuation techniques used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. We establish fair value of our assets and liabilities using the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date and using a fair value hierarchy based on the inputs used to measure fair value. The carrying amounts reported in the consolidated financial statements approximate the fair value for accounts receivable, accounts payable, and accrued and other current liabilities, due to their short-term nature. We value our cash equivalents and investments using quoted prices for identical instruments in active markets when available. If we are unable to obtain quoted prices for identical instruments in active markets, we value our cash equivalents and investments using quoted market prices for comparable instruments. To date, all of our cash equivalents and investments have been valued using one of these two methodologies. Stock-Based Compensation We record compensation expense for stock-based transactions including employee and non-employee stock option and restricted stock unit ("RSU") awards granted under our 2004 Equity Incentive Plan (the "2004 Plan") and our 2013 Equity Incentive Plan, as amended, (the "2013 Plan" and together with the 2004 Plan, the "Plans"). We also record compensation expense related to employee contributions made under our 2013 Employee Stock Purchase Plan ("2013 ESPP"). These contributions are used to purchase shares of our Class A common stock at a discount. Stock-based compensation expense is measured and recognized in the financial statements based on fair value. The fair value of each RSU award is determined based on the closing price of our Class A common stock as reported on the New York Stock Exchange on the date of grant. The fair value of each stock option award is determined at the date of grant by applying the Black-Scholes option pricing model. We also use the Black-Scholes option pricing model to determine the fair value of each common share issued under the 2013 ESPP. The fair value for 2013 ESPP grants is determined on the first day of each offering period. The Black-Scholes option pricing model utilizes the value of our underlying common stock at the measurement date, the expected or contractual term of the option or offering period, the expected volatility of our common stock, risk-free interest rates and expected dividend yield of our common stock. Prior to our initial public offering ("IPO") in May 2013, the fair value of our common stock was determined by our board of directors. After the completion of our IPO, our common stock has been valued by reference to the closing price of our Class A common stock as reported on the New York Stock Exchange. We recognize stock-based compensation expense using the straight-line method over the requisite service period. We account for forfeitures as they occur. For awards subject to technology milestones, we recognize compensation cost over the requisite service period if it is probable that the technology milestone will be met. If our assessment

Balance Sheet Detail

Balance Sheet Detail	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Detail	Balance Sheet Detail Property and Equipment, Net Property and equipment, net consisted of the following: Useful Life December 31, (in months) 2018 2017 (in thousands) Computer equipment and software 36 $ 93,671 $ 98,737 Furniture and fixtures 36 26,914 25,232 Leasehold improvements 12-150 86,082 85,482 Construction in progress 10,693 313 217,360 209,764 Less: Accumulated depreciation (122,823 ) (103,011 ) $ 94,537 $ 106,753 Depreciation and amortization expense on our property and equipment and lease-related assets was $34.0 million , $43.9 million and $42.7 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Intangible Assets The only changes to the carrying amount of intangible assets during 2018 were an increase of $3.5 million related to our acquisition of Empirical Systems, Inc. (Note 7), and amortization expense. Amortization expense on our intangible assets was $1.8 million , $0.8 million and $0.3 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Intangible assets are included within other long-term assets. Goodwill The only change to the carrying amount of goodwill during 2018 was an increase of $7.4 million related to our acquisition of Empirical Systems, Inc. (Note 7). Accrued Compensation and Employee-Related Benefits Accrued compensation and employee-related benefits consisted of the following: December 31, 2018 2017 (in thousands) Accrued commissions $ 33,820 $ 31,333 Accrued bonuses 34,767 25,435 Accrued vacation 17,375 14,512 Other 19,193 25,110 Total $ 105,155 $ 96,390

Short-Term and Long-Term Invest

Short-Term and Long-Term Investments Short-Term and Long-Term Investments	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Short-term and Long-term Investments Disclosure	Short-Term and Long-Term Investments The following tables present our short-term and long-term investments in available-for-sale securities based on remaining contractual years to maturity: December 31, 2018 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) Short-term investments Commercial paper $ 7,949 $ — $ — $ 7,949 U.S. treasury securities 206,486 24 (457 ) 206,053 U.S. agency securities 18,576 — (61 ) 18,515 Corporate bonds 137,119 — (281 ) 136,838 Total short-term investments 370,130 24 (799 ) 369,355 Long-term investments U.S. treasury securities 13,352 5 (50 ) 13,307 Corporate bonds 13,025 2 (56 ) 12,971 Total long-term investments 26,377 7 (106 ) 26,278 Total short-term and long-term investments $ 396,507 $ 31 $ (905 ) $ 395,633 December 31, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) Short-term investments Commercial paper $ 9,970 $ — $ — $ 9,970 U.S. treasury securities 160,206 — (121 ) 160,085 U.S. agency securities 9,917 — (24 ) 9,893 Corporate bonds 46,901 3 (65 ) 46,839 Total short-term investments 226,994 3 (210 ) 226,787 Long-term investments U.S. treasury securities 79,371 — (202 ) 79,169 U.S. agency securities 18,570 — (102 ) 18,468 Corporate bonds 50,880 — (153 ) 50,727 Total long-term investments 148,821 — (457 ) 148,364 Total short-term and long-term investments $ 375,815 $ 3 $ (667 ) $ 375,151 The following table presents the fair values and the gross unrealized losses related to our investments in available-for-sale securities that were in an unrealized loss position as of December 31, 2018 , summarized by the length of time that the investments have been in a continuous unrealized loss position: December 31, 2018 Less Than 12 Months 12 Months or Greater Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (in thousands) Short-term investments U.S. treasury securities $ 89,320 $ (143 ) $ 79,472 $ (314 ) $ 168,792 $ (457 ) U.S. agency securities — — 18,515 (61 ) 18,515 (61 ) Corporate bonds 91,455 (131 ) 45,383 (150 ) 136,838 (281 ) Total short-term investments 180,775 (274 ) 143,370 (525 ) 324,145 (799 ) Long-term investments U.S. treasury securities 9,855 (50 ) — — 9,855 (50 ) Corporate bonds 11,389 (56 ) — — 11,389 (56 ) Total long-term investments 21,244 (106 ) — — 21,244 (106 ) Total short-term and long-term investments $ 202,019 $ (380 ) $ 143,370 $ (525 ) $ 345,389 $ (905 ) The unrealized losses on investments as of December 31, 2018 were primarily caused by increases in interest rates. None of the unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of December 31, 2018 . As of December 31, 2017 , there were no investments that had been in a continuous unrealized loss position for 12 months or greater. We earn interest on our cash equivalents and investments balances. For the years ended December 31, 2018 , 2017 and 2016 , we earned interest income of $17.0 million , $8.5 million and $2.7 million , respectively.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following tables present the fair value of our financial assets using the fair value hierarchy: December 31, 2018 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents Money market funds $ 610,732 $ — $ — $ 610,732 Corporate bonds — 3,009 — 3,009 Short-term investments Commercial paper — 7,949 — 7,949 U.S. treasury securities — 206,053 — 206,053 U.S. agency securities — 18,515 — 18,515 Corporate bonds — 136,838 — 136,838 Long-term investments U.S. treasury securities — 13,307 — 13,307 Corporate bonds — 12,971 — 12,971 Total $ 610,732 $ 398,642 $ — $ 1,009,374 December 31, 2017 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents Money market funds $ 582,835 $ — $ — $ 582,835 Commercial paper — 8,984 — 8,984 Short-term investments Commercial paper — 9,970 — 9,970 U.S. treasury securities — 160,085 — 160,085 U.S. agency securities — 9,893 — 9,893 Corporate bonds — 46,839 — 46,839 Long-term investments U.S. treasury securities — 79,169 — 79,169 U.S. agency securities — 18,468 — 18,468 Corporate bonds — 50,727 50,727 Total $ 582,835 $ 384,135 $ — $ 966,970 We did not have any investments in prime money market funds as of December 31, 2018 or 2017 . We did not have any material financial assets or liabilities measured using Level 3 inputs as of December 31, 2018 or 2017 .

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combinations	Business Combinations Empirical Systems, Inc. On June 7, 2018, we acquired all issued and outstanding stock of Empirical Systems, Inc., a privately-held Delaware corporation, for $11.0 million in cash. Empirical Systems, Inc. was a startup specializing in automated statistical analysis. As a result of this acquisition, we acquired all of the assets and assumed all of the liabilities of Empirical Systems, Inc., and we accounted for this transaction as a business combination. Pro forma results of operations for this acquisition have not been presented as the effects were not material to our financial results. The following table summarizes the purchase price allocation based on the estimated fair value of the net assets acquired: June 7, 2018 (in thousands) Cash $ 53 Technology asset 3,500 Goodwill 7,447 Net assets acquired $ 11,000 The technology asset acquired in this business combination is being amortized on the straight-line method over a period of five years. Goodwill generated from this business combination is primarily attributable to expected synergies between the technology asset acquired and our key products. None of the goodwill recognized with this transaction is expected to be deductible for U.S. income tax purposes. Certain employees hired in conjunction with the acquisition of Empirical Systems, Inc. received RSUs that are subject to service conditions as well as the completion of certain technology milestones. We account for these awards as a post-business combination expense. Additional information existing as of the acquisition date but unknown to us may become known at a later time, such as matters related to income taxes or other contingencies. In accordance with GAAP, if this occurs during the 12 month period subsequent to the acquisition date, we may update the amounts and allocations recorded as of the acquisition date, which are presented in the table above. Argo Technologies Corp. On August 1, 2017, we acquired all issued and outstanding stock of Argo Technologies Corp., a privately-held Delaware corporation doing business as ClearGraph ("ClearGraph"), for $24.1 million in cash. ClearGraph was a startup that enables smart data discovery and data analysis through natural language query technology. As a result of this acquisition, we acquired all of the assets and assumed all of the liabilities of ClearGraph, and we accounted for this transaction as a business combination. Pro forma results of operations for this acquisition were not presented as the effects were not material to our financial results. The following table summarizes the purchase price allocation based on the estimated fair value of the net assets acquired: August 1, 2017 (in thousands) Cash $ 161 Technology asset 5,000 Goodwill 19,552 Other liabilities, net (586 ) Net assets acquired $ 24,127 The technology asset acquired in this business combination is being amortized on the straight-line method over a period of five years. Goodwill generated from this business combination was primarily attributable to expected synergies between the technology asset acquired and our key products. None of the goodwill recognized with this transaction is expected to be deductible for U.S. income tax purposes. Hyper On March 1, 2016, we acquired Hyper, a high-performance main-memory database system, for $16.4 million in cash. Through this acquisition we acquired new technology, capable of enhancing our key products, and additional engineering talent. We accounted for this transaction as a business combination, and allocated $1.8 million to the acquired technology intangible asset. The remaining purchase price was recorded to goodwill, which was primarily attributable to the synergies between Hyper and our key products. No other assets or liabilities were identified as part of the acquisition. A portion of the goodwill balance associated with this transaction is deductible for U.S. income tax purposes. Pro forma results of operations for this acquisition were not presented as the effects were not material to our consolidated financial results.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Common Stock Our certificate of incorporation, as amended and restated, authorizes us to issue 75,000,000 shares of Class B common stock, at $0.0001 par value per share, and 750,000,000 shares of Class A common stock, at $0.0001 par value per share. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each holder of Class B common stock is entitled to ten votes per share and each holder of Class A common stock is entitled to one vote per share. Shares of Class B common stock may be converted into Class A common stock at any time at the option of the stockholder, and are automatically converted upon sale or transfer, to Class A common stock, subject to certain limited exceptions. At its discretion, the board of directors may declare dividends on shares of common stock, subject to the rights of our preferred stockholders, if any. Upon liquidation or dissolution, holders of common stock will receive distributions only after preferred stock preferences have been satisfied. Preferred Stock Our certificate of incorporation, as amended and restated, authorizes us to issue 10,000,000 shares of preferred stock at $0.0001 par value per share. Our board of directors has the authority to provide for the issuance of all the shares in one or more series. At its discretion, our board of directors may designate the voting rights and preferences of the preferred stock. As of December 31, 2018 and 2017 , no shares of preferred stock were outstanding. Stock Repurchase Program On November 1, 2016, we announced that our board of directors approved a stock repurchase program, under which we were authorized to repurchase up to $200 million of our outstanding Class A common stock. On April 26, 2018, our board of directors authorized us to repurchase up to an additional $300 million of our outstanding Class A common stock under our previously announced stock repurchase program. The repurchase program has no expiration date and may be modified, suspended or discontinued at any time. Repurchases under the program may be made from time to time on the open market at prevailing market prices, in privately negotiated transactions, in transactions structured through investment banking institutions or a combination of the foregoing, in compliance with Rule 10b-18 under the Securities Exchange Act of 1934, as amended. During the year ended December 31, 2018 , we repurchased 1,220,596 shares of our outstanding Class A common stock at an average price of $98.33 per share for $120.0 million . During the year ended December 31, 2017 , we repurchased 1,264,428 shares of our outstanding Class A common stock at an average price of $63.26 per share for $80.0 million . All repurchases were made in open market transactions using cash on hand and all of the shares repurchased were retired. As of December 31, 2018 , we were authorized to repurchase a remaining $280.0 million of our Class A common stock under our repurchase program.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue We adopted the new revenue recognition accounting standard, ASC 606, effective January 1, 2018 on a modified retrospective basis and applied the new standard only to contracts that were not completed contracts prior to January 1, 2018. See Note 2 for a description of our ASC 606 revenue recognition accounting policy. Financial results for 2018 are presented in compliance with the new revenue recognition standard. Historical financial results for reporting periods prior to 2018 have not been retroactively restated and are presented in conformity with amounts previously disclosed under ASC 605. This note includes additional information regarding the impacts from the adoption of the new revenue recognition standard on our financial results for 2018 . This includes the presentation of financial results for 2018 under ASC 605 for comparison to the prior year. Our revenue recognition accounting policy for ASC 605 is included in Note 2. Consolidated Balance Sheets - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated balance sheet: December 31, 2018 December 31, 2017 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) (in thousands) Assets Current assets Cash and cash equivalents $ 653,022 $ — $ 653,022 $ 627,878 Short-term investments 369,355 — 369,355 226,787 Accounts receivable, net 236,063 — 236,063 203,366 Prepaid expenses and other current assets 155,012 (121,418 ) 33,594 30,514 Income taxes receivable 2,268 97 2,365 673 Total current assets 1,415,720 (121,321 ) 1,294,399 1,089,218 Long-term investments 26,278 — 26,278 148,364 Property and equipment, net 94,537 — 94,537 106,753 Goodwill 42,530 — 42,530 35,083 Deferred income taxes 4,733 3,170 7,903 5,287 Other long-term assets 50,927 (34,871 ) 16,056 14,090 Total assets $ 1,634,725 $ (153,022 ) $ 1,481,703 $ 1,398,795 Liabilities and stockholders' equity Current liabilities Accounts payable $ 6,652 $ — $ 6,652 $ 4,448 Accrued compensation and employee-related benefits 105,155 — 105,155 96,390 Other accrued liabilities 55,896 — 55,896 37,722 Income taxes payable 2,982 (46 ) 2,936 4,743 Deferred revenue 377,892 199,210 577,102 419,426 Total current liabilities 548,577 199,164 747,741 562,729 Deferred revenue 16,306 12,232 28,538 28,058 Other long-term liabilities 56,257 (1,718 ) 54,539 54,385 Total liabilities 621,140 209,678 830,818 645,172 Stockholders' equity Common stock 8 — 8 8 Additional paid-in capital 1,340,628 — 1,340,628 1,168,563 Accumulated other comprehensive loss (11,458 ) 1,902 (9,556 ) (11,991 ) Accumulated deficit (315,593 ) (364,602 ) (680,195 ) (402,957 ) Total stockholders' equity 1,013,585 (362,700 ) 650,885 753,623 Total liabilities and stockholders' equity $ 1,634,725 $ (153,022 ) $ 1,481,703 $ 1,398,795 Consolidated Statements of Operations - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of operations: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Revenues License $ 555,581 $ (57,531 ) $ 498,050 $ 429,204 $ 481,659 Maintenance and services 599,771 (114,872 ) 484,899 447,855 345,284 Total revenues 1,155,352 (172,403 ) 982,949 877,059 826,943 Cost of revenues License 21,407 (484 ) 20,923 13,534 7,003 Maintenance and services 121,217 514 121,731 100,025 92,087 Total cost of revenues 142,624 30 142,654 113,559 99,090 Gross profit 1,012,728 (172,433 ) 840,295 763,500 727,853 Operating expenses Sales and marketing 593,786 26,768 620,554 517,446 476,506 Research and development 382,886 — 382,886 334,148 302,759 General and administrative 125,805 (119 ) 125,686 102,871 88,149 Total operating expenses 1,102,477 26,649 1,129,126 954,465 867,414 Operating loss (89,749 ) (199,082 ) (288,831 ) (190,965 ) (139,561 ) Other income, net 17,872 (46 ) 17,826 12,266 2,134 Loss before income tax expense (71,877 ) (199,128 ) (271,005 ) (178,699 ) (137,427 ) Income tax expense 5,165 1,068 6,233 6,861 7,022 Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Consolidated Statements of Comprehensive Loss - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of comprehensive loss: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Other comprehensive income (loss), net of tax: Foreign currency translation (937 ) 3,585 2,648 (12,920 ) 950 Net unrealized loss on available-for-sale securities (213 ) — (213 ) (664 ) — Comprehensive loss $ (78,192 ) $ (196,611 ) $ (274,803 ) $ (199,144 ) $ (143,499 ) Consolidated Statements of Cash Flows - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of cash flows: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Operating activities Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Adjustments to reconcile net loss to net cash provided by operating activities Depreciation and amortization expense 35,787 — 35,787 44,746 43,006 Amortization (accretion) on investments, net (424 ) — (424 ) 359 — Stock-based compensation expense 238,731 — 238,731 210,283 185,712 Deferred income taxes (2,180 ) 942 (1,238 ) (2,988 ) 1,219 Changes in operating assets and liabilities Accounts receivable, net (36,519 ) — (36,519 ) 12,493 (78,197 ) Prepaid expenses and other assets (95,347 ) 91,351 (3,996 ) 8,054 (18,987 ) Income taxes receivable (1,675 ) (99 ) (1,774 ) (515 ) (56 ) Deferred revenue 56,555 108,141 164,696 123,938 116,860 Accounts payable and accrued liabilities 38,396 — 38,396 13,529 71,157 Income taxes payable (1,586 ) (49 ) (1,635 ) 2,528 997 Net cash provided by operating activities 154,696 90 154,786 226,867 177,262 Investing activities Purchases of property and equipment (20,446 ) — (20,446 ) (61,823 ) (60,732 ) Business combinations, net of cash acquired (10,947 ) — (10,947 ) (23,966 ) (16,399 ) Purchases of investments (285,277 ) — (285,277 ) (421,719 ) — Maturities of investments 262,835 — 262,835 30,630 — Sales of investments 2,171 — 2,171 14,916 — Net cash used in investing activities (51,664 ) — (51,664 ) (461,962 ) (77,131 ) Financing activities Proceeds from issuance of common stock 44,710 — 44,710 38,856 34,356 Repurchases of common stock (120,024 ) — (120,024 ) (79,991 ) (20,009 ) Net cash provided by (used in) financing activities (75,314 ) — (75,314 ) (41,135 ) 14,347 Effect of exchange rate changes on cash and cash equivalents (2,574 ) (90 ) (2,664 ) (4,609 ) (1,661 ) Net increase (decrease) in cash and cash equivalents 25,144 — 25,144 (280,839 ) 112,817 Cash and cash equivalents Beginning of year 627,878 — 627,878 908,717 795,900 End of year $ 653,022 $ — $ 653,022 $ 627,878 $ 908,717 Disclosures Related to our Contracts with Customers Timing may differ between the satisfaction of performance obligations and the invoicing and collection of amounts related to our contracts with customers. We record assets for amounts related to performance obligations that are satisfied but not yet billed and/or collected. These assets are recorded as contract assets rather than receivables when receipt of the consideration is conditional on something other than the passage of time. Liabilities are recorded for amounts that are collected in advance of the satisfaction of performance obligations. These liabilities are classified as current and non-current deferred revenue. Contract Assets and Contract Liabilities The following table presents the activity impacting our contract assets during the year ended December 31, 2018 : Contract Assets (in thousands) Balance at December 31, 2017 $ — Adoption of ASC 606 40,854 Contract assets transferred to receivables (37,698 ) Additions to contract assets 102,437 Balance at December 31, 2018 $ 105,593 Contract assets are included in prepaid expenses and other current assets. There were no material impairments of contract assets during the year ended December 31, 2018 . The following table presents the activity impacting our deferred revenue balances during the year ended December 31, 2018 : Deferred Revenue (in thousands) Balance at December 31, 2017 $ 447,484 Adoption of ASC 606 (105,933 ) Deferred revenue recognized (314,765 ) Additional amounts deferred 367,412 Balance at December 31, 2018 $ 394,198 Assets Recognized from the Costs to Obtain our Contracts with Customers We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We amortize these deferred costs proportionate with related revenues over the benefit period, currently estimated to be four years. The following table presents the activity impacting our deferred contract costs during the year ended December 31, 2018 : Deferred Contract Costs (in thousands) Balance at December 31, 2017 $ — Adoption of ASC 606 25,489 Additional contract costs deferred 37,528 Amortization of deferred contract costs (11,616 ) Balance at December 31, 2018 $ 51,401 As of December 31, 2018 , $16.5 million of our deferred contract costs are expected to be amortized within the next 12 months and therefore are included in prepaid expenses and other current assets. The remaining amount of our deferred contract costs are included in other long-term assets. There were no material impairments of assets related to deferred contract costs during the year ended December 31, 2018 . There were no assets recognized related to the costs to fulfill contracts during the year ended December 31, 2018 as these costs were not material. Remaining Performance Obligations Our contracts with customers include amounts allocated to performance obligations that will be satisfied at a later date. As of December 31, 2018 , amounts allocated to these additional contractual obligations are $240.1 million , of which we expect to recognize $191.7 million as revenue over the next 24 months with the remaining amount thereafter. These amounts include additional performance obligations that are not yet recorded in the consolidated balance sheets.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Our 2004 Plan authorized the granting of options to purchase shares of our Class B common stock, RSUs and other stock-based awards to our employees, consultants, officers and directors. Our 2013 Plan, which is the successor to our 2004 Plan, authorizes the granting of options to purchase shares of our Class A common stock, RSUs and other stock-based awards to our employees, consultants, officers and directors. Options granted under the Plans may be incentive or nonstatutory stock options. Incentive stock options may only be granted to employees. The term of each option is stated in the award agreement, but shall be no more than ten years from the date of grant. The board of directors determines the period over which options and RSUs become vested. Currently, the vesting period for our options and RSUs is typically four years. Our 2013 ESPP allows eligible employees to purchase shares of our Class A common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to plan limitations. The 2013 ESPP currently includes purchase periods approximately six months in duration starting on the first trading date on or after June 1 st and December 1 st of each year. Participants are able to purchase shares of our common stock at 85% of the lower of its fair market value on (i) the first day of the purchase period or on (ii) the purchase date, which is the last day of the purchase period. A summary of the option activity during the year ended December 31, 2018 follows: Options Outstanding Shares Weighted Average Exercise Price per Share Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Balances at December 31, 2017 3,017,113 $ 10.13 Options exercised (1,097,730 ) 9.60 Balances at December 31, 2018 1,919,383 $ 10.44 3.12 $ 210,283 Vested and expected to vest at December 31, 2018 1,919,383 $ 10.44 3.12 $ 210,283 Exercisable at December 31, 2018 1,886,570 $ 9.67 3.04 $ 208,146 The stock options are exercisable at a price equal to the market value of the underlying shares of common stock on the date of the grant. For options granted prior to the IPO this value was determined by our board of directors. After the IPO, this value was determined by reference to the closing price of our Class A common stock on the New York Stock Exchange on the date of the grant. The total intrinsic value of options exercised during 2018 , 2017 and 2016 was $92.4 million , $74.5 million and $63.3 million , respectively. The intrinsic value is the difference between the fair value of our Class A common stock and the exercise price of each of the respective stock options. The total grant date fair value of options vested during 2018 , 2017 and 2016 was $0.4 million , $1.2 million and $7.8 million , respectively. A summary of the RSU activity, including RSU awards subject to technology milestones, during the year ended December 31, 2018 follows: Number of Shares Underlying Outstanding RSUs Weighted-Average Grant-Date Fair Value per RSU Non-Vested outstanding at December 31, 2017 7,178,015 $ 62.79 RSUs granted 4,374,326 92.25 RSUs vested (3,526,004 ) 67.74 RSUs forfeited (831,883 ) 68.16 Non-Vested outstanding at December 31, 2018 7,194,454 $ 77.66 An RSU award entitles the holder to receive shares of our Class A common stock as the award vests, which is generally based on length of service. Our non-vested RSUs do not have nonforfeitable rights to dividends or dividend equivalents. Stock-based compensation expense is recognized using the straight-line method over the requisite service period. We account for forfeitures as they occur. For RSU awards subject to technology milestones, we recognize compensation cost over the estimated requisite service period if we believe it is probable that the associated technology milestone will be met. If our assessment of the probability of the technology milestone being met changes, we recognize the impact of the change in estimate in the period of the change. The weighted-average grant date fair value of RSUs granted in 2018 , 2017 and 2016 was $92.25 , $60.62 and $44.61 , respectively. The total intrinsic value of RSUs vested during 2018 , 2017 and 2016 was $342.3 million , $185.7 million and $92.5 million , respectively. As of December 31, 2018 , total unrecognized compensation expense related to stock options and non-vested RSUs was $502.4 million , which is expected to be recognized over a weighted-average period of 2.8 years . The summary of shares available for issuance of equity-based awards (including stock options, RSUs and shares issuable under our 2013 ESPP) during the year ended December 31, 2018 follows: Shares Available for Grant 2013 Plan 2013 ESPP Balances at December 31, 2017 7,207,291 3,666,392 Authorized 4,023,117 804,623 Granted (4,374,326 ) (491,471 ) Forfeited 831,883 — Balances at December 31, 2018 7,687,965 3,979,544 Pursuant to the provisions of our 2013 Plan, the number of shares authorized for issuance increases annually on January 1 st by the lesser of 5% of the total number of shares of our capital stock outstanding on December 31 st of the preceding calendar year or an amount determined by our board of directors. Pursuant to the provisions of our 2013 ESPP, the number of shares authorized for issuance increases annually on January 1 st by the lesser of 1% of the total number of shares of our capital stock outstanding on December 31 st of the preceding calendar year, 4,000,000 shares of Class A common stock, or an amount determined by our board of directors. There are no shares available for grant under our 2004 plan. Valuation Assumptions Stock-based awards granted to our employees, consultants, officers and directors are measured based on the grant date fair value of the awards. For the years ended December 31, 2018 and 2017, there were no options granted. The weighted average grant date fair value of stock options granted for the year ended December 31, 2016 was $23.73 . For the year ended December 31, 2016, the fair value of options was estimated using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2016 Risk-free interest rates 1.2% Expected term 5.2 years Expected dividends None Expected volatility 48.0% There were 491,471 , 604,177 and 549,327 Class A common stock shares issued under the 2013 ESPP for the years ended December 31, 2018 , 2017 and 2016 , respectively. For the years ended December 31, 2018 , 2017 and 2016 , the fair value of common share purchase rights under the 2013 ESPP was estimated using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2018 2017 2016 Risk-free interest rates 2.1% - 2.5% 1.1% - 1.5% 0.5% - 0.6% Expected term 0.5 years 0.5 years 0.5 years Expected dividends None None None Expected volatility 28.7% - 44.5% 28.6% - 30.5% 42.0% - 50.1% The risk-free interest rates are based on the rates for a U.S. Treasury zero-coupon issue with a term that approximates the expected life of the award. The expected term represents the period that our stock-based awards are expected to be outstanding. For awards of stock options, the expected term approximates the expected life of the awards at the date closest to the grant date, determined based on actual experience adjusted for expected employee exercise behavior. For shares expected to be issued under our 2013 ESPP, the expected term is based on the duration of each purchase period, which is approximately six months. We have not paid and do not expect to pay dividends. We estimate expected future volatility based on the annualized daily historical volatility of our stock price.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of our loss before income tax expense consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States $ (44,488 ) $ (134,723 ) $ (100,725 ) International (27,389 ) (43,976 ) (36,702 ) Total $ (71,877 ) $ (178,699 ) $ (137,427 ) Income tax expense (benefit) consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States $ (108 ) $ (592 ) $ 2,147 International 5,273 7,453 4,875 Total $ 5,165 $ 6,861 $ 7,022 The provision for income taxes consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Current: Federal $ — $ — $ 1,447 State 197 233 402 Foreign 9,425 10,704 5,230 Total current income tax expense 9,622 10,937 7,079 Deferred: Federal (241 ) (892 ) 258 State (64 ) 67 40 Foreign (4,152 ) (3,251 ) (355 ) Total deferred income tax benefit (4,457 ) (4,076 ) (57 ) Total income tax expense $ 5,165 $ 6,861 $ 7,022 A reconciliation of the U.S. federal statutory income tax provision (benefit) (computed by multiplying the U.S. federal statutory rate of 21% in 2018 and 35% in both 2017 and 2016 by loss before income tax expense) to the effective income tax expense for each year follows: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Income tax benefit at statutory rate $ (15,094 ) $ (62,545 ) $ (48,098 ) State taxes, net of federal tax benefit (1,835 ) (4,714 ) (3,466 ) Impact of foreign income taxes 12,239 23,232 14,566 Impact of Tax Cuts and Jobs Act of 2017 3,367 87,584 — Research and development and other tax credits (17,933 ) (12,563 ) (8,462 ) Stock-based compensation (35,858 ) (13,466 ) 5,098 Non-deductible meals and entertainment expenses 2,313 1,182 1,212 Impact of valuation allowance 57,284 (13,598 ) 46,174 Other, net 682 1,749 (2 ) Total income tax expense $ 5,165 $ 6,861 $ 7,022 Our effective tax rate differs from the U.S. federal statutory rate primarily due to the impact of the valuation allowance on our U.S. federal and state deferred income tax assets and losses in jurisdictions where a tax benefit is not available. Our effective tax rates in 2018 and 2017 were also impacted by excess tax benefits from stock-based compensation, which are recognized as an income tax benefit due to our adoption of ASU 2016-09 in 2017. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “Act”) was signed with an effective date of January 1, 2018. The Act, which significantly revised U.S. tax law, included many important changes. On the same day, Staff Accounting Bulletin No. 118 ("SAB 118") was issued to assist in addressing uncertainty in applying GAAP to the accounting and reporting of tax reform changes related to the Act. We considered these changes, including all available guidance, in determining our income tax provision for the year ended December 31, 2017. As permitted by SAB 118, we have subsequently finalized our accounting analysis based on the guidance, interpretations and data available as of December 31, 2018 and recorded the adjustments in the fourth quarter of 2018. On January 22, 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income (“GILTI”) provisions of the Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The Company elects to recognize any potential GILTI as an expense in the period the tax is incurred. The tax effects of temporary differences and carryforwards that gave rise to deferred income tax assets and liabilities consisted of the following: December 31, 2018 2017 As Reported (ASC 606) As Reported (ASC 605) (in thousands) Deferred income tax assets: Net operating loss carryforwards $ 154,409 $ 133,187 Tax credit carryforwards 73,020 59,343 Stock-based compensation 12,612 15,512 Accrued compensation 13,803 11,487 Deferred revenue 4,120 5,334 Deferred rent 12,065 12,483 Depreciation and amortization 34,350 966 Other 1,766 1,149 Total deferred income tax assets 306,145 239,461 Deferred income tax liabilities: Prepaid assets 3,011 4,177 Deferred commissions 12,676 — Total deferred income tax liabilities 15,687 4,177 Net deferred income tax assets before valuation allowance 290,458 235,284 Less: valuation allowance (287,935 ) (230,545 ) Net deferred income tax assets $ 2,523 $ 4,739 Reported as: Deferred income taxes 4,733 5,287 Other long-term liabilities (2,210 ) (548 ) Net deferred income tax assets $ 2,523 $ 4,739 We determine our deferred income tax assets and liabilities based on differences between the financial reporting and tax basis of assets and liabilities using the enacted tax rates and laws that will be in effect when we expect the differences to reverse . We regularly assess the need for a valuation allowance against our deferred income tax assets by considering both positive and negative evidence related to whether it is more likely than not that our deferred income tax assets will be realized. A valuation allowance is recorded when it is more likely than not that all or some portion of the deferred income tax assets will not be realized. In evaluating our ability to recover our deferred income tax assets within the jurisdiction from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred income tax liabilities, projected future taxable income, tax-planning strategies and results of recent operations. In 2015, we established a valuation allowance of $46.7 million for our U.S. federal and state deferred income tax assets, in part due to our three-year cumulative GAAP net loss adjusted for permanent tax differences, which is a significant piece of negative evidence for recording the valuation allowance. Through the year ended December 31, 2017, we increased the valuation allowance to $230.5 million . In 2018, we determined our U.S. federal and state deferred income tax assets continue to be currently not more likely than not to be realized; therefore, we increased the valuation allowance to $287.9 million as of December 31, 2018 . The increase in the valuation allowance during 2018 was primarily attributable to the current year change in U.S. federal and state deferred income tax assets. We have gross net operating loss carryforwards totaling $999.7 million , R&D tax credit carryforwards of $93.3 million and Federal foreign tax credits of $4.6 million . If not utilized, the R&D tax credit carryforwards and net operating loss carryforwards will begin to expire in 2034. Utilization of our net operating loss and tax credit carryforwards may be subject to limitations upon certain ownership changes as provided by the Internal Revenue Code and similar state provisions. We are subject to income taxes in the U.S. and in numerous foreign jurisdictions. The statute of limitations for adjustments to our historic tax obligations will vary from jurisdiction to jurisdiction. Furthermore, net operating loss and tax credit carryforwards may be subject to adjustment after the expiration of the statute of limitations for the year such net operating losses and tax credits originated. In general, the tax years for U.S. federal and state income tax purposes open for examination are for 2013 and forward due to our net operating loss carryforwards. Income tax expense includes both U.S. and international income taxes. Except as required under U.S. tax law, we do not provide for U.S. income taxes on our undistributed earnings of foreign subsidiaries that have not been previously taxed because we intend to invest such undistributed earnings indefinitely outside of the U.S. As of December 31, 2018 , cash held by foreign subsidiaries was $35.9 million . We have reserves for taxes to address potential exposures involving tax positions that we believe could be challenged by taxing authorities even though we believe the positions we have taken are appropriate. We believe our tax reserves are adequate to cover potential liabilities. We review the tax reserves as circumstances warrant and adjust the reserves as events occur that affect our potential liability for additional taxes. It is often difficult to predict the final outcome or timing of resolution of any particular tax matter. Various events, some of which cannot be predicted, such as clarification of tax law by administrative or judicial means, may occur and would require us to increase or decrease our reserves and effective income tax rate. Total gross unrecognized tax benefits were $28.1 million , $19.9 million and $12.9 million as of December 31, 2018 , 2017 and 2016 , respectively. Of these amounts, the portion recorded as liabilities pertaining to uncertain tax positions was $3.1 million , $1.4 million and $0.7 million as of December 31, 2018 , 2017 and 2016 , respectively. Our increase in unrecognized tax benefits relates primarily to the R&D tax credits generated in the current year, which are recorded net of the corresponding deferred tax asset. These amounts represent the gross amount of exposure in individual jurisdictions and do not reflect any additional benefits expected to be realized if such positions were not sustained. To the extent that any uncertain tax positions are resolved in our favor, it may have a positive impact on our effective income tax rate. We do not expect any material decrease on our unrecognized tax position within the next twelve months. The following table shows the gross changes in our unrecognized tax position. Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Balance, beginning of year $ 19,881 $ 12,909 $ 10,781 Gross increases to tax positions related to prior periods 1,174 1,289 28 Gross decreases to tax positions related to prior periods (291 ) — — Gross increases related to current tax positions 7,377 5,683 2,100 Balance, end of year $ 28,141 $ 19,881 $ 12,909 Interest or penalties, if incurred, would be recognized as a component of income tax expense. Penalties and interest recognized were not material for the years ended December 31, 2018 , 2017 and 2016 . On July 27, 2015, the U.S. Tax Court issued an opinion related to litigation in Altera Corp v. Commissioner. This litigation relates to the treatment of stock-based compensation expense in an intercompany cost sharing arrangement with one of Altera's foreign subsidiaries. In its opinion, the U.S. Tax Court invalidated the portion of the Treasury regulations requiring the inclusion of stock-based compensation expense in such intercompany cost-sharing arrangements. On February 19, 2016, the IRS appealed the U.S. Tax Court's decision. On July 24, 2018, the Ninth Circuit Court of Appeals issued a decision that was subsequently withdrawn and assigned to a new panel to consider the appeal. As the final resolution of this litigation remains uncertain, we have not recorded potentially favorable benefits related to the current or prior periods. We will continue to monitor developments related to this case and the potential impact of those developments on our current and future financial statements.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Lease Commitments and Expected Sublease Receipts We conduct our operations in facilities leased for non-cancellable periods that expire at various dates through 2030 . Many of our lease agreements contain extension options for additional periods. We recognize rent expense on the straight-line method over the defined lease periods. Total rent expense under operating leases, net of sublease income, was approximately $34.7 million , $41.1 million and $44.1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The following table presents our non-cancellable future minimum lease payments, net of future sublease receipts expected to be received under non-cancellable subleases, as of December 31, 2018 : Year Ending December 31, Operating Lease Commitments Expected Sublease Receipts Net (in thousands) 2019 $ 44,569 $ (9,912 ) $ 34,657 2020 45,835 (8,125 ) 37,710 2021 46,562 (1,208 ) 45,354 2022 45,858 (625 ) 45,233 2023 46,789 (128 ) 46,661 Thereafter 136,829 — 136,829 Total $ 366,442 $ (19,998 ) $ 346,444 Contractual Commitments Our contractual commitments are associated with agreements that are enforceable and legally binding and that specify all significant terms, including fixed or minimum services to be used, fixed, minimum or variable price provisions and the approximate timing of the transaction. Obligations under contracts that we can cancel without a significant penalty are not included. The following table presents our non-lease contractual commitments as of December 31, 2018 : Payments Due by Year Total 2019 2020 2021 2022 2023 Thereafter (in thousands) Contractual commitments $ 42,631 $ 24,295 $ 10,947 $ 7,193 $ 168 $ 28 $ — Legal Proceedings We are subject to certain routine legal proceedings, as well as demands and claims that arise in the normal course of our 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 and adjusted to reflect the impacts of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. We are not aware of any pending legal proceedings that we believe, individually or in the aggregate, would be expected to have a material adverse effect on our business, operating results or financial condition. We may, in the future, be party to litigation arising in the ordinary course of business, including claims that we allegedly infringe upon third party intellectual property rights. Such claims, even if not meritorious, could result in the expenditure of significant financial and management resources.

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Retirement Plan	Retirement Plan We offer a salary deferral 401(k) plan for our U.S. employees. The plan allows employees to contribute a percentage of their pretax earnings annually, subject to limitations imposed by the IRS. The plan also allows us to make matching contributions, subject to certain limitations. We contributed $7.5 million , $3.7 million and $3.6 million to the 401(k) plan for the years ended December 31, 2018 , 2017 and 2016 , respectively.

Segments and Information about

Segments and Information about Revenues by Geographic Region	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segments and Information about Revenues by Geographic Area	Segments and Information about Revenues by Geographic Area The following table presents our revenues by geographic region of end users who purchased products or services for the periods presented below: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States and Canada $ 797,874 $ 683,073 $ 605,773 $ 586,494 International 357,478 299,876 271,286 240,449 Total revenues $ 1,155,352 $ 982,949 $ 877,059 $ 826,943 For the years ended December 31, 2018 , 2017 and 2016 , no individual country other than the United States represented 10% or more of our total revenues. Substantially all of our long-lived assets were located in the United States as of December 31, 2018 and 2017 .

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Loss Per Share We calculate basic net income (loss) per share by dividing our net income (loss) for the period by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed giving effect to all potential common shares that were dilutive and outstanding during the period. For the years ended December 31, 2018 , 2017 and 2016 , basic net loss per share is the same as diluted net loss per share as the inclusion of all potentially dilutive common shares outstanding is anti-dilutive when we are in a net loss position. The following table presents the computation of basic and diluted net loss per share and includes additional information regarding the impacts from the adoption of the new revenue recognition standard for the year ended December 31, 2018: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands, except per share data) Net loss per share - basic and diluted Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Weighted average shares outstanding used to compute basic and diluted net loss per share 82,632 82,632 78,869 75,162 Net loss per share - basic and diluted $ (0.93 ) $ (3.36 ) $ (2.35 ) $ (1.92 ) The following shares were excluded from the computation of diluted net loss per share for the periods presented as their effect would have been antidilutive: Year Ended December 31, 2018 2017 2016 (in thousands) Shares subject to outstanding common stock awards 9,237 10,488 12,017

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) The following table contains selected unaudited financial data for each quarter of 2018 and 2017 . The unaudited information should be read in conjunction with our financial statements and these notes to the consolidated financial statements. We believe that the following unaudited information reflects all normal recurring adjustments necessary for a fair presentation of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. Three Months Ended Dec 31, 2018 Sept 30, 2018 June 30, 2018 March 31, 2018 Dec 31, 2018 Sept 30, 2018 June 30, 2018 March 31, 2018 As Reported (ASC 606) Without Adoption (ASC 605) (in thousands, except per share amounts) Total revenues $ 336,276 $ 290,580 $ 282,289 $ 246,207 $ 275,748 $ 239,591 $ 243,566 $ 224,044 Gross profit 296,081 255,801 247,064 213,782 235,574 204,785 208,326 191,610 Net income (loss) 2,833 (21,337 ) (12,066 ) (46,472 ) (67,348 ) (71,297 ) (59,567 ) (79,026 ) Net income (loss) per share: Basic $ 0.03 $ (0.26 ) $ (0.15 ) $ (0.57 ) $ (0.80 ) $ (0.86 ) $ (0.72 ) $ (0.98 ) Diluted $ 0.03 $ (0.26 ) $ (0.15 ) $ (0.57 ) $ (0.80 ) $ (0.86 ) $ (0.72 ) $ (0.98 ) Three Months Ended Dec 31, 2017 Sept 30, 2017 June 30, 2017 March 31, 2017 As Reported (ASC 605) (in thousands, except per share amounts) Total revenues $ 249,356 $ 214,917 $ 212,880 $ 199,906 Gross profit 219,046 184,988 186,215 173,251 Net loss (41,838 ) (46,553 ) (42,522 ) (54,647 ) Net loss per share: Basic and diluted $ (0.52 ) $ (0.59 ) $ (0.54 ) $ (0.71 )

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 3, 2019, we donated 209,384 shares of our Class A common stock to Tableau Foundation, a donor-advised charitable fund. We will record a charge of $24.2 million to general and administrative expense in the first quarter of 2019 based on the value of our stock on the date of contribution. In the first quarter of 2019, we entered into additional lease agreements for office facilities resulting in $21.7 million of additional future minimum lease payments payable from 2019 through 2030.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Accounting Principles	Accounting Principles The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States ("GAAP"). We adopted the new revenue recognition accounting standard, codified as Accounting Standards Codification (“ASC”) 606, effective January 1, 2018 on a modified retrospective basis (see Recently Adopted Accounting Pronouncements ). Financial results for reporting periods during 2018 are presented in compliance with the new revenue recognition standard. Historical financial results for reporting periods prior to 2018 are presented in conformity with amounts previously disclosed under the prior revenue recognition standard, ASC 605. These financial statements include additional information regarding the impacts from the adoption of the new revenue recognition standard on our financial results for the year ended December 31, 2018. This includes the presentation of financial results for the year ended December 31, 2018 under ASC 605 for comparison to the prior year.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates include but are not limited to: the collectability of our receivables; the evaluation of our contract assets for impairment; the useful lives of our property and equipment and other lease-related assets, liabilities and costs; the benefit period for deferred commissions; the valuation of investments and the determination of other-than-temporary impairments; and the reported amounts of accrued liabilities. For revenue, we make estimates and assumptions related to the standalone selling prices of our products and services and the nature and timing of the delivery of performance obligations from our contracts with customers. We also use estimates in stock-based compensation, income taxes and business combinations. Actual results could differ from those estimates.
Foreign Currency	Foreign Currency The financial statements of our foreign subsidiaries with a functional currency other than U.S. dollars have been translated into U.S. dollars. Assets and liabilities of these subsidiaries are translated at the exchange rate in effect at each period-end. Income statement amounts are translated at the average rate of exchange prevailing during the period. Translation adjustments arising from the use of differing exchange rates from period to period are included in other comprehensive income (loss). As of December 31, 2018 and 2017 , we had a cumulative translation loss of $(10.6) million and $(11.3) million , respectively. Gains and losses on foreign currency transactions are included in other income, net. Foreign currency transaction gains (losses) were $(0.5) million , $4.1 million and $(0.6) million for the years ended December 31, 2018 , 2017 and 2016 , respectively.
Risks and Uncertainties	Risks and Uncertainties Inherent in our business are various risks and uncertainties, including our limited history of operating our business at its current scale and development of advanced technologies in a rapidly changing industry. These risks include our ability to manage our growth, to attract new customers, to expand sales to existing customers and to attract, integrate and retain qualified personnel, as well as other risks and uncertainties. In the event that we do not successfully implement our business plan, certain assets may not be recoverable, certain liabilities may not be paid and investments in our capital stock may not be recoverable. Our success depends upon the acceptance of our technology, development of sales and distribution channels and our ability to generate significant revenues from the sale of our technology.
Segments	Segments We follow the authoritative literature that established annual and interim reporting standards for an enterprise's operating segments and related disclosures about its products and services, geographic regions and major customers. We operate our business as one operating segment. Our chief operating decision makers ("CODM") are our Chief Executive Officer and Chief Financial Officer, who review financial information presented on a consolidated basis for purposes of making operating decisions, assessing financial performance and allocating resources.
Revenue Recognition	Revenue Recognition - ASC 606 We generate revenues primarily in the form of software license fees and related maintenance and services fees. Software license revenues include fees from the sales of perpetual, term and subscription licenses. Maintenance and services revenues primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements if and when they are available), training and professional services. We recognize revenues related to contracts with customers that meet the following criteria: • the contract contains reasonable evidence of approval and of both parties' commitment to perform their respective obligations; • the contract includes identifiable rights to goods and/or services to be transferred and payment terms related to the transfer of those goods and/or services; • the contract has commercial substance; and • collection of substantially all of the consideration we are entitled to under the contract is probable. We identify performance obligations in our contracts with customers, which may include software licenses and/or related maintenance and services. We determine the transaction price based on the amount of consideration we expect to receive in exchange for transferring the promised goods or services to the customer. We allocate the transaction price in the contract to each distinct performance obligation in an amount that depicts the relative amount of consideration we expect to receive in exchange for satisfying each performance obligation. Revenue is recognized when performance obligations are satisfied. Our contract payment terms are typically net 30 days . We assess collectability based on a number of factors including collection history and creditworthiness of the customer, and we may mitigate exposures to credit risk by requiring payments in advance. If we determine that collectability related to a contract is not probable, we may not record revenue until collectability becomes probable at a later date. Our revenues are recorded based on the transaction price excluding amounts collected on behalf of third parties. For example, indirect taxes which we collect and remit to governmental authorities are excluded from our revenues. Nature of Products and Services Our on-premises software licenses are sold through both perpetual and term-based license agreements. These licensing arrangements provide customers with the same product functionality and differ mainly in the duration over which the customer benefits from the software. We deliver our software licenses electronically. Electronic delivery occurs when we provide the customer with access to the software and license key via a secure portal. Revenue from on-premises software licenses is generally recognized upfront at the point in time when the software is made available to the customer. Our contracts with customers for on-premises software licenses include maintenance services and may also include training and/or professional services. Maintenance services agreements consist of fees for providing software updates on an if and when available basis and for providing technical support for software products for a specified term. We believe that our software updates and technical support each have the same pattern of transfer to the customer and are substantially the same. Therefore, we consider these updates and technical support to be a single distinct performance obligation. Revenues allocated to maintenance services are recognized ratably as the maintenance services are provided. Revenues related to training services are billed on a fixed fee basis and are recognized as the services are delivered. Payments received in advance of services performed are deferred and recognized when the related services are performed. Revenues related to professional services are billed on a time and materials basis and are recognized as the services are performed. We also provide cloud-based subscriptions, which allow customers to access our software during a contractual period without taking possession of the software. We recognize revenue related to these cloud-based subscriptions ratably over the life of the subscription agreement beginning when the customer first has access to the software. Revenues from our cloud-based subscriptions are included in license revenues. Judgments and Estimates Our contracts with customers often include promises to transfer multiple products and services. Determining whether products and services are considered distinct performance obligations that should be accounted for separately from one another sometimes requires judgment. Judgment is also required to determine standalone selling prices (“SSP”s) for each distinct performance obligation. We typically have more than one SSP for each of our products and services based on customer stratification, which is based on the size of the customer, their geographic region and market segment. For perpetual software licenses, we estimate SSPs by considering our pricing objectives and discounting practices. For our cloud-based subscriptions and for maintenance services, training and professional services, SSPs are generally observable using standalone sales and/or renewals. Our on-premises term-based software licenses generally do not have directly observable inputs for determining SSP. Therefore, we determine SSP using other observable inputs including customer-buying patterns, renewal rates and cumulative spend comparisons. We evaluate contracts with customers that include options to purchase additional goods or services to determine whether the options give rise to a separate performance obligation that is material. If we determine the options give rise to a separate performance obligation that is material, the revenue allocated to such options is not recognized until the option is exercised or the option expires. Assets Recognized from the Costs to Obtain a Contract with a Customer We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We have determined that certain costs related to our sales incentive programs meet the requirements to be capitalized and deferred. Assets recorded are included in prepaid expenses and other current assets and other long-term assets. We amortize these deferred costs proportionate with related revenues over the benefit period, currently estimated to be four years. We consider the benefit period to exceed the initial contract term for certain costs because of anticipated renewals and because our sales commission rates for renewal contracts are not commensurate with sales commissions for initial contracts. Prior to our adoption of the new revenue recognition standard, we recognized sales commissions expense as incurred. Contract Assets Contract assets represent the portion of the transaction price from a contract with a customer where control has transferred, but for which we currently do not have the contractual right to invoice. These assets, included within prepaid expenses and other current assets, are also subject to impairment risk. We reduce our gross contract asset balance for any impairments identified based on our consideration of a combination of factors including past collection experience, credit quality of the customer, age of other receivables balances due from the customer and current economic conditions. Revenue Recognition - ASC 605 Our revenue recognition accounting policy for ASC 605 is shown below. We applied the revenue recognition accounting policy for ASC 605 to our disclosures in Note 8, which include amounts presented for 2018. We generate revenues primarily in the form of software license fees and related maintenance and services fees. Software license fees include fees from the sales of perpetual, term and subscription licenses. Maintenance and services fees primarily consist of fees for maintenance services (including support and unspecified upgrades and enhancements when and if they are available), training and professional services that are not essential to the functionality of the software. We recognize revenues when all of the following conditions are met: • there is persuasive evidence of an arrangement; • the software or services have been delivered to the customer; • the amount of fees to be paid by the customer is fixed or determinable; and • the collection of the related fees is probable. We use click-through license agreements, signed agreements and purchase orders as evidence of an arrangement. We deliver all of our software electronically. Electronic delivery occurs when we provide the customer with access to the software and license key via a secure portal. We assess whether the fee is fixed or determinable at the outset of the arrangement. Our typical terms of payment are due 30 days from delivery. We assess collectability based on a number of factors such as collection history and creditworthiness of the customer. If we determine that collectability is not probable, revenue is deferred until collectability becomes probable, generally upon receipt of cash. Substantially all of our software licenses are sold in multiple-element arrangements that include maintenance services and may include professional services and training. Vendor specific objective evidence ("VSOE") of the fair value for software licenses is not available as our software licenses are never sold without maintenance; however, VSOE generally exists for all undelivered elements and any services that are not essential to the functionality of the delivered software. Therefore, we account for delivered software licenses under the residual method. Maintenance agreements consist of fees for providing software updates on a when and if available basis and technical support for software products ("post-contract support" or "PCS") for an initial term, generally one year. We have established VSOE of the fair value for maintenance on perpetual licenses based on stated substantive renewal rates or the price when sold on a standalone basis. Stated renewal rates are considered to be substantive if they are at least 15% of the actual price charged for the software license. VSOE of the fair value for standalone maintenance contracts is considered to have been established when a substantial majority of individual sales transactions within the previous 12 months falls within a reasonably narrow range, which we have defined to be plus or minus 15% of the median sales price of actual standalone sales transactions. License arrangements may include professional services and training. In determining whether professional services and training revenues should be accounted for separately from license revenues, we evaluate: • whether such services are considered essential to the functionality of the software using factors such as the nature of the software products; • whether they are ready for use by the customer upon receipt; • the nature of the services, which typically do not involve significant customization to or development of the underlying software code; • the availability of services from other vendors; • whether the timing of payments for license revenues coincides with performance of services; and • whether milestones or acceptance criteria exist that affect the realizability of the software license fee. To date, professional services have not been considered essential to the functionality of the software. The VSOE of the fair value of our professional services and training is based on the price for these same services when they are sold separately. Revenues related to professional services are billed on a time and materials basis and are recognized as the services are performed. Revenues related to training services are billed on a fixed fee basis and are recognized as the services are delivered. Payments received in advance of services performed are deferred and recognized when the related services are performed. When software is licensed for a specified term or on a subscription basis, fees for maintenance and support are generally bundled with the license fee over the entire term of the contract. In these cases, we do not have VSOE of the fair value for maintenance and support. Revenues related to term and subscription license fees are recognized ratably over the contract term beginning on the date the customer has access to the software license key and continuing through the end of the contract term. We do not offer refunds and therefore have not recorded any sales return allowance for any of the periods presented. Upon a periodic review of outstanding accounts receivable, amounts that are deemed to be uncollectable are written off against the allowance for doubtful accounts. We account for taxes collected from customers and remitted to governmental authorities on a net basis and exclude them from revenues.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments purchased with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents are recorded at fair value. We maintain cash and cash equivalent balances which exceed the insured limits by the Federal Deposit Insurance Corporation.
Investments	Investments We classify our investment securities as available-for-sale. Our investment securities are stated at fair value and reported in short-term investments and long-term investments. Investments in securities with maturities of less than one year, or where management's intent is to use the investments to fund current operations, are classified as short-term investments. Investments with maturities greater than one year are classified as long-term investments. Unrealized gains and losses on available-for-sale securities are excluded from net income and reported, net of tax, in other comprehensive income (loss). Realized gains and losses and declines in the value of securities judged to be other-than-temporary are determined based on the specific identification method and are included in other income, net. In order to determine whether a decline in value is other-than-temporary, we evaluate, among other factors, our intent and ability to recover the amortized cost basis of the security. Interest on securities classified as available-for-sale is included in other income, net.
Accounts Receivable, Net	Accounts Receivable, Net Accounts receivable consist of amounts billed and currently due from customers. Our accounts receivable are subject to collection risk. Our gross accounts receivable is reduced for this risk by a provision for doubtful accounts. This provision is for estimated losses resulting from the inability of our customers to make required payments. It is an estimate and is regularly evaluated for adequacy by taking into consideration a combination of factors. We look at factors such as past collection experience, credit quality of the customer, age of the receivable balance and current economic conditions. These factors are reviewed to determine whether a provision for doubtful accounts should be recorded to reduce the receivable balance to the amount believed to be collectible.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives range from approximately one to twelve years. Leasehold improvements are depreciated over the shorter of the estimated useful life or the remaining lease term. When assets are retired or disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gains or losses are included in results of operations. Maintenance and repairs that do not improve or extend the lives of the respective assets are charged to expense in the period incurred.
Business Combinations	Business Combinations As of the date of an acquisition, we recognize the identifiable assets acquired and liabilities assumed at fair value. Intangible assets acquired are measured at their acquisition date fair value using valuation techniques that are subject to judgment. Any excess of the consideration over the fair value of identifiable net assets is recorded as goodwill. Amounts that are not part of the consideration transferred are recognized separately from a business combination and are expensed as incurred.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Intangible assets with a finite life are typically amortized over their useful lives which range from three to five years. Goodwill is tested for impairment on an annual basis in the third quarter and more frequently if circumstances indicate that the carrying value may not be recoverable. As part of our goodwill impairment test, we first perform a qualitative assessment to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying amount. For purposes of this assessment, we consider the enterprise to be the reporting unit. If we determine it is more likely than not that the fair value of our reporting unit is less than its carrying amount, we will perform a quantitative assessment to determine whether the fair value of our reporting unit is less than its carrying amount. We have not had any impairments of the goodwill balance.
Leases	Leases Leases are categorized at their inception as either operating or capital leases. Within some lease agreements, rent holidays and other incentives are included. Rent expense is recognized using the straight-line method over the term of the agreement, which generally begins once control of the space is obtained. Any cash incentives received are treated as a reduction of expense over the term of the agreement.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Property and equipment, intangible assets with a finite life and other long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Recoverability of an asset to be held and used is tested by comparing the carrying amount of the asset to the estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. No impairment of long-lived assets occurred in the periods presented.
Software Development Costs	Software Development Costs Software development costs associated with the development of new products, enhancements of existing products and quality assurance activities consist of employee, consulting and other external personnel costs. The costs incurred internally from the research and development ("R&D") of computer software products are charged to expense until technological feasibility has been established for the product. Once technological feasibility is established, all software costs are capitalized until the product is available for release to customers. Judgment is required in determining when technological feasibility of a product is established. To date, we have determined that technological feasibility of software products is reached shortly before the products are released. Costs incurred after establishment of technological feasibility have not been material, and therefore, we have expensed all R&D costs as they were incurred. R&D expenses primarily consist of personnel-related costs attributable to our R&D personnel and allocated overhead, which includes facilities-related costs. We capitalize certain costs relating to software developed or modified solely to meet our internal requirements and for which there are no substantive plans to market the software. To date, we have not capitalized any such costs as these costs have not been material.
Intangible Asset Costs	Intangible Asset Costs Costs related to filing and pursuing patent and trademark applications are expensed as incurred, as recoverability of such expenditures is uncertain. These intangible asset-related legal costs are generally reported as a component of general and administrative expenses.
Advertising Expenses	Advertising Expenses We expense all advertising costs as incurred and classify such costs as sales and marketing expenses. Advertising expenses for the years ended December 31, 2018 , 2017 and 2016 were $36.5 million , $28.2 million and $21.7 million , respectively.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method in accordance with authoritative guidance for income taxes. Deferred income tax assets are recognized for deductible temporary differences, net operating loss carryforwards, and tax credit carryforwards if it is more likely than not that the tax benefits will be realized. We consider future taxable income, historical operating results and ongoing prudent and feasible tax planning strategies in assessing the need for a valuation allowance. A valuation allowance is recorded to reduce our deferred income tax assets to the net amount that we believe is more likely than not to be realized. In the event we determine that we are able to realize our deferred income tax assets in excess of our net recorded amount, we would reduce the valuation allowance associated with the deferred income tax assets in the period the determination is made, which may result in a tax benefit in the statement of operations. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Our assumptions, judgments and estimates relative to the value of net deferred income taxes take into account predictions of the amount and category of future taxable income, such as income from operations or capital gains income. Actual operating results and the underlying amount and category of income in future years could render our current assumptions, judgments and estimates of recoverable net deferred income taxes inaccurate. Any of the assumptions, judgments and estimates mentioned above could cause our actual income tax obligations to differ from our estimates, thus materially impacting our financial position and results of operations.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents, investments, accounts receivable and contract assets. Our investment portfolio consists of investment-grade securities diversified among security types, industries and issuers. Our cash and cash equivalents and investments are held and managed by recognized financial institutions that follow our investment policy. Our policy limits the amount of credit exposure to any one security issue or issuer. We extend credit to customers based upon an evaluation of the customer's financial condition. As of December 31, 2018 and 2017 , no individual customer accounted for 10% or more of total accounts receivable. As of December 31, 2018 , no individual customer accounted for 10% or more of total contract assets. For the years ended December 31, 2018 , 2017 and 2016 , no individual customer represented 10% or more of our total revenues.
Fair Value Measurements	Fair Value Measurements We categorize assets and liabilities recorded at fair value on our consolidated balance sheets based upon the level of judgment associated with inputs used to measure their fair value. The levels of the fair value hierarchy are as follows: • Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. • Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3—Inputs are unobservable inputs based on our own assumptions and valuation techniques used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. We establish fair value of our assets and liabilities using the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date and using a fair value hierarchy based on the inputs used to measure fair value. The carrying amounts reported in the consolidated financial statements approximate the fair value for accounts receivable, accounts payable, and accrued and other current liabilities, due to their short-term nature. We value our cash equivalents and investments using quoted prices for identical instruments in active markets when available. If we are unable to obtain quoted prices for identical instruments in active markets, we value our cash equivalents and investments using quoted market prices for comparable instruments. To date, all of our cash equivalents and investments have been valued using one of these two methodologies.
Stock-Based Compensation	Stock-Based Compensation We record compensation expense for stock-based transactions including employee and non-employee stock option and restricted stock unit ("RSU") awards granted under our 2004 Equity Incentive Plan (the "2004 Plan") and our 2013 Equity Incentive Plan, as amended, (the "2013 Plan" and together with the 2004 Plan, the "Plans"). We also record compensation expense related to employee contributions made under our 2013 Employee Stock Purchase Plan ("2013 ESPP"). These contributions are used to purchase shares of our Class A common stock at a discount. Stock-based compensation expense is measured and recognized in the financial statements based on fair value. The fair value of each RSU award is determined based on the closing price of our Class A common stock as reported on the New York Stock Exchange on the date of grant. The fair value of each stock option award is determined at the date of grant by applying the Black-Scholes option pricing model. We also use the Black-Scholes option pricing model to determine the fair value of each common share issued under the 2013 ESPP. The fair value for 2013 ESPP grants is determined on the first day of each offering period. The Black-Scholes option pricing model utilizes the value of our underlying common stock at the measurement date, the expected or contractual term of the option or offering period, the expected volatility of our common stock, risk-free interest rates and expected dividend yield of our common stock. Prior to our initial public offering ("IPO") in May 2013, the fair value of our common stock was determined by our board of directors. After the completion of our IPO, our common stock has been valued by reference to the closing price of our Class A common stock as reported on the New York Stock Exchange. We recognize stock-based compensation expense using the straight-line method over the requisite service period. We account for forfeitures as they occur. For awards subject to technology milestones, we recognize compensation cost over the requisite service period if it is probable that the technology milestone will be met. If our assessment of the probability of the technology milestone being met changes, we recognize the impact of the change in estimate in the period of the change. Excess tax benefits and deficiencies resulting from the settlement of stock awards are recorded to income tax expense (benefit).
New Accounting Pronouncements	Recently Adopted Accounting Pronouncements We adopted the new revenue recognition accounting standard, codified as ASC 606, effective January 1, 2018. The new revenue recognition standard changed the way we recognize revenue, including the identification of contractual performance obligations and the allocation of transaction price, to depict the transfer of promised goods or services to customers at the amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. We adopted the new revenue recognition standard on a modified retrospective basis and applied the new revenue recognition standard only to contracts that were not completed contracts prior to January 1, 2018. Upon adoption, we recorded an adjustment of $146.8 million to our accumulated deficit. The adjustment was offset by a $105.9 million reduction to deferred revenue, which was primarily related to on-premises term licenses, and the addition of a $40.9 million contract asset. The new revenue recognition standard materially impacts the timing of revenue recognition related to our on-premises term license agreements. Prior to our adoption of the new revenue recognition standard, we historically recognized revenue related to on-premises term license agreements ratably over the term of the licensing agreement. These revenues were then included in license revenues. Under the new revenue recognition standard, revenue allocable to the license portion of the arrangement is recognized in license revenues upon delivery of the license. Revenues allocated to maintenance services continue to be recognized ratably and are included in maintenance and services revenues. Under the new revenue recognition standard, we allocate total transaction price to performance obligations based on estimated standalone selling prices, which impacts the timing of revenue recognition depending on when each performance obligation is recognized. These impacts to the timing of revenue recognition also affect our deferred revenue balances. The new revenue recognition standard requires the capitalization of certain incremental costs of obtaining a contract, which impacts the periods in which we record our sales commissions expense. Prior to our adoption of the new revenue recognition standard, we recognized sales commissions expense as incurred. Under the new revenue recognition standard, we are required to recognize these expenses over the period of benefit associated with these costs. This results in a deferral of sales commissions expense each period and subsequent amortization of those costs over the estimated benefit period. Upon adoption of the new revenue recognition standard, we reduced our accumulated deficit by $25.5 million and recognized an offsetting asset for deferred sales commissions related to contracts that were not completed contracts prior to January 1, 2018. For further discussion regarding the impacts of adopting the new revenue recognition standard, see Note 8. In October 2016, the FASB issued Accounting Standards Update ("ASU") 2016-16 related to the accounting for income tax effects on intra-entity transfers of assets other than inventory. The new guidance requires reporting entities to recognize tax expense from the sale of assets when the transfer occurs, even though the pre-tax effects of the transaction are eliminated in consolidation. We adopted the new standard in the first quarter of 2018 on a modified retrospective basis. The adoption resulted in the recognition of a U.S. deferred tax asset, which was fully offset by a corresponding increase to the valuation allowance on our U.S. federal and state deferred income tax assets, and therefore did not have a material impact on our consolidated financial statements. Recent Accounting Pronouncements Not yet Adopted In February 2016, the FASB issued ASU 2016-02, a new lease accounting standard codified as ASC 842. ASC 842 will require lessees to recognize right-of-use assets and lease liabilities on the balance sheet for leases with terms longer than 12 months. The new standard also will require additional disclosure of qualitative and quantitative information about the amounts recorded in the financial statements related to lease agreements. We will adopt the new lease accounting standard on January 1, 2019, using the modified retrospective transition method and recording a cumulative-effect balance sheet adjustment. In adopting ASC 842, we will utilize certain practical expedients available under the standard. These practical expedients include waiving reassessment of conclusions reached under the previous lease standard as to whether contracts contain leases, how to classify leases identified and how to account for initial direct costs incurred. We will also utilize the practical expedient to use hindsight as of the date of adoption to determine the terms of our leases and to evaluate our right-of-use assets for impairment. We plan to utilize certain policy elections available under ASC 842, including waiving the recognition of right-of-use assets and lease liabilities for leases with initial terms of 12 months or less, and combining lease and non-lease components when accounting for leases of real estate assets. Based on the size of our future operating lease commitments as of December 31, 2018 (discussed in Note 11), the adoption of the new lease accounting standard will have a material impact on our balance sheet on the date of adoption. In June 2016, the FASB issued ASU 2016-13, related to credit losses. The new guidance replaces the existing incurred loss impairment model with an expected credit loss model and requires a financial asset measured at amortized cost to be presented at the net amount expected to be collected. ASU 2016-13 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. We are currently evaluating the impact that this standard will have on our consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Activity Related to Provision for Doubtful Accounts	Activity related to our provision for doubtful accounts was as follows: Year Ended December 31, 2018 2017 2016 (in thousands) Balance at the beginning of the year $ 1,003 $ 1,065 $ 888 Bad debt expense 1,168 650 750 Accounts written off (563 ) (712 ) (573 ) Balance at the end of the year $ 1,608 $ 1,003 $ 1,065

Balance Sheet Detail (Tables)

Balance Sheet Detail (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Property and Equipment, Net	Property and equipment, net consisted of the following: Useful Life December 31, (in months) 2018 2017 (in thousands) Computer equipment and software 36 $ 93,671 $ 98,737 Furniture and fixtures 36 26,914 25,232 Leasehold improvements 12-150 86,082 85,482 Construction in progress 10,693 313 217,360 209,764 Less: Accumulated depreciation (122,823 ) (103,011 ) $ 94,537 $ 106,753
Accrued Compensation and Employee Related Benefits	Accrued compensation and employee-related benefits consisted of the following: December 31, 2018 2017 (in thousands) Accrued commissions $ 33,820 $ 31,333 Accrued bonuses 34,767 25,435 Accrued vacation 17,375 14,512 Other 19,193 25,110 Total $ 105,155 $ 96,390

Short-Term and Long-Term Inve_2

Short-Term and Long-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment	The following tables present our short-term and long-term investments in available-for-sale securities based on remaining contractual years to maturity: December 31, 2018 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) Short-term investments Commercial paper $ 7,949 $ — $ — $ 7,949 U.S. treasury securities 206,486 24 (457 ) 206,053 U.S. agency securities 18,576 — (61 ) 18,515 Corporate bonds 137,119 — (281 ) 136,838 Total short-term investments 370,130 24 (799 ) 369,355 Long-term investments U.S. treasury securities 13,352 5 (50 ) 13,307 Corporate bonds 13,025 2 (56 ) 12,971 Total long-term investments 26,377 7 (106 ) 26,278 Total short-term and long-term investments $ 396,507 $ 31 $ (905 ) $ 395,633 December 31, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) Short-term investments Commercial paper $ 9,970 $ — $ — $ 9,970 U.S. treasury securities 160,206 — (121 ) 160,085 U.S. agency securities 9,917 — (24 ) 9,893 Corporate bonds 46,901 3 (65 ) 46,839 Total short-term investments 226,994 3 (210 ) 226,787 Long-term investments U.S. treasury securities 79,371 — (202 ) 79,169 U.S. agency securities 18,570 — (102 ) 18,468 Corporate bonds 50,880 — (153 ) 50,727 Total long-term investments 148,821 — (457 ) 148,364 Total short-term and long-term investments $ 375,815 $ 3 $ (667 ) $ 375,151
Schedule of Unrealized Loss on Investments	The following table presents the fair values and the gross unrealized losses related to our investments in available-for-sale securities that were in an unrealized loss position as of December 31, 2018 , summarized by the length of time that the investments have been in a continuous unrealized loss position: December 31, 2018 Less Than 12 Months 12 Months or Greater Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (in thousands) Short-term investments U.S. treasury securities $ 89,320 $ (143 ) $ 79,472 $ (314 ) $ 168,792 $ (457 ) U.S. agency securities — — 18,515 (61 ) 18,515 (61 ) Corporate bonds 91,455 (131 ) 45,383 (150 ) 136,838 (281 ) Total short-term investments 180,775 (274 ) 143,370 (525 ) 324,145 (799 ) Long-term investments U.S. treasury securities 9,855 (50 ) — — 9,855 (50 ) Corporate bonds 11,389 (56 ) — — 11,389 (56 ) Total long-term investments 21,244 (106 ) — — 21,244 (106 ) Total short-term and long-term investments $ 202,019 $ (380 ) $ 143,370 $ (525 ) $ 345,389 $ (905 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets	The following tables present the fair value of our financial assets using the fair value hierarchy: December 31, 2018 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents Money market funds $ 610,732 $ — $ — $ 610,732 Corporate bonds — 3,009 — 3,009 Short-term investments Commercial paper — 7,949 — 7,949 U.S. treasury securities — 206,053 — 206,053 U.S. agency securities — 18,515 — 18,515 Corporate bonds — 136,838 — 136,838 Long-term investments U.S. treasury securities — 13,307 — 13,307 Corporate bonds — 12,971 — 12,971 Total $ 610,732 $ 398,642 $ — $ 1,009,374 December 31, 2017 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents Money market funds $ 582,835 $ — $ — $ 582,835 Commercial paper — 8,984 — 8,984 Short-term investments Commercial paper — 9,970 — 9,970 U.S. treasury securities — 160,085 — 160,085 U.S. agency securities — 9,893 — 9,893 Corporate bonds — 46,839 — 46,839 Long-term investments U.S. treasury securities — 79,169 — 79,169 U.S. agency securities — 18,468 — 18,468 Corporate bonds — 50,727 50,727 Total $ 582,835 $ 384,135 $ — $ 966,970

Business Combinations Business

Business Combinations Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Purchase Price Allocation	The following table summarizes the purchase price allocation based on the estimated fair value of the net assets acquired: June 7, 2018 (in thousands) Cash $ 53 Technology asset 3,500 Goodwill 7,447 Net assets acquired $ 11,000	The following table summarizes the purchase price allocation based on the estimated fair value of the net assets acquired: August 1, 2017 (in thousands) Cash $ 161 Technology asset 5,000 Goodwill 19,552 Other liabilities, net (586 ) Net assets acquired $ 24,127

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Consolidated Balance Sheets - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated balance sheet: December 31, 2018 December 31, 2017 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) (in thousands) Assets Current assets Cash and cash equivalents $ 653,022 $ — $ 653,022 $ 627,878 Short-term investments 369,355 — 369,355 226,787 Accounts receivable, net 236,063 — 236,063 203,366 Prepaid expenses and other current assets 155,012 (121,418 ) 33,594 30,514 Income taxes receivable 2,268 97 2,365 673 Total current assets 1,415,720 (121,321 ) 1,294,399 1,089,218 Long-term investments 26,278 — 26,278 148,364 Property and equipment, net 94,537 — 94,537 106,753 Goodwill 42,530 — 42,530 35,083 Deferred income taxes 4,733 3,170 7,903 5,287 Other long-term assets 50,927 (34,871 ) 16,056 14,090 Total assets $ 1,634,725 $ (153,022 ) $ 1,481,703 $ 1,398,795 Liabilities and stockholders' equity Current liabilities Accounts payable $ 6,652 $ — $ 6,652 $ 4,448 Accrued compensation and employee-related benefits 105,155 — 105,155 96,390 Other accrued liabilities 55,896 — 55,896 37,722 Income taxes payable 2,982 (46 ) 2,936 4,743 Deferred revenue 377,892 199,210 577,102 419,426 Total current liabilities 548,577 199,164 747,741 562,729 Deferred revenue 16,306 12,232 28,538 28,058 Other long-term liabilities 56,257 (1,718 ) 54,539 54,385 Total liabilities 621,140 209,678 830,818 645,172 Stockholders' equity Common stock 8 — 8 8 Additional paid-in capital 1,340,628 — 1,340,628 1,168,563 Accumulated other comprehensive loss (11,458 ) 1,902 (9,556 ) (11,991 ) Accumulated deficit (315,593 ) (364,602 ) (680,195 ) (402,957 ) Total stockholders' equity 1,013,585 (362,700 ) 650,885 753,623 Total liabilities and stockholders' equity $ 1,634,725 $ (153,022 ) $ 1,481,703 $ 1,398,795 Consolidated Statements of Operations - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of operations: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Revenues License $ 555,581 $ (57,531 ) $ 498,050 $ 429,204 $ 481,659 Maintenance and services 599,771 (114,872 ) 484,899 447,855 345,284 Total revenues 1,155,352 (172,403 ) 982,949 877,059 826,943 Cost of revenues License 21,407 (484 ) 20,923 13,534 7,003 Maintenance and services 121,217 514 121,731 100,025 92,087 Total cost of revenues 142,624 30 142,654 113,559 99,090 Gross profit 1,012,728 (172,433 ) 840,295 763,500 727,853 Operating expenses Sales and marketing 593,786 26,768 620,554 517,446 476,506 Research and development 382,886 — 382,886 334,148 302,759 General and administrative 125,805 (119 ) 125,686 102,871 88,149 Total operating expenses 1,102,477 26,649 1,129,126 954,465 867,414 Operating loss (89,749 ) (199,082 ) (288,831 ) (190,965 ) (139,561 ) Other income, net 17,872 (46 ) 17,826 12,266 2,134 Loss before income tax expense (71,877 ) (199,128 ) (271,005 ) (178,699 ) (137,427 ) Income tax expense 5,165 1,068 6,233 6,861 7,022 Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Consolidated Statements of Comprehensive Loss - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of comprehensive loss: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Other comprehensive income (loss), net of tax: Foreign currency translation (937 ) 3,585 2,648 (12,920 ) 950 Net unrealized loss on available-for-sale securities (213 ) — (213 ) (664 ) — Comprehensive loss $ (78,192 ) $ (196,611 ) $ (274,803 ) $ (199,144 ) $ (143,499 ) Consolidated Statements of Cash Flows - Reconciliation of the Impacts from the Adoption of the New Revenue Recognition Standard The following schedule summarizes the impacts from the adoption of the new revenue recognition standard on our consolidated statement of cash flows: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Operating activities Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Adjustments to reconcile net loss to net cash provided by operating activities Depreciation and amortization expense 35,787 — 35,787 44,746 43,006 Amortization (accretion) on investments, net (424 ) — (424 ) 359 — Stock-based compensation expense 238,731 — 238,731 210,283 185,712 Deferred income taxes (2,180 ) 942 (1,238 ) (2,988 ) 1,219 Changes in operating assets and liabilities Accounts receivable, net (36,519 ) — (36,519 ) 12,493 (78,197 ) Prepaid expenses and other assets (95,347 ) 91,351 (3,996 ) 8,054 (18,987 ) Income taxes receivable (1,675 ) (99 ) (1,774 ) (515 ) (56 ) Deferred revenue 56,555 108,141 164,696 123,938 116,860 Accounts payable and accrued liabilities 38,396 — 38,396 13,529 71,157 Income taxes payable (1,586 ) (49 ) (1,635 ) 2,528 997 Net cash provided by operating activities 154,696 90 154,786 226,867 177,262 Investing activities Purchases of property and equipment (20,446 ) — (20,446 ) (61,823 ) (60,732 ) Business combinations, net of cash acquired (10,947 ) — (10,947 ) (23,966 ) (16,399 ) Purchases of investments (285,277 ) — (285,277 ) (421,719 ) — Maturities of investments 262,835 — 262,835 30,630 — Sales of investments 2,171 — 2,171 14,916 — Net cash used in investing activities (51,664 ) — (51,664 ) (461,962 ) (77,131 ) Financing activities Proceeds from issuance of common stock 44,710 — 44,710 38,856 34,356 Repurchases of common stock (120,024 ) — (120,024 ) (79,991 ) (20,009 ) Net cash provided by (used in) financing activities (75,314 ) — (75,314 ) (41,135 ) 14,347 Effect of exchange rate changes on cash and cash equivalents (2,574 ) (90 ) (2,664 ) (4,609 ) (1,661 ) Net increase (decrease) in cash and cash equivalents 25,144 — 25,144 (280,839 ) 112,817 Cash and cash equivalents Beginning of year 627,878 — 627,878 908,717 795,900 End of year $ 653,022 $ — $ 653,022 $ 627,878 $ 908,717
Contract with Customer, Asset and Liability	The following table presents the activity impacting our contract assets during the year ended December 31, 2018 : Contract Assets (in thousands) Balance at December 31, 2017 $ — Adoption of ASC 606 40,854 Contract assets transferred to receivables (37,698 ) Additions to contract assets 102,437 Balance at December 31, 2018 $ 105,593 Contract assets are included in prepaid expenses and other current assets. There were no material impairments of contract assets during the year ended December 31, 2018 . The following table presents the activity impacting our deferred revenue balances during the year ended December 31, 2018 : Deferred Revenue (in thousands) Balance at December 31, 2017 $ 447,484 Adoption of ASC 606 (105,933 ) Deferred revenue recognized (314,765 ) Additional amounts deferred 367,412 Balance at December 31, 2018 $ 394,198 Assets Recognized from the Costs to Obtain our Contracts with Customers We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We amortize these deferred costs proportionate with related revenues over the benefit period, currently estimated to be four years. The following table presents the activity impacting our deferred contract costs during the year ended December 31, 2018 : Deferred Contract Costs (in thousands) Balance at December 31, 2017 $ — Adoption of ASC 606 25,489 Additional contract costs deferred 37,528 Amortization of deferred contract costs (11,616 ) Balance at December 31, 2018 $ 51,401

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Option Activity	A summary of the option activity during the year ended December 31, 2018 follows: Options Outstanding Shares Weighted Average Exercise Price per Share Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Balances at December 31, 2017 3,017,113 $ 10.13 Options exercised (1,097,730 ) 9.60 Balances at December 31, 2018 1,919,383 $ 10.44 3.12 $ 210,283 Vested and expected to vest at December 31, 2018 1,919,383 $ 10.44 3.12 $ 210,283 Exercisable at December 31, 2018 1,886,570 $ 9.67 3.04 $ 208,146
Summary of RSU Activity	A summary of the RSU activity, including RSU awards subject to technology milestones, during the year ended December 31, 2018 follows: Number of Shares Underlying Outstanding RSUs Weighted-Average Grant-Date Fair Value per RSU Non-Vested outstanding at December 31, 2017 7,178,015 $ 62.79 RSUs granted 4,374,326 92.25 RSUs vested (3,526,004 ) 67.74 RSUs forfeited (831,883 ) 68.16 Non-Vested outstanding at December 31, 2018 7,194,454 $ 77.66
Schedule Of Equity Based Awards Available	The summary of shares available for issuance of equity-based awards (including stock options, RSUs and shares issuable under our 2013 ESPP) during the year ended December 31, 2018 follows: Shares Available for Grant 2013 Plan 2013 ESPP Balances at December 31, 2017 7,207,291 3,666,392 Authorized 4,023,117 804,623 Granted (4,374,326 ) (491,471 ) Forfeited 831,883 — Balances at December 31, 2018 7,687,965 3,979,544
Fair Value Assumptions - Options	For the year ended December 31, 2016, the fair value of options was estimated using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2016 Risk-free interest rates 1.2% Expected term 5.2 years Expected dividends None Expected volatility 48.0%
Fair Value Assumptions - ESPP	For the years ended December 31, 2018 , 2017 and 2016 , the fair value of common share purchase rights under the 2013 ESPP was estimated using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2018 2017 2016 Risk-free interest rates 2.1% - 2.5% 1.1% - 1.5% 0.5% - 0.6% Expected term 0.5 years 0.5 years 0.5 years Expected dividends None None None Expected volatility 28.7% - 44.5% 28.6% - 30.5% 42.0% - 50.1%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	The components of our loss before income tax expense consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States $ (44,488 ) $ (134,723 ) $ (100,725 ) International (27,389 ) (43,976 ) (36,702 ) Total $ (71,877 ) $ (178,699 ) $ (137,427 )
Schedule Of Income Tax Expense Benefit By Geographic Area Table	Income tax expense (benefit) consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States $ (108 ) $ (592 ) $ 2,147 International 5,273 7,453 4,875 Total $ 5,165 $ 6,861 $ 7,022
Schedule of Components of Income Tax Expense	The provision for income taxes consisted of the following: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Current: Federal $ — $ — $ 1,447 State 197 233 402 Foreign 9,425 10,704 5,230 Total current income tax expense 9,622 10,937 7,079 Deferred: Federal (241 ) (892 ) 258 State (64 ) 67 40 Foreign (4,152 ) (3,251 ) (355 ) Total deferred income tax benefit (4,457 ) (4,076 ) (57 ) Total income tax expense $ 5,165 $ 6,861 $ 7,022
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the U.S. federal statutory income tax provision (benefit) (computed by multiplying the U.S. federal statutory rate of 21% in 2018 and 35% in both 2017 and 2016 by loss before income tax expense) to the effective income tax expense for each year follows: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Income tax benefit at statutory rate $ (15,094 ) $ (62,545 ) $ (48,098 ) State taxes, net of federal tax benefit (1,835 ) (4,714 ) (3,466 ) Impact of foreign income taxes 12,239 23,232 14,566 Impact of Tax Cuts and Jobs Act of 2017 3,367 87,584 — Research and development and other tax credits (17,933 ) (12,563 ) (8,462 ) Stock-based compensation (35,858 ) (13,466 ) 5,098 Non-deductible meals and entertainment expenses 2,313 1,182 1,212 Impact of valuation allowance 57,284 (13,598 ) 46,174 Other, net 682 1,749 (2 ) Total income tax expense $ 5,165 $ 6,861 $ 7,022
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences and carryforwards that gave rise to deferred income tax assets and liabilities consisted of the following: December 31, 2018 2017 As Reported (ASC 606) As Reported (ASC 605) (in thousands) Deferred income tax assets: Net operating loss carryforwards $ 154,409 $ 133,187 Tax credit carryforwards 73,020 59,343 Stock-based compensation 12,612 15,512 Accrued compensation 13,803 11,487 Deferred revenue 4,120 5,334 Deferred rent 12,065 12,483 Depreciation and amortization 34,350 966 Other 1,766 1,149 Total deferred income tax assets 306,145 239,461 Deferred income tax liabilities: Prepaid assets 3,011 4,177 Deferred commissions 12,676 — Total deferred income tax liabilities 15,687 4,177 Net deferred income tax assets before valuation allowance 290,458 235,284 Less: valuation allowance (287,935 ) (230,545 ) Net deferred income tax assets $ 2,523 $ 4,739 Reported as: Deferred income taxes 4,733 5,287 Other long-term liabilities (2,210 ) (548 ) Net deferred income tax assets $ 2,523 $ 4,739
Schedule of Unrecognized Tax Benefits Roll Forward	The following table shows the gross changes in our unrecognized tax position. Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) As Reported (ASC 605) As Reported (ASC 605) (in thousands) Balance, beginning of year $ 19,881 $ 12,909 $ 10,781 Gross increases to tax positions related to prior periods 1,174 1,289 28 Gross decreases to tax positions related to prior periods (291 ) — — Gross increases related to current tax positions 7,377 5,683 2,100 Balance, end of year $ 28,141 $ 19,881 $ 12,909

Commitments and Contigencies (T

Commitments and Contigencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments	The following table presents our non-lease contractual commitments as of December 31, 2018 : Payments Due by Year Total 2019 2020 2021 2022 2023 Thereafter (in thousands) Contractual commitments $ 42,631 $ 24,295 $ 10,947 $ 7,193 $ 168 $ 28 $ —
Future Minimum Lease Payments	The following table presents our non-cancellable future minimum lease payments, net of future sublease receipts expected to be received under non-cancellable subleases, as of December 31, 2018 : Year Ending December 31, Operating Lease Commitments Expected Sublease Receipts Net (in thousands) 2019 $ 44,569 $ (9,912 ) $ 34,657 2020 45,835 (8,125 ) 37,710 2021 46,562 (1,208 ) 45,354 2022 45,858 (625 ) 45,233 2023 46,789 (128 ) 46,661 Thereafter 136,829 — 136,829 Total $ 366,442 $ (19,998 ) $ 346,444

Segments and Information abou_2

Segments and Information about Revenues by Geographic Region (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	The following table presents our revenues by geographic region of end users who purchased products or services for the periods presented below: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands) United States and Canada $ 797,874 $ 683,073 $ 605,773 $ 586,494 International 357,478 299,876 271,286 240,449 Total revenues $ 1,155,352 $ 982,949 $ 877,059 $ 826,943

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Earnings Per Share, Basic and Diluted	The following table presents the computation of basic and diluted net loss per share and includes additional information regarding the impacts from the adoption of the new revenue recognition standard for the year ended December 31, 2018: Year Ended December 31, 2018 2017 2016 As Reported (ASC 606) Impacts from Adoption Without Adoption (ASC 605) As Reported (ASC 605) As Reported (ASC 605) (in thousands, except per share data) Net loss per share - basic and diluted Net loss $ (77,042 ) $ (200,196 ) $ (277,238 ) $ (185,560 ) $ (144,449 ) Weighted average shares outstanding used to compute basic and diluted net loss per share 82,632 82,632 78,869 75,162 Net loss per share - basic and diluted $ (0.93 ) $ (3.36 ) $ (2.35 ) $ (1.92 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following shares were excluded from the computation of diluted net loss per share for the periods presented as their effect would have been antidilutive: Year Ended December 31, 2018 2017 2016 (in thousands) Shares subject to outstanding common stock awards 9,237 10,488 12,017

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	The following table contains selected unaudited financial data for each quarter of 2018 and 2017 . The unaudited information should be read in conjunction with our financial statements and these notes to the consolidated financial statements. We believe that the following unaudited information reflects all normal recurring adjustments necessary for a fair presentation of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. Three Months Ended Dec 31, 2018 Sept 30, 2018 June 30, 2018 March 31, 2018 Dec 31, 2018 Sept 30, 2018 June 30, 2018 March 31, 2018 As Reported (ASC 606) Without Adoption (ASC 605) (in thousands, except per share amounts) Total revenues $ 336,276 $ 290,580 $ 282,289 $ 246,207 $ 275,748 $ 239,591 $ 243,566 $ 224,044 Gross profit 296,081 255,801 247,064 213,782 235,574 204,785 208,326 191,610 Net income (loss) 2,833 (21,337 ) (12,066 ) (46,472 ) (67,348 ) (71,297 ) (59,567 ) (79,026 ) Net income (loss) per share: Basic $ 0.03 $ (0.26 ) $ (0.15 ) $ (0.57 ) $ (0.80 ) $ (0.86 ) $ (0.72 ) $ (0.98 ) Diluted $ 0.03 $ (0.26 ) $ (0.15 ) $ (0.57 ) $ (0.80 ) $ (0.86 ) $ (0.72 ) $ (0.98 ) Three Months Ended Dec 31, 2017 Sept 30, 2017 June 30, 2017 March 31, 2017 As Reported (ASC 605) (in thousands, except per share amounts) Total revenues $ 249,356 $ 214,917 $ 212,880 $ 199,906 Gross profit 219,046 184,988 186,215 173,251 Net loss (41,838 ) (46,553 ) (42,522 ) (54,647 ) Net loss per share: Basic and diluted $ (0.52 ) $ (0.59 ) $ (0.54 ) $ (0.71 )

Description of Business Narrati

Description of Business Narrative (Details)	Dec. 31, 2018product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products	5

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle
Amortization period, deferred commissions	4 years
Threshold for Asset Recognition From Costs of Obtaining a Contract	1 year
Class of Stock
Impairment of Long-Lived Assets Held-for-use	$ 0	$ 0	$ 0
Cumulative translation losses	(10,600,000)	(11,300,000)
Foreign currency transaction gain (loss)	$ (500,000)	4,100,000	(600,000)
Number of operating segments | segment	1
Terms of payment due	30 days
Advertising expenses	$ 36,500,000	$ 28,200,000	$ 21,700,000
VSOE sales % variance compared to median sales price of standalone transactions	15.00%
VSOE sales period of evaluation	12 months
Accumulated Deficit | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				$ 146,800,000
Contract Asset
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				40,854,000
Contract Asset | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				40,900,000
Minimum
Class of Stock
Useful life of property and equipment (in years)	1 year
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum
Class of Stock
Useful life of property and equipment (in years)	12 years
Finite-Lived Intangible Asset, Useful Life	5 years
Deferred Revenue
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				(105,933,000)
Deferred Revenue | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				105,900,000
Deferred contract costs
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				25,489,000
Deferred contract costs | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Adoption of ASC 606				$ 25,500,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Activity Related to Allowance for Doubtful Accounts (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
Balance at the beginning of the year	$ 1,003	$ 1,065	$ 888
Bad debt expense	1,168	650	750
Accounts written off	(563)	(712)	(573)
Balance at the end of the year	$ 1,608	$ 1,003	$ 1,065

Balance Sheet Detail - Property

Balance Sheet Detail - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment
Depreciation	$ 34,000	$ 43,900	$ 42,700
Property and equipment, Gross	217,360	209,764
Less: Accumulated depreciation	(122,823)	(103,011)
Property and equipment, net	$ 94,537	106,753
Minimum
Property, Plant and Equipment
Useful life (in months)	1 year
Maximum
Property, Plant and Equipment
Useful life (in months)	12 years
Computer equipment and software
Property, Plant and Equipment
Useful life (in months)	36 months
Property and equipment, Gross	$ 93,671	98,737
Furniture and fixtures
Property, Plant and Equipment
Useful life (in months)	36 months
Property and equipment, Gross	$ 26,914	25,232
Leasehold improvements
Property, Plant and Equipment
Property and equipment, Gross	$ 86,082	85,482
Leasehold improvements | Minimum
Property, Plant and Equipment
Useful life (in months)	12 months
Leasehold improvements | Maximum
Property, Plant and Equipment
Useful life (in months)	150 months
Construction in progress
Property, Plant and Equipment
Property and equipment, Gross	$ 10,693	$ 313

Balance Sheet Detail - Addition

Balance Sheet Detail - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and amortization expense on property and equipment and lease assets	$ 34	$ 43.9	$ 42.7
Intangible Assets, Period Increase (Decrease)	3.5
Amortization of Intangible Assets	1.8	$ 0.8	$ 0.3
Goodwill, Period Increase (Decrease)	$ 7.4

Balance Sheet Detail - Accrued

Balance Sheet Detail - Accrued Compensation and Other Employee Related Benefits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued commissions	$ 33,820	$ 31,333
Accrued bonuses	34,767	25,435
Accrued vacation	17,375	14,512
Other	19,193	25,110
Total	$ 105,155	$ 96,390

Short-Term and Long-Term Inve_3

Short-Term and Long-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities
Amortized Cost	$ 396,507	$ 375,815
Unrealized Gains	31	3
Unrealized Losses	(905)	(667)
Fair Value	395,633	375,151
Short-term Investments
Schedule of Available-for-sale Securities
Amortized Cost	370,130	226,994
Unrealized Gains	24	3
Unrealized Losses	(799)	(210)
Fair Value, current	369,355	226,787
Short-term Investments | Commercial Paper, Not Included with Cash and Cash Equivalents
Schedule of Available-for-sale Securities
Amortized Cost	7,949	9,970
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value, current	7,949	9,970
Short-term Investments | U.S. Treasury Securities
Schedule of Available-for-sale Securities
Amortized Cost	206,486	160,206
Unrealized Gains	24	0
Unrealized Losses	(457)	(121)
Fair Value, current	206,053	160,085
Short-term Investments | U.S. Agency Securities
Schedule of Available-for-sale Securities
Amortized Cost	18,576	9,917
Unrealized Gains	0	0
Unrealized Losses	(61)	(24)
Fair Value, current	18,515	9,893
Short-term Investments | Corporate bonds
Schedule of Available-for-sale Securities
Amortized Cost	137,119	46,901
Unrealized Gains	0	3
Unrealized Losses	(281)	(65)
Fair Value, current	136,838	46,839
Long-term Investments
Schedule of Available-for-sale Securities
Amortized Cost	26,377	148,821
Unrealized Gains	7	0
Unrealized Losses	(106)	(457)
Fair Value, noncurrent	26,278	148,364
Long-term Investments | U.S. Treasury Securities
Schedule of Available-for-sale Securities
Amortized Cost	13,352	79,371
Unrealized Gains	5	0
Unrealized Losses	(50)	(202)
Fair Value, noncurrent	13,307	79,169
Long-term Investments | U.S. Agency Securities
Schedule of Available-for-sale Securities
Amortized Cost		18,570
Unrealized Gains		0
Unrealized Losses		(102)
Fair Value, noncurrent		18,468
Long-term Investments | Corporate bonds
Schedule of Available-for-sale Securities
Amortized Cost	13,025	50,880
Unrealized Gains	2	0
Unrealized Losses	(56)	(153)
Fair Value, noncurrent	$ 12,971	$ 50,727

Short-Term and Long-Term Inve_4

Short-Term and Long-Term Investments Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Income and Expenses [Abstract]
Interest Income	$ 17	$ 8.5	$ 2.7

Short-Term and Long-Term Inve_5

Short-Term and Long-Term Investments Schedule of Investments in an Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2018USD ($)
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 202,019
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(380)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	143,370
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(525)
Debt Securities, Available-for-sale, Unrealized Loss Position	345,389
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(905)
Short-term Investments
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	180,775
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(274)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	143,370
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(525)
Debt Securities, Available-for-sale, Unrealized Loss Position	324,145
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(799)
Short-term Investments | U.S. Treasury Securities
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	89,320
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(143)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	79,472
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(314)
Debt Securities, Available-for-sale, Unrealized Loss Position	168,792
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(457)
Short-term Investments | U.S. Agency Securities
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,515
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(61)
Debt Securities, Available-for-sale, Unrealized Loss Position	18,515
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(61)
Short-term Investments | Corporate bonds
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	91,455
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(131)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	45,383
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(150)
Debt Securities, Available-for-sale, Unrealized Loss Position	136,838
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(281)
Long-term Investments
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	21,244
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(106)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position	21,244
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(106)
Long-term Investments | U.S. Treasury Securities
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	9,855
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(50)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position	9,855
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(50)
Long-term Investments | Corporate bonds
Schedule of Available-for-sale Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	11,389
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Less, Accumulated Loss	(56)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position	11,389
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (56)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	$ 1,009,374	$ 966,970
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	610,732	582,835
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	398,642	384,135
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	0	0
Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	610,732	582,835
Cash equivalents | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	610,732	582,835
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value		8,984
Commercial Paper | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value		8,984
Commercial Paper, Not Included with Cash and Cash Equivalents | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	7,949	9,970
Commercial Paper, Not Included with Cash and Cash Equivalents | Short-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	7,949	9,970
U.S. Treasury Securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	206,053	160,085
U.S. Treasury Securities | Short-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	206,053	160,085
U.S. Treasury Securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	13,307	79,169
U.S. Treasury Securities | Long-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	13,307	79,169
U.S. Agency Securities | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	18,515	9,893
U.S. Agency Securities | Short-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	18,515	9,893
U.S. Agency Securities | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value		18,468
U.S. Agency Securities | Long-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value		18,468
Corporate bonds | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	3,009
Corporate bonds | Cash Equivalents | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	3,009
Corporate bonds | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	136,838	46,839
Corporate bonds | Short-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	136,838	46,839
Corporate bonds | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	12,971	50,727
Corporate bonds | Long-term Investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments fair value	$ 12,971	$ 50,727

Stockholders' Equity (Details)

Stockholders' Equity (Details)	12 Months Ended
	Dec. 31, 2018USD ($)votes$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Apr. 26, 2018USD ($)	Nov. 01, 2016USD ($)
Class of Stock
Approved repurchase amount | $					$ 200,000,000
Stock Repurchase Program, Increase to Authorized Amount | $				$ 300,000,000
Repurchase of common stock (in shares)	1,220,596	1,264,428	446,517
Average price (in USD per share) | $ / shares	$ 98.33	$ 63.26
Repurchase of common stock | $	$ 120,024,000	$ 79,991,000	$ 20,009,000
Remaining authorized repurchase amount | $	$ 280,000,000
Common Class B
Class of Stock
Shares authorized for issuance	75,000,000	75,000,000
Common stock par value (in USD per share) | $ / shares	$ 0.0001	$ 0.0001
Votes per share entitled to share holder | votes	10
Common Class A
Class of Stock
Shares authorized for issuance	750,000,000	750,000,000
Common stock par value (in USD per share) | $ / shares	$ 0.0001	$ 0.0001
Votes per share entitled to share holder | votes	1
Preferred Stock
Class of Stock
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock par value (in USD per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock outstanding (in shares)	0	0

Business Combinations (Details)

Business Combinations (Details) - USD ($) $ in Thousands	Jun. 07, 2018	Aug. 01, 2017	Mar. 01, 2016	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition
Technology asset amortization period	5 years	5 years
Goodwill				$ 42,530	$ 35,083
Empirical Systems
Business Acquisition
Cash	$ 53
Technology asset	3,500
Goodwill	7,447
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	11,000
Payments to Acquire Businesses, Gross	$ 11,000
ClearGraph
Business Acquisition
Cash		$ 161
Technology asset		5,000
Goodwill		19,552
Other Liabilities, net		(586)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		24,127
Payments to Acquire Businesses, Gross		$ 24,100
Hyper
Business Acquisition
Technology asset			$ 1,800
Payments to Acquire Businesses, Gross			$ 16,400

Revenue (Details)

Revenue (Details)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Threshold for Asset Recognition From Costs of Obtaining a Contract	1 year
Amortization period, deferred commissions	4 years

Revenue Balance Sheet (Details)

Revenue Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Initial Application Period Cumulative Effect Transition
Cash and cash equivalents	$ 653,022	$ 627,878	$ 908,717	$ 795,900
Short-term investments	369,355	226,787
Accounts receivable, net	236,063	203,366
Prepaid expenses and other current assets	155,012	30,514
Income taxes receivable	2,268	673
Total current assets	1,415,720	1,089,218
Long-term investments	26,278	148,364
Property and equipment, net	94,537	106,753
Goodwill	42,530	35,083
Deferred income taxes	4,733	5,287
Other long-term assets	50,927	14,090
Total assets	1,634,725	1,398,795
Accounts payable	6,652	4,448
Accrued compensation and employee-related benefits	105,155	96,390
Other accrued liabilities	55,896	37,722
Income taxes payable	2,982	4,743
Deferred revenue	377,892	419,426
Total current liabilities	548,577	562,729
Deferred revenue	16,306	28,058
Other long-term liabilities	56,257	54,385
Total liabilities	621,140	645,172
Common stock	8	8
Additional paid-in capital	1,340,628	1,168,563
Accumulated other comprehensive loss	(11,458)	(11,991)
Accumulated deficit	(315,593)	(402,957)
Total stockholders' equity	1,013,585	753,623	$ 791,848	$ 733,945
Total liabilities and stockholders' equity	1,634,725	1,398,795
Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Cash and cash equivalents	0	0
Short-term investments	0
Accounts receivable, net	0
Prepaid expenses and other current assets	(121,418)
Income taxes receivable	97
Total current assets	(121,321)
Long-term investments	0
Property and equipment, net	0
Goodwill	0
Deferred income taxes	3,170
Other long-term assets	(34,871)
Total assets	(153,022)
Accounts payable	0
Accrued compensation and employee-related benefits	0
Other accrued liabilities	0
Income taxes payable	(46)
Deferred revenue	199,210
Total current liabilities	199,164
Deferred revenue	12,232
Other long-term liabilities	(1,718)
Total liabilities	209,678
Common stock	0
Additional paid-in capital	0
Accumulated other comprehensive loss	1,902
Accumulated deficit	(364,602)
Total stockholders' equity	(362,700)
Total liabilities and stockholders' equity	(153,022)
Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Cash and cash equivalents	653,022	$ 627,878
Short-term investments	369,355
Accounts receivable, net	236,063
Prepaid expenses and other current assets	33,594
Income taxes receivable	2,365
Total current assets	1,294,399
Long-term investments	26,278
Property and equipment, net	94,537
Goodwill	42,530
Deferred income taxes	7,903
Other long-term assets	16,056
Total assets	1,481,703
Accounts payable	6,652
Accrued compensation and employee-related benefits	105,155
Other accrued liabilities	55,896
Income taxes payable	2,936
Deferred revenue	577,102
Total current liabilities	747,741
Deferred revenue	28,538
Other long-term liabilities	54,539
Total liabilities	830,818
Common stock	8
Additional paid-in capital	1,340,628
Accumulated other comprehensive loss	(9,556)
Accumulated deficit	(680,195)
Total stockholders' equity	650,885
Total liabilities and stockholders' equity	$ 1,481,703

Revenue Income Statement (Detai

Revenue Income Statement (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues		$ 336,276	$ 290,580	$ 282,289	$ 246,207	$ 249,356	$ 214,917	$ 212,880	$ 199,906	$ 1,155,352	$ 877,059	$ 826,943
Total cost of revenues	[1]									142,624	113,559	99,090
Gross profit		296,081	255,801	247,064	213,782	219,046	184,988	186,215	173,251	1,012,728	763,500	727,853
Sales and marketing	[1]									593,786	517,446	476,506
Research and development	[1]									382,886	334,148	302,759
General and administrative	[1]									125,805	102,871	88,149
Total operating expenses										1,102,477	954,465	867,414
Operating loss										(89,749)	(190,965)	(139,561)
Other income, net										17,872	12,266	2,134
Loss before income tax expense										(71,877)	(178,699)	(137,427)
Income tax expense										5,165	6,861	7,022
Net loss		2,833	(21,337)	(12,066)	(46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	(77,042)	(185,560)	(144,449)
Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										(172,403)
Total cost of revenues										30
Gross profit										(172,433)
Sales and marketing										26,768
Research and development										0
General and administrative										(119)
Total operating expenses										26,649
Operating loss										(199,082)
Other income, net										(46)
Loss before income tax expense										(199,128)
Income tax expense										1,068
Net loss										(200,196)
Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues		275,748	239,591	243,566	224,044					982,949
Total cost of revenues										142,654
Gross profit		235,574	204,785	208,326	191,610					840,295
Sales and marketing										620,554
Research and development										382,886
General and administrative										125,686
Total operating expenses										1,129,126
Operating loss										(288,831)
Other income, net										17,826
Loss before income tax expense										(271,005)
Income tax expense										6,233
Net loss		$ (67,348)	$ (71,297)	$ (59,567)	$ (79,026)					(277,238)
License
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										555,581	429,204	481,659
Total cost of revenues										21,407	13,534	7,003
License | Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										(57,531)
Total cost of revenues										(484)
License | Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										498,050
Total cost of revenues										20,923
Maintenance and services
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										599,771	447,855	345,284
Total cost of revenues										121,217	$ 100,025	$ 92,087
Maintenance and services | Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										(114,872)
Total cost of revenues										514
Maintenance and services | Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Total revenues										484,899
Total cost of revenues										$ 121,731
[1]	Includes stock-based compensation expense as follows: Year Ended December 31, 2018 2017 2016 (in thousands)Cost of revenues$13,392 $11,029 $10,595Sales and marketing87,105 74,065 68,411Research and development111,965 104,280 91,044General and administrative26,269 20,909 15,662

Revenue Comprehensive Income (D

Revenue Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition
Net loss	$ 2,833	$ (21,337)	$ (12,066)	$ (46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	$ (77,042)	$ (185,560)	$ (144,449)
Foreign currency translation									(937)	(12,920)	950
Net unrealized loss on available-for-sale securities									(213)	(664)	0
Comprehensive loss									(78,192)	$ (199,144)	$ (143,499)
Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Net loss									(200,196)
Foreign currency translation									3,585
Net unrealized loss on available-for-sale securities									0
Comprehensive loss									(196,611)
Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Net loss	$ (67,348)	$ (71,297)	$ (59,567)	$ (79,026)					(277,238)
Foreign currency translation									2,648
Net unrealized loss on available-for-sale securities									(213)
Comprehensive loss									$ (274,803)

Revenue Cash Flow (Details)

Revenue Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition
Net loss	$ 2,833	$ (21,337)	$ (12,066)	$ (46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	$ (77,042)	$ (185,560)	$ (144,449)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization expense									35,787	44,746	43,006
Amortization (accretion) on investments, net									(424)	359	0
Stock-based compensation expense									238,731	210,283	185,712
Deferred income taxes									(2,180)	(2,988)	1,219
Changes in operating assets and liabilities
Accounts receivable, net									(36,519)	12,493	(78,197)
Prepaid expenses and other assets									(95,347)	8,054	(18,987)
Income taxes receivable									(1,675)	(515)	(56)
Deferred revenue									56,555	123,938	116,860
Accounts payable and accrued liabilities									38,396	13,529	71,157
Income taxes payable									(1,586)	2,528	997
Net cash provided by operating activities									154,696	226,867	177,262
Investing activities
Purchases of property and equipment									(20,446)	(61,823)	(60,732)
Business combinations, net of cash acquired									(10,947)	(23,966)	(16,399)
Purchases of investments									(285,277)	(421,719)	0
Maturities of investments									262,835	30,630	0
Sales of investments									2,171	14,916	0
Net cash used in investing activities									(51,664)	(461,962)	(77,131)
Financing activities
Proceeds from issuance of common stock									44,710	38,856	34,356
Repurchases of common stock									(120,024)	(79,991)	(20,009)
Net cash provided by (used in) financing activities									(75,314)	(41,135)	14,347
Effect of exchange rate changes on cash and cash equivalents									(2,574)	(4,609)	(1,661)
Net increase (decrease) in cash and cash equivalents									25,144	(280,839)
Cash and Cash Equivalents, Period Increase (Decrease)									25,144	(280,839)	112,817
Cash and cash equivalents
Beginning of year				627,878				$ 908,717	627,878	908,717	795,900
End of year	653,022				627,878				653,022	627,878	$ 908,717
Impacts from Adoption | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition
Net loss									(200,196)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization expense									0
Amortization (accretion) on investments, net									0
Stock-based compensation expense									0
Deferred income taxes									942
Changes in operating assets and liabilities
Accounts receivable, net									0
Prepaid expenses and other assets									91,351
Income taxes receivable									(99)
Deferred revenue									108,141
Accounts payable and accrued liabilities									0
Income taxes payable									(49)
Net cash provided by operating activities									90
Investing activities
Purchases of property and equipment									0
Business combinations, net of cash acquired									0
Purchases of investments									0
Maturities of investments									0
Sales of investments									0
Net cash used in investing activities									0
Financing activities
Proceeds from issuance of common stock									0
Repurchases of common stock									0
Net cash provided by (used in) financing activities									0
Effect of exchange rate changes on cash and cash equivalents									(90)
Net increase (decrease) in cash and cash equivalents									0
Cash and cash equivalents
Beginning of year				0					0
End of year	0				0				0	0
Without Adoption (ASC 605)
Revenue, Initial Application Period Cumulative Effect Transition
Net loss	(67,348)	$ (71,297)	$ (59,567)	(79,026)					(277,238)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization expense									35,787
Amortization (accretion) on investments, net									(424)
Stock-based compensation expense									238,731
Deferred income taxes									(1,238)
Changes in operating assets and liabilities
Accounts receivable, net									(36,519)
Prepaid expenses and other assets									(3,996)
Income taxes receivable									(1,774)
Deferred revenue									164,696
Accounts payable and accrued liabilities									38,396
Income taxes payable									(1,635)
Net cash provided by operating activities									154,786
Investing activities
Purchases of property and equipment									(20,446)
Business combinations, net of cash acquired									(10,947)
Purchases of investments									(285,277)
Maturities of investments									262,835
Sales of investments									2,171
Net cash used in investing activities									(51,664)
Financing activities
Proceeds from issuance of common stock									44,710
Repurchases of common stock									(120,024)
Net cash provided by (used in) financing activities									(75,314)
Effect of exchange rate changes on cash and cash equivalents									(2,664)
Net increase (decrease) in cash and cash equivalents									25,144
Cash and cash equivalents
Beginning of year				$ 627,878					627,878
End of year	$ 653,022				$ 627,878				$ 653,022	$ 627,878

Revenue Contract Assets (Detail

Revenue Contract Assets (Details) - Contract Asset - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018
Contract Asset Rollforward
Balance at December 31, 2017	$ 0
Adoption of ASC 606		$ 40,854
Contract assets transferred to receivables	(37,698)
Additions to contract assets	102,437
Balance at December 31, 2018	$ 105,593

Revenue Deferred Revenue (Detai

Revenue Deferred Revenue (Details) - Deferred Revenue - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018
Deferred Revenue Rollforward
Balance at December 31, 2017	$ 447,484
Adoption of ASC 606		$ (105,933)
Deferred revenue recognized	(314,765)
Additional amounts deferred	367,412
Balance at December 31, 2018	$ 394,198

Revenue Deferred Contract Costs

Revenue Deferred Contract Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Deferred contract costs, expected to be amortized within the next 12 months	$ 16,500
Deferred contract costs
Capitalized Contract Cost
Balance at December 31, 2017	0
Adoption of ASC 606		$ 25,489
Additional contract costs deferred	37,528
Amortization of deferred contract costs	(11,616)
Balance at December 31, 2018	$ 51,401

Revenue Performance Obligations

Revenue Performance Obligations (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, Remaining Performance Obligation, Amount	$ 240.1
Recognized Over Next 24 Months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, Remaining Performance Obligation, Amount	$ 191.7

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award
Unrecognized compensation cost	$ 502.4
Weighted-average remaining vesting period (in years)	2 years 9 months 18 days
Weighted-average fair value options granted (in USD per share)	$ 23.73
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Award expiration period (in years)	10 years
Vesting period (in years)	4 years
Total intrinsic value of options exercised	$ 92.4	$ 74.5	$ 63.3
Fair value of options vested	$ 0.4	$ 1.2	$ 7.8
2004 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for grant (in shares)	0
ESPP
Share-based Compensation Arrangement by Share-based Payment Award
Annual increase in shares authorized for grant (percent)	1.00%
Annual increase in shares authorized for grant (in shares)	4,000,000
ESPP | Common Class A
Share-based Compensation Arrangement by Share-based Payment Award
ESPP maximum deduction (percent)	15.00%
ESPP purchase period (in months)	6 months
ESPP purchase price, percent of fair market value (percent)	85.00%
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Annual increase in shares authorized for grant (percent)	5.00%
Shares available for grant (in shares)	7,687,965	7,207,291
Shares issued (in shares)	4,374,326
2013 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Options granted (in shares)	0	0
2013 Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Weighted-average grant date fair value of RSUs granted (in USD per share)	$ 92.25	$ 60.62	$ 44.61
Fair value of RSUs vested in period	$ 342.3	$ 185.7	$ 92.5

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Option Activity Under Stock option Plan (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Options Outstanding
Beginning of balance (in shares)	3,017,113
Options exercised (in shares)	(1,097,730)
Ending of balance (in shares)	1,919,383	3,017,113
Vested and expected to vest (in shares)	1,919,383
Exercisable (in shares)	1,886,570
Weighted Average Exercise Price per Share
Beginning balance (in USD per share)	$ 10.13
Options exercised (in USD per share)	9.60
Ending balance (in USD per share)	10.44	$ 10.13
Vested and expected to vest (in USD per share)	10.44
Exercisable (in USD per share)	$ 9.67
Weighted-Average Remaining Contractual Term
Ending balance (term)	3 years 1 month 13 days
Vested and expected to vest (term)	3 years 1 month 13 days
Exercisable (term)	3 years 14 days
Aggregate Intrinsic Value
Ending balance	$ 210,283
Vested and expected to vest	210,283
Exercisable	$ 208,146
2013 Plan
Options Outstanding
Options granted (in shares)	0	0

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - 2013 Plan - Restricted Stock Units (RSUs) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares Underlying Outstanding RSUs
Beginning of period (in shares)	7,178,015
RSUs granted (in shares)	4,374,326
RSUs vested (in shares)	(3,526,004)
RSUs forfeited (in shares)	(831,883)
End of period (in shares)	7,194,454	7,178,015
Weighted-Average Grant-Date Fair Value per RSU
Beginning of period (in USD per share)	$ 62.79
RSUs granted (in USD per share)	92.25	$ 60.62	$ 44.61
RSUs vested (in USD per share)	67.74
RSUs forfeited (in USD per share)	68.16
End of period(in USD per share)	$ 77.66	$ 62.79

Stock-Based Compensation - Equi

Stock-Based Compensation - Equity Based Awards (including Stock Options and RSUs (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
2013 Plan
Shares Available for Grant
Beginning of period (in shares)	7,207,291
Authorized (in shares)	4,023,117
Shares granted (in shares)	(4,374,326)
Shares forfeited (in shares)	831,883
End of period (in shares)	7,687,965	7,207,291
2013 ESPP | Common Class A
Shares Available for Grant
Beginning of period (in shares)	3,666,392
Authorized (in shares)	804,623
Shares granted (in shares)	(491,471)	(604,177)	(549,327)
Options forfeited (in shares)	0
End of period (in shares)	3,979,544	3,666,392

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value of Options Estimated Using Black-Scholes Option Pricing Model (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ESPP
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rates, minimum (percent)	2.10%	1.10%	0.50%
Risk-free interest rates, maximum (percent)	2.50%	1.50%	0.60%
Expected term (in years)	6 months	6 months	6 months
Expected dividends	$ 0	$ 0	$ 0
Expected volatility, minimum (percent)	28.70%	28.60%	42.00%
Expected volatility, minimum (percent)	44.50%	30.50%	50.10%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rates (percent)	1.20%
Expected term (in years)	5 years 1 month 25 days
Expected dividends	$ 0
Expected volatility (percent)	48.00%

Income Taxes - Income Before Pr

Income Taxes - Income Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ (44,488)	$ (134,723)	$ (100,725)
International	(27,389)	(43,976)	(36,702)
Loss before income tax expense	$ (71,877)	$ (178,699)	$ (137,427)

Income Taxes - Income Taxes Exp

Income Taxes - Income Taxes Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense Benefit
Total income tax expense (benefit)	$ 5,165	$ 6,861	$ 7,022
United States
Income Tax Expense Benefit
Total income tax expense (benefit)	(108)	(592)	2,147
International
Income Tax Expense Benefit
Total income tax expense (benefit)	$ 5,273	$ 7,453	$ 4,875

Income Taxes - Provision for Cu

Income Taxes - Provision for Current and Deferred Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 0	$ 0	$ 1,447
State	197	233	402
Foreign	9,425	10,704	5,230
Total current income tax expense	9,622	10,937	7,079
Deferred:
Federal	(241)	(892)	258
State	(64)	67	40
Foreign	(4,152)	(3,251)	(355)
Total deferred income tax benefit	(4,457)	(4,076)	(57)
Total income tax expense	$ 5,165	$ 6,861	$ 7,022

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes Differs from U.S. Federal Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax benefit at statutory rate	$ (15,094)	$ (62,545)	$ (48,098)
State taxes, net of federal tax benefit	(1,835)	(4,714)	(3,466)
Impact of foreign income taxes	12,239	23,232	14,566
Impact of Tax Cuts and Jobs Act of 2017	3,367	87,584	0
Research and development and other tax credits	(17,933)	(12,563)	(8,462)
Stock-based compensation	(35,858)	(13,466)	5,098
Non-deductible meals and entertainment expenses	2,313	1,182	1,212
Impact of valuation allowance	57,284	(13,598)	46,174
Other, net	682	1,749	(2)
Total income tax expense	$ 5,165	$ 6,861	$ 7,022

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Deferred income tax assets:
Net operating loss carryforwards	$ 154,409	$ 133,187
Tax credit carryforwards	73,020	59,343
Stock-based compensation	12,612	15,512
Accrued compensation	13,803	11,487
Deferred revenue	4,120	5,334
Deferred rent	12,065	12,483
Depreciation and amortization	34,350	966
Other	1,766	1,149
Total deferred income tax assets	306,145	239,461
Deferred income tax liabilities:
Prepaid assets	3,011	4,177
Deferred commissions	12,676
Total deferred income tax liabilities	15,687	4,177
Net deferred income tax assets before valuation allowance	290,458	235,284
Less: valuation allowance	(287,935)	(230,545)	$ (46,700)
Net deferred income tax assets	2,523	4,739
Components of Deferred Tax Assets Reported As
Deferred income taxes	4,733	5,287
Other long-term liabilities	(2,210)	(548)
Net deferred income tax assets	$ 2,523	$ 4,739

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 999,700,000
R&D tax credit carryforwards	93,300,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	4,600,000
Cash held by foreign subsidiaries	35,900,000
Unrecognized tax benefits	28,141,000	$ 19,881,000	$ 12,909,000	$ 10,781,000
Unrecognized tax benefits, liability	3,100,000	1,400,000	700,000
Income tax penalties and interest expense	0	0	$ 0
Valuation Allowance	$ 287,935,000	$ 230,545,000		$ 46,700,000

Income Taxes - Changes in Unrec

Income Taxes - Changes in Unrecognized Tax Position (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance, beginning of year	$ 19,881	$ 12,909	$ 10,781
Gross increases to tax positions related to prior periods	1,174	1,289	28
Gross decreases to tax positions related to prior periods	(291)	0	0
Gross increases related to current tax positions	7,377	5,683	2,100
Balance, end of year	$ 28,141	$ 19,881	$ 12,909

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense, Net	$ 34,700	$ 41,100	$ 44,100
Operating Lease Commitments
Operating Leases, 2019	44,569
Operating Leases, 2020	45,835
Operating Leases, 2021	46,562
Operating Leases, 2022	45,858
Operating Leases, 2023	46,789
Operating Leases, Thereafter	136,829
Operating Leases, Total	366,442
Expected Sublease Receipts
Expected Sublease Receipts, 2019	(9,912)
Expected Sublease Receipts, 2020	(8,125)
Expected Sublease Receipts, 2021	(1,208)
Expected Sublease Receipts, 2022	(625)
Expected Sublease Receipts, 2023	(128)
Expected Sublease Receipts, Thereafter	0
Expected Sublease Receipts, Total	(19,998)
Net
Net, 2019	34,657
Net, 2020	37,710
Net, 2021	45,354
Net, 2022	45,233
Net, 2023	46,661
Net, Thereafter	136,829
Net, Total	346,444
Contractual Commitments
Total	42,631
2,019	24,295
2,020	10,947
2,021	7,193
2,022	168
2,023	28
Thereafter	$ 0

Retirement Plan Additional Info

Retirement Plan Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employer matching contributions	$ 7.5	$ 3.7	$ 3.6

Segments and Information abou_3

Segments and Information about Revenues by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information
Total revenues	$ 336,276	$ 290,580	$ 282,289	$ 246,207	$ 249,356	$ 214,917	$ 212,880	$ 199,906	$ 1,155,352	$ 877,059	$ 826,943
United States and Canada
Segment Reporting Information
Total revenues									797,874	605,773	586,494
International
Segment Reporting Information
Total revenues									357,478	$ 271,286	$ 240,449
Without Adoption (ASC 605)
Segment Reporting Information
Total revenues	$ 275,748	$ 239,591	$ 243,566	$ 224,044					982,949
Without Adoption (ASC 605) | United States and Canada
Segment Reporting Information
Total revenues									683,073
Without Adoption (ASC 605) | International
Segment Reporting Information
Total revenues									$ 299,876

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic [Abstract]
Net loss	$ 2,833	$ (21,337)	$ (12,066)	$ (46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	$ (77,042)	$ (185,560)	$ (144,449)
Weighted average shares outstanding used to compute basic and diluted net loss per share									82,632	78,869	75,162
Net loss per share - basic and diluted					$ (0.52)	$ (0.59)	$ (0.54)	$ (0.71)	$ (0.93)	$ (2.35)	$ (1.92)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									9,237	10,488	12,017
Without Adoption (ASC 605)
Earnings Per Share, Basic [Abstract]
Net loss	$ (67,348)	$ (71,297)	$ (59,567)	$ (79,026)					$ (277,238)
Weighted average shares outstanding used to compute basic and diluted net loss per share									82,632
Net loss per share - basic and diluted									$ (3.36)
Accounting Standards Update 2014-09 | Impacts from Adoption
Earnings Per Share, Basic [Abstract]
Net loss									$ (200,196)

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 336,276	$ 290,580	$ 282,289	$ 246,207	$ 249,356	$ 214,917	$ 212,880	$ 199,906	$ 1,155,352	$ 877,059	$ 826,943
Gross profit	296,081	255,801	247,064	213,782	219,046	184,988	186,215	173,251	1,012,728	763,500	727,853
Net income (loss)	$ 2,833	$ (21,337)	$ (12,066)	$ (46,472)	$ (41,838)	$ (46,553)	$ (42,522)	$ (54,647)	$ (77,042)	$ (185,560)	$ (144,449)
Earnings Per Share, Basic and Diluted [Abstract]
Net loss per share - basic and diluted					$ (0.52)	$ (0.59)	$ (0.54)	$ (0.71)	$ (0.93)	$ (2.35)	$ (1.92)
Revenue, Initial Application Period Cumulative Effect Transition
Basic	$ 0.03	$ (0.26)	$ (0.15)	$ (0.57)					(0.93)	(2.35)	(1.92)
Diluted	$ 0.03	$ (0.26)	$ (0.15)	$ (0.57)					$ (0.93)	$ (2.35)	$ (1.92)
Without Adoption (ASC 605)
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 275,748	$ 239,591	$ 243,566	$ 224,044					$ 982,949
Gross profit	235,574	204,785	208,326	191,610					840,295
Net income (loss)	$ (67,348)	$ (71,297)	$ (59,567)	$ (79,026)					$ (277,238)
Earnings Per Share, Basic and Diluted [Abstract]
Net loss per share - basic and diluted									$ (3.36)
Revenue, Initial Application Period Cumulative Effect Transition
Basic	$ (0.80)	$ (0.86)	$ (0.72)	$ (0.98)
Diluted	$ (0.80)	$ (0.86)	$ (0.72)	$ (0.98)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	Feb. 22, 2019	Jan. 03, 2019	Dec. 31, 2018
Subsequent Event
Operating Leases, Future Minimum Payments Due			$ 366,442
Subsequent Event
Subsequent Event
Stock Donated to Charity		209,384
Donated stock-based expense		$ 24,200
Office Building | Subsequent Event
Subsequent Event
Operating Leases, Future Minimum Payments Due	$ 21,700

Uncategorized Items - data-2018

Label	Element	Value
Accounting Standards Update 2016-09 [Member] | Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 439,000
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(439,000)
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	166,089,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	164,406,000
Accounting Standards Update 2014-09 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,683,000