Zendesk (ZEN) 10-Q 8 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Trading Symbol	ZEN
Entity Registrant Name	Zendesk, Inc.
Entity Central Index Key	1,463,172
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		98,961,539

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 109,258	$ 93,677
Marketable securities	138,440	131,190
Accounts receivable, net of allowance for doubtful accounts of $2,264 and $1,269 as of March 31, 2017 and December 31, 2016, respectively	39,105	37,343
Prepaid expenses and other current assets	17,982	17,608
Total current assets	304,785	279,818
Marketable securities, noncurrent	68,320	75,168
Property and equipment, net	60,842	62,731
Goodwill and intangible assets, net	52,699	53,296
Other assets	4,382	4,272
Total assets	491,028	475,285
Current liabilities:
Accounts payable	5,890	4,555
Accrued liabilities	18,448	19,106
Accrued compensation and related benefits	21,664	20,281
Deferred revenue	130,129	123,276
Total current liabilities	176,131	167,218
Deferred revenue, noncurrent	1,989	1,257
Other liabilities	7,511	7,382
Total liabilities	185,631	175,857
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock	0	0
Common stock	991	971
Additional paid-in capital	655,792	624,026
Accumulated other comprehensive loss	(3,792)	(5,197)
Accumulated deficit	(346,942)	(319,720)
Treasury stock at cost (0.5 million shares as of March 31, 2017 and December 31, 2016)	(652)	(652)
Total stockholders’ equity	305,397	299,428
Total liabilities and stockholders’ equity	$ 491,028	$ 475,285

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands, shares in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 2,264	$ 1,269
Treasury stock, shares (in shares)	0.5	0.5

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue		$ 93,007	$ 68,459
Cost of revenue	[1]	28,107	21,516
Gross profit		64,900	46,943
Operating expenses:
Research and development	[1]	26,456	21,597
Sales and marketing	[1]	47,301	36,172
General and administrative	[1]	18,317	15,861
Total operating expenses	[1]	92,074	73,630
Operating loss		(27,174)	(26,687)
Other income (expense), net		218	(70)
Loss before provision for income taxes		(26,956)	(26,757)
Provision for income taxes		38	414
Net loss		$ (26,994)	$ (27,171)
Net loss per share, basic and diluted (usd per share)		$ (0.28)	$ (0.30)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)		97,475	90,519
[1]	(1) Includes share-based compensation expense as follows: Three Months EndedMarch 31,2017 2016Cost of revenue$2,104 $1,633Research and development6,914 6,627Sales and marketing5,633 5,439General and administrative4,562 3,996

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based compensation expense	$ 19,213	$ 17,695
Cost of revenue
Share-based compensation expense	2,104	1,633
Research and development
Share-based compensation expense	6,914	6,627
Sales and marketing
Share-based compensation expense	5,633	5,439
General and administrative
Share-based compensation expense	$ 4,562	$ 3,996

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (26,994)	$ (27,171)
Other comprehensive gain, before tax:
Net change in unrealized gain on available-for-sale investments	119	129
Foreign currency translation gain	576	733
Net change in unrealized loss on derivative instruments	1,526	2,610
Other comprehensive gain, before tax	2,221	3,472
Tax effect	(816)	0
Other comprehensive gain, net of tax	1,405	3,472
Comprehensive loss	$ (25,589)	$ (23,699)

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net loss	$ (26,994)	$ (27,171)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization	7,923	6,526
Share-based compensation	19,213	17,695
Other	697	403
Changes in operating assets and liabilities:
Accounts receivable	(2,316)	1,898
Prepaid expenses and other current assets	(513)	862
Other assets and liabilities	(332)	(383)
Accounts payable	1,958	(1,851)
Accrued liabilities	2,524	2,307
Accrued compensation and related benefits	(2,596)	(2,066)
Deferred revenue	7,585	6,369
Net cash provided by operating activities	7,149	4,589
Cash flows from investing activities
Purchases of property and equipment	(4,791)	(3,249)
Internal-use software development costs	(1,852)	(1,351)
Purchases of marketable securities	(40,758)	(20,795)
Proceeds from maturities of marketable securities	31,654	10,051
Proceeds from sale of marketable securities	8,602	7,604
Net cash used in investing activities	(7,145)	(7,740)
Cash flows from financing activities
Proceeds from exercise of employee stock options	11,689	1,915
Proceeds from employee stock purchase plan	3,844	3,144
Taxes paid related to net share settlement of equity awards	(154)	(189)
Net cash provided by financing activities	15,379	4,870
Effect of exchange rate changes on cash and cash equivalents	198	(154)
Net increase in cash and cash equivalents	15,581	1,565
Cash and cash equivalents at beginning of period	93,677	216,226
Cash and cash equivalents at end of period	109,258	217,791
Supplemental cash flow data:
Cash paid for interest and income taxes	196	168
Non-cash investing and financing activities:
Vesting of early exercised stock options	115	232
Balance of property and equipment in accounts payable and accrued expenses	1,460	2,345
Share-based compensation capitalized in internal-use software development costs	$ 694	$ 563

Overview and Basis of Presentat

Overview and Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview and Basis of Presentation	Note 1. Overview and Basis of Presentation Company and Background Zendesk was founded in Denmark in 2007 and reincorporated in Delaware in April 2009 . We are a software development company that provides software as a service, or SaaS, products that are intended to help organizations and their customers build better relationships. With our origins in customer service, we have evolved our offerings over time to a family of products that work together to help organizations understand their customers, improve communications, and engage where and when it’s needed most. Our product family is built upon a modern architecture that enables us and our customers to rapidly innovate, adapt our technology in novel ways, and easily integrate with other products and applications. References to Zendesk, the “Company”, “our”, or “we” in these notes refer to Zendesk, Inc. and its subsidiaries on a consolidated basis. Basis of Presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or GAAP, and applicable rules and regulations of the Securities and Exchange Commission, or SEC, regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2016, filed on February 27, 2017. There have been no changes to our significant accounting policies described in the Annual Report on Form 10-K that have had a material impact on our condensed consolidated financial statements and related notes, except as described below. In the first quarter of 2017, we changed our accounting policy for share-based compensation to recognize forfeitures as they occur, as permitted by Accounting Standards Update, or ASU, 2016-09. Refer to Recently Issued and Adopted Accounting Pronouncements below for a more detailed discussion. The consolidated balance sheet as of December 31, 2016 included herein was derived from the audited financial statements as of that date. The unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, our comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year ending December 31, 2017 . Use of Estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reported periods. Significant items subject to such estimates and assumptions include the fair value of share-based awards, acquired intangible assets, goodwill and unrecognized tax benefits, the useful lives of acquired intangible assets and property and equipment, the capitalization and estimated useful life of capitalized internal-use software, and financial forecasts used in currency hedging. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates. Concentrations of Risk As of March 31, 2017 , no customers represented 10% or greater of our total accounts receivable balance. There were no customers that individually exceeded 10% of our revenue during the three months ended March 31, 2017 or 2016 . Recently Issued and Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or the FASB, issued new revenue guidance that provides principles for recognizing revenue to which an entity expects to be entitled for the transfer of promised goods or services to customers. As currently issued and amended, the new guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, though early adoption is permitted for annual reporting periods beginning after December 15, 2016. The guidance may be applied retrospectively to each prior period presented (full retrospective method), or with the cumulative effect recognized as of the date of initial adoption (modified retrospective method). We currently intend to adopt using the full retrospective approach, however our decision has not been finalized. We continue to assess the impact of the new guidance on our existing revenue arrangements. As a result of adoption, we also expect to capitalize a significant portion of our sales commissions and other incremental costs to acquire contracts, which we historically expensed as incurred, which will result in an increase in deferred costs recognized on our balance sheet. We have not yet concluded the useful life of our capitalized costs, which will affect the classification and magnitude of the deferred costs at each reporting period. We continue to quantify the effect of these changes on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, regarding ASC Topic 842 “ Leases. ” This new standard requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets and eliminates certain real estate-specific provisions. The new guidance is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. Early adoption is permitted. We are currently evaluating the effect of this standard on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, regarding ASC Topic 718 “ Compensation - Stock Compensation. ” This amendment changes certain aspects of accounting for share-based awards to employees, including the recognition of income tax effects of awards when the awards vest or are settled, requirements on net share settlement to cover tax withholding, and accounting for forfeitures. We adopted the standard in the first quarter of 2017. As required by the new standard, we now recognize excess tax effects from share-based awards as a component of provision for income taxes in our statement of operations when awards vest or are settled. Upon adoption, we recorded a deferred tax asset of $52.8 million to reflect, on a modified retrospective basis, the previously unrecognized excess tax benefits, however the deferred tax asset was fully offset by a valuation allowance, resulting in no impact to our consolidated financial statements. In our statement of cash flows, we no longer classify excess tax benefits as a reduction from operating cash flows. This change was made prospectively beginning with the quarter ended March 31, 2017. We also elected to account for forfeitures as they occur, therefore share-based compensation expense for the three months ended March 31, 2017 has been calculated based on actual forfeitures in our consolidated statement of operations, rather than our previous approach which was net of estimated forfeitures. The cumulative-effect adjustment of this change on a modified retrospective basis was not material. Share-based compensation expense for the three months ended March 31, 2016 was recorded net of estimated forfeitures. In October 2016, the FASB issued ASU 2016-16, “ Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, ” which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual reporting period. The new standard must be adopted using a modified retrospective basis, with the cumulative effect recognized as of the date of adoption. We adopted the standard in the first quarter of 2017. Upon adoption, we recorded a deferred tax asset of $6.2 million to reflect the previously unrecognized tax benefits, however the deferred tax asset was fully offset by a valuation allowance, resulting in no impact to our consolidated financial statements.

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Financial Instruments	Note 2. Financial Instruments Investments The following tables present information about our financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 based on the three-tier fair value hierarchy (in thousands): Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 131,527 $ 131,527 U.S. treasury securities 30,564 30,564 Asset-backed securities — 30,399 30,399 Agency securities 8,485 8,485 Commercial paper — 5,785 5,785 Money market funds 3,825 — 3,825 Total $ 3,825 $ 206,760 $ 210,585 Included in cash and cash equivalents $ 3,825 Included in marketable securities $ 206,760 Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 124,930 $ 124,930 Asset-backed securities 32,567 32,567 U.S. treasury securities 30,585 30,585 Commercial paper 9,787 9,787 Agency securities 8,489 8,489 Money market funds 3,545 $ — $ 3,545 Total $ 3,545 $ 206,358 $ 209,903 Included in cash and cash equivalents $ 3,545 Included in marketable securities $ 206,358 As of March 31, 2017 and December 31, 2016 , there were no securities within Level 3 of the fair value hierarchy. There were no transfers between fair value measurement levels during the three months ended March 31, 2017 . Gross unrealized gains and losses for cash equivalents and marketable securities as of March 31, 2017 and December 31, 2016 were no t material. As of March 31, 2017 and December 31, 2016 , there were no securities that were in an unrealized loss position for more than 12 months . The following table classifies our marketable securities by contractual maturity as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Due in one year or less $ 138,440 $ 131,190 Due after one year 68,320 75,168 Total $ 206,760 $ 206,358 For certain other financial instruments, including accounts receivable, accounts payable and other current liabilities, the carrying amounts approximate their fair value due to the relatively short maturity of these balances. Derivative Instruments and Hedging Our foreign currency exposures typically arise from expenditures associated with foreign operations and sales in foreign currencies for subscriptions to our products. In September 2015, we implemented a hedging program to mitigate the effect of foreign currency fluctuations on our future cash flows and earnings. We enter into foreign currency forward contracts with certain financial institutions and designate those contracts as cash flow hedges. Our foreign currency forward contracts generally have maturities of 15 months or less. As of March 31, 2017 , the balance of accumulated other comprehensive loss included an unrealized loss of $1.5 million related to the effective portion of changes in the fair value of foreign currency forward contracts designated as cash flow hedges. We expect to reclassify $1.5 million from accumulated other comprehensive loss into earnings over the next 12 months associated with our cash flow hedges. The following tables present information about our derivative instruments on our consolidated balance sheets as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value (Level 2) Balance Sheet Location Fair Value (Level 2) Foreign currency forward contracts Other current assets $ 729 Accrued liabilities $ 2,740 Total $ 729 $ 2,740 December 31, 2016 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value (Level 2) Balance Sheet Location Fair Value (Level 2) Foreign currency forward contracts Other current assets $ 868 Accrued liabilities $ 4,280 Total $ 868 $ 4,280 Our foreign currency forward contracts had a total notional value of $81.3 million and $79.6 million as of March 31, 2017 and December 31, 2016 , respectively. We have a master netting arrangement with each of our counterparties, which permits net settlement of multiple, separate derivative contracts with a single payment. We may also be required to exchange cash collateral with certain of our counterparties on a regular basis. ASC 815 permits companies to present the fair value of derivative instruments on a net basis according to master netting arrangements. We have elected to present our derivative instruments on a gross basis in our consolidated financial statements. As of March 31, 2017 and December 31, 2016 , our balances of cash collateral posted with counterparties were none and $1.1 million , respectively. The following table presents information about our derivative instruments on the statement of operations for the three months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Hedging Instrument Location of Loss Reclassified into Earnings Gain Recognized in AOCI Loss Reclassified from AOCI into Earnings Gain Recognized in AOCI Loss Reclassified from AOCI into Earnings Foreign currency forward contracts Revenue, cost of revenue, operating expenses $ 993 $ (533 ) $ 2,348 $ (262 ) Total $ 993 $ (533 ) $ 2,348 $ (262 ) All derivatives have been designated as hedging instruments. Amounts recognized in earnings related to excluded time value and hedge ineffectiveness for the three months ended March 31, 2017 and 2016 were not material .

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Note 3. Property and Equipment Property and equipment, net consists of the following (in thousands): March 31, December 31, Hosting equipment $ 36,410 $ 35,018 Leasehold improvements 26,727 25,396 Capitalized internal-use software 26,553 25,773 Computer equipment and software 12,766 11,879 Furniture and fixtures 8,752 8,014 Construction in progress 7,168 7,993 Total 118,376 114,073 Less: accumulated depreciation and amortization (57,534 ) (51,342 ) Property and equipment, net $ 60,842 $ 62,731 Depreciation expense was $4.8 million and $3.7 million for the three months ended March 31, 2017 and 2016 , respectively. Amortization expense of capitalized internal-use software totaled $2.1 million and $1.7 million for the three months ended March 31, 2017 and 2016 , respectively. The carrying value of capitalized internal-use software at March 31, 2017 and December 31, 2016 was $15.7 million and $15.4 million , respectively, including $6.7 million and $5.4 million in construction in progress, respectively.

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Acquired Intangible Assets	Note 4. Goodwill and Acquired Intangible Assets The changes in the carrying amount of goodwill for the three months ended March 31, 2017 are as follows (in thousands): Balance as of December 31, 2016 $ 45,347 Foreign currency translation adjustments 297 Balance as of March 31, 2017 $ 45,644 Acquired intangible assets subject to amortization as of March 31, 2017 and December 31, 2016 consist of the following (in thousands): As of March 31, 2017 Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Remaining Useful Life (In years) Developed technology $ 14,000 $ (7,433 ) $ (122 ) $ 6,445 2.8 Customer relationships 1,800 (1,151 ) (39 ) 610 2.1 $ 15,800 $ (8,584 ) $ (161 ) $ 7,055 As of December 31, 2016 Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Remaining Useful Life (In years) Developed technology $ 14,000 $ (6,584 ) $ (169 ) $ 7,247 2.9 Customer relationships 1,800 (1,044 ) (53 ) 703 2.3 $ 15,800 $ (7,628 ) $ (222 ) $ 7,950 Amortization expense of acquired intangible assets for each of the three months ended March 31, 2017 and 2016 was $0.9 million . Estimated future amortization expense as of March 31, 2017 is as follows (in thousands): Remainder of 2017 $ 2,349 2018 2,128 2019 2,066 2020 512 $ 7,055

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 5. Commitments and Contingencies Leases We lease office space under noncancelable operating leases with various expiration dates. Certain of the office space lease agreements contain rent holidays or rent escalation provisions. Rent holiday and rent escalation provisions are considered in determining the straight-line expense to be recorded over the lease term. The lease term begins on the date of initial possession of the leased property for purposes of recognizing lease expense on a straight-line basis over the term of the lease. Rent expense was $2.7 million and $2.2 million for the three months ended March 31, 2017 and 2016 , respectively. In April 2017, we entered into an operating lease agreement for approximately 58,000 square feet of office space in Dublin, Ireland. The lease is expected to commence on October 3, 2017 and has a noncancelable term of 12 years . The total anticipated amount of rent to be paid over the noncancelable term of the lease is approximately $37.0 million . In addition to monthly rent obligations, we are responsible for certain operating costs and taxes associated with the leased premises. Litigation and Loss Contingencies We accrue estimates for resolution of legal and other contingencies when losses are probable and estimable. From time to time, we may become a party to litigation and subject to claims that arise in the ordinary course of business, including intellectual property claims, labor and employment claims, threatened claims, breach of contract claims, tax, and other matters. We currently have no material pending litigation. We are not currently aware of any litigation matters or loss contingencies that would be expected to have a material adverse effect on our business, consolidated balance sheets, results of operations, comprehensive loss, or cash flows. Indemnifications In the ordinary course of business, we enter into contractual arrangements under which we agree to provide indemnification of varying scope and terms to customers, business partners and other parties with respect to certain matters, including, but not limited to, losses arising out of the breach of such agreements, intellectual property infringement claims made by third parties, and other liabilities relating to or arising from our products or our acts or omissions. In these circumstances, payment may be conditional on the other party making a claim pursuant to the procedures specified in the particular contract. Further, our obligations under these agreements may be limited in terms of time and/or amount, and in some instances, we may have recourse against third parties for certain payments. In addition, we have indemnification agreements with our directors and executive officers that require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The terms of such obligations may vary. To date, we have not incurred any material costs, and we have not accrued any liabilities in our consolidated financial statements, as a result of these obligations. Certain of our product offerings include service-level agreements warranting defined levels of uptime reliability and performance, which permit those customers to receive credits for future services in the event that we fail to meet those levels. To date, we have not accrued for any significant liabilities in our condensed consolidated financial statements as a result of these service-level agreements.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Common Stock and Stockholders' Equity	Note 6. Common Stock and Stockholders’ Equity Common Stock As of March 31, 2017 and December 31, 2016 , there were 400 million shares authorized for issuance with a par value of $0.01 per share. There were 99.2 million and 97.2 million shares of common stock issued and 98.7 million and 96.7 million shares outstanding as of March 31, 2017 and December 31, 2016 , respectively. Included within the number of shares issued and outstanding were approximately 41 thousand and 0.1 million shares of common stock subject to repurchase, as of March 31, 2017 and December 31, 2016 , respectively. Preferred Stock As of each of March 31, 2017 and December 31, 2016 , 10.0 million shares of preferred stock were authorized for issuance with a par value of $0.01 per share and no shares of preferred stock were issued or outstanding. Employee Equity Plans Employee Stock Purchase Plan Under our Employee Stock Purchase Plan, or ESPP, eligible employees are granted options to purchase shares of our common stock through payroll deductions. The ESPP provides for 18-month offering periods, which include three six-month purchase periods. At the end of each purchase period, employees are able to purchase shares at 85% of the lower of the fair market value of our common stock at the beginning of an offering period or the fair market value of our common stock at the end of the purchase period. No shares of common stock were purchased under the ESPP during the three months ended March 31, 2017 . Pursuant to the terms of the ESPP, the number of shares reserved under the ESPP increased by 1.0 million shares on January 1, 2017. As of March 31, 2017 , 4.2 million shares of common stock were available for issuance under the ESPP. Stock Option and Grant Plans Our board of directors adopted the 2009 Stock Option and Grant Plan, or the 2009 Plan, in July 2009. The 2009 Plan was terminated in connection with our IPO in May 2014, and accordingly, no shares are available for issuance under this plan. The 2009 Plan continues to govern outstanding awards granted thereunder. Our 2014 Stock Option and Incentive Plan, or the 2014 Plan, serves as the successor to our 2009 Plan. Pursuant to the terms of the 2014 Plan, the number of shares reserved for issuance under the 2014 Plan increased by 4.8 million shares on January 1, 2017. As of March 31, 2017 , we had 10.3 million shares of common stock available for future grants under the 2014 Plan. On May 6, 2016, the compensation committee of our board of directors granted equity awards representing 1.2 million shares. These awards were granted outside of the 2014 Plan pursuant to an exemption provided for “employment inducement awards” within the meaning of Section 303A.08 of the New York Stock Exchange Listed Company Manual and accordingly did not require approval from our stockholders. A summary of our stock option and RSU activity for the three months ended March 31, 2017 is as follows (in thousands, except per share information): Options Outstanding RSUs Outstanding Shares Available for Grant Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding RSUs Weighted Average Grant Date Fair Value (In years) Outstanding — January 1, 2017 6,039 8,479 $ 14.52 7.49 $ 66,449 6,936 $ 20.81 Increase in authorized shares 4,833 Stock options granted (170 ) 170 24.51 RSUs granted (892 ) 892 24.64 Stock options exercised (1,114 ) 10.49 RSUs vested (930 ) 17.34 Stock options forfeited or canceled 156 (156 ) 23.33 RSUs forfeited or canceled 381 (381 ) 22.29 Outstanding — March 31, 2017 10,347 7,379 $ 15.17 7.39 $ 95,123 6,517 $ 21.74 The aggregate intrinsic value for options outstanding represents the difference between the closing stock price of our common stock and the exercise price of outstanding, in-the-money options. Our closing stock price as reported on the New York Stock Exchange as of March 31, 2017 was $28.04 . As of March 31, 2017 , we had a total of $168.5 million in future share-based compensation expense related to all equity awards to be recognized over a weighted average period of 2.6 years. Early Exercise of Stock Options and Purchase of Unvested Stock Awards Common stock purchased pursuant to an early exercise of stock options or unvested stock awards is not deemed to be outstanding for financial reporting purposes until those shares vest. As of March 31, 2017 and December 31, 2016 , there were approximately 41 thousand and 0.1 million shares, outstanding as a result of early exercise of stock options and purchase of unvested stock awards by our employees and directors that were classified as accrued liabilities for an aggregated amount of $0.3 million and $0.4 million , respectively.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	Note 7. Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including outstanding share-based awards, to the extent dilutive. Basic and diluted net loss per share were the same for each period presented as the inclusion of all potential common stock outstanding would have been anti-dilutive. The following table presents the calculation of basic and diluted net loss per share for the periods presented (in thousands, except per share data): Three Months Ended 2017 2016 Net loss $ (26,994 ) $ (27,171 ) Weighted-average shares used to compute basic and diluted net loss per share 97,475 90,519 Net loss per share, basic and diluted $ (0.28 ) $ (0.30 ) The anti-dilutive securities excluded from the shares used to calculate diluted net loss per share are as follows (in thousands): As of March 31, 2017 2016 Shares subject to outstanding common stock options and employee stock purchase plan 7,647 10,500 Restricted stock units 6,517 6,967 14,164 17,467

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 8. Income Taxes Our effective tax rates for the three months ended March 31, 2017 and 2016 were less than 2% . The effective tax rates differ from the statutory rate primarily as a result of not recognizing a deferred tax asset for U.S. losses due to having a full valuation allowance against U.S. deferred tax assets.

Geographic Information

Geographic Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Geographic Information	Note 9. Geographic Information Our chief operating decision maker reviews the financial information presented on a consolidated basis for purposes of allocating resources and evaluating our financial performance. Accordingly, we have determined that we operate in a single reporting segment. Revenue The following table presents our revenue by geographic area, as determined based on the billing address of our customers (in thousands): Three Months Ended 2017 2016 United States $ 50,224 $ 37,567 EMEA 26,042 18,831 Other 16,741 12,061 Total $ 93,007 $ 68,459 Long-Lived Assets The following table presents our long-lived assets by geographic area (in thousands): As of As of United States $ 24,964 $ 26,372 EMEA: Republic of Ireland 5,317 5,703 Other EMEA 6,375 6,834 Total EMEA 11,692 12,537 APAC 8,449 8,357 Total $ 45,105 $ 47,266 The carrying values of capitalized internal-use software and intangible assets are excluded from the balance of long-lived assets presented in the table above.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Event On April 27, 2017, we completed the acquisition of Outbound Solutions, Inc., which provides software that allows companies to deliver intelligent, behavior-based messages across multiple channels, for cash consideration. The acquisition will be accounted for as a business combination. We are in the process of evaluating the impact of the business combination on our consolidated financial statements.

Overview and Basis of Present18

Overview and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or GAAP, and applicable rules and regulations of the Securities and Exchange Commission, or SEC, regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2016, filed on February 27, 2017. There have been no changes to our significant accounting policies described in the Annual Report on Form 10-K that have had a material impact on our condensed consolidated financial statements and related notes, except as described below. In the first quarter of 2017, we changed our accounting policy for share-based compensation to recognize forfeitures as they occur, as permitted by Accounting Standards Update, or ASU, 2016-09. Refer to Recently Issued and Adopted Accounting Pronouncements below for a more detailed discussion. The consolidated balance sheet as of December 31, 2016 included herein was derived from the audited financial statements as of that date. The unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, our comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year ending December 31, 2017 .
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reported periods. Significant items subject to such estimates and assumptions include the fair value of share-based awards, acquired intangible assets, goodwill and unrecognized tax benefits, the useful lives of acquired intangible assets and property and equipment, the capitalization and estimated useful life of capitalized internal-use software, and financial forecasts used in currency hedging. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or the FASB, issued new revenue guidance that provides principles for recognizing revenue to which an entity expects to be entitled for the transfer of promised goods or services to customers. As currently issued and amended, the new guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, though early adoption is permitted for annual reporting periods beginning after December 15, 2016. The guidance may be applied retrospectively to each prior period presented (full retrospective method), or with the cumulative effect recognized as of the date of initial adoption (modified retrospective method). We currently intend to adopt using the full retrospective approach, however our decision has not been finalized. We continue to assess the impact of the new guidance on our existing revenue arrangements. As a result of adoption, we also expect to capitalize a significant portion of our sales commissions and other incremental costs to acquire contracts, which we historically expensed as incurred, which will result in an increase in deferred costs recognized on our balance sheet. We have not yet concluded the useful life of our capitalized costs, which will affect the classification and magnitude of the deferred costs at each reporting period. We continue to quantify the effect of these changes on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, regarding ASC Topic 842 “ Leases. ” This new standard requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets and eliminates certain real estate-specific provisions. The new guidance is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. Early adoption is permitted. We are currently evaluating the effect of this standard on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, regarding ASC Topic 718 “ Compensation - Stock Compensation. ” This amendment changes certain aspects of accounting for share-based awards to employees, including the recognition of income tax effects of awards when the awards vest or are settled, requirements on net share settlement to cover tax withholding, and accounting for forfeitures. We adopted the standard in the first quarter of 2017. As required by the new standard, we now recognize excess tax effects from share-based awards as a component of provision for income taxes in our statement of operations when awards vest or are settled. Upon adoption, we recorded a deferred tax asset of $52.8 million to reflect, on a modified retrospective basis, the previously unrecognized excess tax benefits, however the deferred tax asset was fully offset by a valuation allowance, resulting in no impact to our consolidated financial statements. In our statement of cash flows, we no longer classify excess tax benefits as a reduction from operating cash flows. This change was made prospectively beginning with the quarter ended March 31, 2017. We also elected to account for forfeitures as they occur, therefore share-based compensation expense for the three months ended March 31, 2017 has been calculated based on actual forfeitures in our consolidated statement of operations, rather than our previous approach which was net of estimated forfeitures. The cumulative-effect adjustment of this change on a modified retrospective basis was not material. Share-based compensation expense for the three months ended March 31, 2016 was recorded net of estimated forfeitures. In October 2016, the FASB issued ASU 2016-16, “ Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, ” which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual reporting period. The new standard must be adopted using a modified retrospective basis, with the cumulative effect recognized as of the date of adoption. We adopted the standard in the first quarter of 2017. Upon adoption, we recorded a deferred tax asset of $6.2 million to reflect the previously unrecognized tax benefits, however the deferred tax asset was fully offset by a valuation allowance, resulting in no impact to our consolidated financial statements.

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value on Recurring Basis	The following tables present information about our financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 based on the three-tier fair value hierarchy (in thousands): Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 131,527 $ 131,527 U.S. treasury securities 30,564 30,564 Asset-backed securities — 30,399 30,399 Agency securities 8,485 8,485 Commercial paper — 5,785 5,785 Money market funds 3,825 — 3,825 Total $ 3,825 $ 206,760 $ 210,585 Included in cash and cash equivalents $ 3,825 Included in marketable securities $ 206,760 Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 124,930 $ 124,930 Asset-backed securities 32,567 32,567 U.S. treasury securities 30,585 30,585 Commercial paper 9,787 9,787 Agency securities 8,489 8,489 Money market funds 3,545 $ — $ 3,545 Total $ 3,545 $ 206,358 $ 209,903 Included in cash and cash equivalents $ 3,545 Included in marketable securities $ 206,358
Schedule of Marketable Securities Classified by Contractual Maturity	The following table classifies our marketable securities by contractual maturity as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Due in one year or less $ 138,440 $ 131,190 Due after one year 68,320 75,168 Total $ 206,760 $ 206,358
Schedule of Derivative Instruments on Consolidated Balance Sheets	The following tables present information about our derivative instruments on our consolidated balance sheets as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value (Level 2) Balance Sheet Location Fair Value (Level 2) Foreign currency forward contracts Other current assets $ 729 Accrued liabilities $ 2,740 Total $ 729 $ 2,740 December 31, 2016 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value (Level 2) Balance Sheet Location Fair Value (Level 2) Foreign currency forward contracts Other current assets $ 868 Accrued liabilities $ 4,280 Total $ 868 $ 4,280
Schedule of Derivative Instruments on Statement of Operations	The following table presents information about our derivative instruments on the statement of operations for the three months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Hedging Instrument Location of Loss Reclassified into Earnings Gain Recognized in AOCI Loss Reclassified from AOCI into Earnings Gain Recognized in AOCI Loss Reclassified from AOCI into Earnings Foreign currency forward contracts Revenue, cost of revenue, operating expenses $ 993 $ (533 ) $ 2,348 $ (262 ) Total $ 993 $ (533 ) $ 2,348 $ (262 )

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Components of Property and Equipment	Property and equipment, net consists of the following (in thousands): March 31, December 31, Hosting equipment $ 36,410 $ 35,018 Leasehold improvements 26,727 25,396 Capitalized internal-use software 26,553 25,773 Computer equipment and software 12,766 11,879 Furniture and fixtures 8,752 8,014 Construction in progress 7,168 7,993 Total 118,376 114,073 Less: accumulated depreciation and amortization (57,534 ) (51,342 ) Property and equipment, net $ 60,842 $ 62,731

Goodwill and Acquired Intangi21

Goodwill and Acquired Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the three months ended March 31, 2017 are as follows (in thousands): Balance as of December 31, 2016 $ 45,347 Foreign currency translation adjustments 297 Balance as of March 31, 2017 $ 45,644
Summary of Intangible Assets Acquired	Acquired intangible assets subject to amortization as of March 31, 2017 and December 31, 2016 consist of the following (in thousands): As of March 31, 2017 Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Remaining Useful Life (In years) Developed technology $ 14,000 $ (7,433 ) $ (122 ) $ 6,445 2.8 Customer relationships 1,800 (1,151 ) (39 ) 610 2.1 $ 15,800 $ (8,584 ) $ (161 ) $ 7,055 As of December 31, 2016 Cost Accumulated Amortization Foreign Currency Translation Adjustments Net Remaining Useful Life (In years) Developed technology $ 14,000 $ (6,584 ) $ (169 ) $ 7,247 2.9 Customer relationships 1,800 (1,044 ) (53 ) 703 2.3 $ 15,800 $ (7,628 ) $ (222 ) $ 7,950
Summary of Estimated Future Amortization Expense	Estimated future amortization expense as of March 31, 2017 is as follows (in thousands): Remainder of 2017 $ 2,349 2018 2,128 2019 2,066 2020 512 $ 7,055

Common Stock and Stockholders22

Common Stock and Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Summary of Stock Option and RSU Award Activity	A summary of our stock option and RSU activity for the three months ended March 31, 2017 is as follows (in thousands, except per share information): Options Outstanding RSUs Outstanding Shares Available for Grant Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding RSUs Weighted Average Grant Date Fair Value (In years) Outstanding — January 1, 2017 6,039 8,479 $ 14.52 7.49 $ 66,449 6,936 $ 20.81 Increase in authorized shares 4,833 Stock options granted (170 ) 170 24.51 RSUs granted (892 ) 892 24.64 Stock options exercised (1,114 ) 10.49 RSUs vested (930 ) 17.34 Stock options forfeited or canceled 156 (156 ) 23.33 RSUs forfeited or canceled 381 (381 ) 22.29 Outstanding — March 31, 2017 10,347 7,379 $ 15.17 7.39 $ 95,123 6,517 $ 21.74

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss per Share	The following table presents the calculation of basic and diluted net loss per share for the periods presented (in thousands, except per share data): Three Months Ended 2017 2016 Net loss $ (26,994 ) $ (27,171 ) Weighted-average shares used to compute basic and diluted net loss per share 97,475 90,519 Net loss per share, basic and diluted $ (0.28 ) $ (0.30 )
Schedule of Anti-Dilutive Securities Excluded from the Diluted per Share Calculation	The anti-dilutive securities excluded from the shares used to calculate diluted net loss per share are as follows (in thousands): As of March 31, 2017 2016 Shares subject to outstanding common stock options and employee stock purchase plan 7,647 10,500 Restricted stock units 6,517 6,967 14,164 17,467

Geographic Information (Tables)

Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of Revenue by Geographic Areas	The following table presents our revenue by geographic area, as determined based on the billing address of our customers (in thousands): Three Months Ended 2017 2016 United States $ 50,224 $ 37,567 EMEA 26,042 18,831 Other 16,741 12,061 Total $ 93,007 $ 68,459
Schedule of Long-Lived Assets by Geographic Areas	The following table presents our long-lived assets by geographic area (in thousands): As of As of United States $ 24,964 $ 26,372 EMEA: Republic of Ireland 5,317 5,703 Other EMEA 6,375 6,834 Total EMEA 11,692 12,537 APAC 8,449 8,357 Total $ 45,105 $ 47,266

Overview and Basis of Present25

Overview and Basis of Presentation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Subsidiary, Sale of Stock [Line Items]
Year founded	2,007
Reincorporated date	Apr. 30, 2009
Deferred tax asset related to stock compensation	$ 52.8
Accounting Standards Update 2016-16 | Adjustments for New Accounting Principle, Early Adoption
Subsidiary, Sale of Stock [Line Items]
Deferred tax asset related to intra-entity transfers of assets	$ 6.2
Customer Concentration Risk | Accounts Receivable
Subsidiary, Sale of Stock [Line Items]
Percentage of total revenue or receivables, floor	10.00%
Customer Concentration Risk | Sales Revenue, Net
Subsidiary, Sale of Stock [Line Items]
Percentage of total revenue or receivables, floor	10.00%	10.00%

Financial Instruments - Financi

Financial Instruments - Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Included in marketable securities	$ 206,760	$ 206,358
Fair Value Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	210,585	209,903
Included in cash and cash equivalents	3,825	3,545
Included in marketable securities	206,760	206,358
Fair Value Measurements, Recurring | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	131,527	124,930
Fair Value Measurements, Recurring | U.S. treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	30,564	30,585
Fair Value Measurements, Recurring | Asset-backed securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	30,399	32,567
Fair Value Measurements, Recurring | Agency securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	8,485	8,489
Fair Value Measurements, Recurring | Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	5,785	9,787
Fair Value Measurements, Recurring | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	3,825	3,545
Fair Value Measurements, Recurring | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	3,825	3,545
Fair Value Measurements, Recurring | Level 1 | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0	0
Fair Value Measurements, Recurring | Level 1 | Asset-backed securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0
Fair Value Measurements, Recurring | Level 1 | Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0
Fair Value Measurements, Recurring | Level 1 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	3,825	3,545
Fair Value Measurements, Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	206,760	206,358
Fair Value Measurements, Recurring | Level 2 | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	131,527	124,930
Fair Value Measurements, Recurring | Level 2 | U.S. treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	30,564	30,585
Fair Value Measurements, Recurring | Level 2 | Asset-backed securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	30,399	32,567
Fair Value Measurements, Recurring | Level 2 | Agency securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	8,485	8,489
Fair Value Measurements, Recurring | Level 2 | Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	5,785	9,787
Fair Value Measurements, Recurring | Level 2 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	$ 0	$ 0

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities that were in an unrealized loss position for more than 12 months.	$ 0	$ 0
Cash collateral posted	$ 0	1,100,000
Foreign currency forward contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative, maturity	15 months
Unrealized loss in accumulated other comprehensive loss	$ 1,500,000
Reclassification from accumulated other comprehensive income into earnings over next 12 month	1,500,000
Notional value	81,300,000	79,600,000
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities within Level 3 of the fair value hierarchy	$ 0	$ 0

Financial Instruments - Marketa

Financial Instruments - Marketable Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Due in one year or less	$ 138,440	$ 131,190
Due after one year	68,320	75,168
Total	$ 206,760	$ 206,358

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments on Consolidated Balance Sheets (Details) - Designated as Hedging Instrument - Level 2 - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 729	$ 868
Liability Derivatives, Fair Value	2,740	4,280
Foreign currency forward contracts | Other current assets
Derivatives Fair Value [Line Items]
Asset Derivatives, Fair Value	729	868
Foreign currency forward contracts | Accrued liabilities
Derivatives Fair Value [Line Items]
Liability Derivatives, Fair Value	$ 2,740	$ 4,280

Financial Instruments - Sched30

Financial Instruments - Schedule of Derivative Instruments on Statement of Operations (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments Gain Loss [Line Items]
Gain Recognized in AOCI	$ 993	$ 2,348
Loss Reclassified from AOCI into Earnings	(533)	(262)
Revenue, cost of revenue, operating expenses | Foreign currency forward contracts
Derivative Instruments Gain Loss [Line Items]
Gain Recognized in AOCI	993	$ 2,348
Loss Reclassified from AOCI into Earnings	$ (533)

Property and Equipment - Compon

Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 118,376	$ 114,073
Less: accumulated depreciation and amortization	(57,534)	(51,342)
Property and equipment, net	60,842	62,731
Hosting equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	36,410	35,018
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	26,727	25,396
Capitalized internal-use software
Property Plant And Equipment [Line Items]
Property and equipment, gross	26,553	25,773
Computer equipment and software
Property Plant And Equipment [Line Items]
Property and equipment, gross	12,766	11,879
Furniture and fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,752	8,014
Construction in progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 7,168	$ 7,993

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 4.8	$ 3.7
Amortization expense of capitalized internal-use software	2.1	$ 1.7
Carrying value of capitalized internal-use software	15.7		$ 15.4
Capitalized internal-use software included in construction in progress	$ 6.7		$ 5.4

Goodwill and Acquired Intangi33

Goodwill and Acquired Intangible Assets - Changes in Carrying Amount of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2016	$ 45,347
Foreign currency translation adjustments	297
Balance as of March 31, 2017	$ 45,644

Goodwill and Acquired Intangi34

Goodwill and Acquired Intangible Assets - Acquired Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Cost	$ 15,800	$ 15,800
Accumulated Amortization	(8,584)	(7,628)
Foreign Currency Translation Adjustments	(161)	(222)
Net	7,055	7,950
Developed technology
Finite Lived Intangible Assets [Line Items]
Cost	14,000	14,000
Accumulated Amortization	(7,433)	(6,584)
Foreign Currency Translation Adjustments	(122)	(169)
Net	$ 6,445	$ 7,247
Remaining Useful Life	2 years 9 months 18 days	2 years 10 months 24 days
Customer relationships
Finite Lived Intangible Assets [Line Items]
Cost	$ 1,800	$ 1,800
Accumulated Amortization	(1,151)	(1,044)
Foreign Currency Translation Adjustments	(39)	(53)
Net	$ 610	$ 703
Remaining Useful Life	2 years 1 month 6 days	2 years 3 months 2 days

Goodwill and Acquired Intangi35

Goodwill and Acquired Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 0.9	$ 0.9

Goodwill and Acquired Intangi36

Goodwill and Acquired Intangible Assets - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2017	$ 2,349
2,018	2,128
2,019	2,066
2,020	512
Net	$ 7,055	$ 7,950

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) ft² in Thousands, $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2017USD ($)ft²	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Other Commitments [Line Items]
Rent expense		$ 2.7	$ 2.2
Subsequent Event
Other Commitments [Line Items]
Square feet of office space | ft²	58
Term of lease	12 years
Total amount of rent to be paid	$ 37

Common Stock and Stockholders38

Common Stock and Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2017	May 06, 2016	Mar. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)			400,000,000	400,000,000
Common stock, par value (usd per share)			$ 0.01	$ 0.01
Common stock, shares issued (in shares)			99,200,000	97,200,000
Common stock, shares outstanding (in shares)			98,700,000	96,700,000
Common stock shares outstanding, subject to repurchase (in shares)			0	100,000
Preferred stock, shares authorized (in shares)			10,000,000	10,000,000
Preferred stock, par value (usd per share)			$ 0.01	$ 0.01
Preferred stock, shares issued (in shares)			0	0
Preferred stock, shares outstanding (in shares)			0	0
Increase in authorized shares (in shares), shares			4,833,000
Shares of common stock available for issuance (in shares)			10,347,000	6,039,000
Stock options granted (in shares)		1,200,000	170,000
Share price (usd per share)			$ 28.04
Future period share-based compensation expense			$ 168.5
Future period share-based compensation expense, period to recognized			2 years 7 months 6 days
Shares outstanding as a result of early exercise of stock options and purchase of unvested stock awards (in shares)			41,000	100,000
Accrued liability for shares outstanding as a result of early exercise of stock options and purchase of unvested stock awards			$ 0.3	$ 0.4
Employee Stock Purchase Plan Awards [Member]
Class Of Stock [Line Items]
Offering period			18 months
2009 Stock Option and Grant Plan
Class Of Stock [Line Items]
Shares of common stock available for issuance (in shares)			0
2014 Plan | Employee Stock Option
Class Of Stock [Line Items]
Increase in authorized shares (in shares), shares	4,800,000
Shares of common stock available for issuance (in shares)			10,300,000
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Percentage of purchase price of shares lower of the fair market value of common stock employees are able to purchase shares			85.00%
Common shares purchased (in shares)			0
Increase in authorized shares (in shares), shares	1,000,000
Shares of common stock available for issuance (in shares)			4,200,000

Common Stock and Stockholders39

Common Stock and Stockholders' Equity - Summary of Stock Option and RSU Award Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	May 06, 2016	Mar. 31, 2017	Dec. 31, 2016
Shares Available for Grant
Outstanding — January 1, 2017		6,039
Increase in authorized shares, shares		4,833
Stock options granted, shares		(170)
RSUs granted, shares		(892)
Stock options forfeited or canceled, shares		156
RSUs forfeited or canceled, shares		381
Outstanding — March 31, 2017		10,347	6,039
Number of Shares
Balance at the beginning of the period, shares		8,479
Stock options granted, shares	1,200	170
Stock options exercised, shares		(1,114)
Stock options forfeited or canceled, shares		(156)
Balance at the end of the period, shares		7,379	8,479
Weighted-Average Exercise Price
Balance at the beginning of the period (usd per share)		$ 14.52
Stock options granted (usd per share)		24.51
Stock options exercised (usd per share)		10.49
Stock options forfeited or canceled (usd per share)		23.33
Balance at the end of the period (usd per share)		$ 15.17	$ 14.52
Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term		7 years 4 months 21 days	7 years 5 months 27 days
Aggregate Intrinsic Value
Aggregate intrinsic value, beginning		$ 66,449
Aggregate intrinsic value, ending		$ 95,123	$ 66,449
RSUs Outstanding
Outstanding RSUs
Balance at the beginning of the period, shares		6,936
RSUs granted, shares		892
RSUs vested, shares		(930)
RSUs forfeited or canceled, shares		(381)
Balance at the end of the period, shares		6,517	6,936
Weighted-Average Grant Date Fair Value
Balance at the beginning of the period (usd per share)		$ 20.81
Weighted average grant date fair value, RSUs granted (usd per share)		24.64
Weighted average grant date fair value, RSUs vested (usd per share)		17.34
Weighted average grant date fair value, RSUs forfeited or canceled (usd per share)		22.29
Balance at the end of the period (usd per share)		$ 21.74	$ 20.81

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Loss per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net loss	$ (26,994)	$ (27,171)
Weighted-average shares used to compute basic and diluted net loss per share	97,475	90,519
Net loss per share:
Basic and diluted (usd per share)	$ (0.28)	$ (0.30)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Anti-Dilutive Securities Excluded from the Diluted per Share Calculation (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	14,164	17,467
Shares subject to outstanding common stock options and employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	7,647	10,500
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	6,517	6,967

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate, percent, less than	2.00%	2.00%

Geographic Information - Additi

Geographic Information - Additional Information (Details)	3 Months Ended
	Mar. 31, 2017segments
Segment Reporting [Abstract]
Number of reportable segments	1

Geographic Information - Schedu

Geographic Information - Schedule of Revenue by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 93,007	$ 68,459
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	50,224	37,567
EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	26,042	18,831
Other
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 16,741	$ 12,061

Geographic Information - Sche45

Geographic Information - Schedule of Long-Lived Assets by Geographic Areas (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	$ 45,105	$ 47,266
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	24,964	26,372
EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	11,692	12,537
Republic of Ireland
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	5,317	5,703
Other EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	6,375	6,834
APAC
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	$ 8,449	$ 8,357