Zendesk (ZEN) 10-Q 1 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-36456
Entity Registrant Name	ZENDESK, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-4411091
Entity Address, Address Line One	989 Market Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94103
City Area Code	415
Local Phone Number	418-7506
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	ZEN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Smaller Reporting Company	false
Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		120,888,142
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001463172
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 532,517	$ 405,430
Marketable securities	421,328	565,593
Accounts receivable, net of allowance for credit losses of $4,702 and $5,787 as of September 30, 2021 and December 31, 2020, respectively	187,460	199,243
Deferred costs	66,282	51,878
Prepaid expenses and other current assets	61,769	53,829
Total current assets	1,269,356	1,275,973
Marketable securities, noncurrent	591,153	428,678
Property and equipment, net	93,523	94,208
Deferred costs, noncurrent	67,448	52,731
Lease right-of-use assets	73,094	84,013
Goodwill and intangible assets, net	198,946	196,218
Other assets	27,720	25,458
Total assets	2,321,240	2,157,279
Current liabilities:
Accounts payable	33,535	15,428
Accrued liabilities	45,401	38,921
Accrued compensation and related benefits	128,280	103,437
Deferred revenue	444,373	378,935
Lease liabilities	20,201	23,533
Current portion of convertible senior notes, net	137,861	132,388
Total current liabilities	809,651	692,642
Convertible senior notes, net	968,188	935,576
Deferred revenue, noncurrent	3,696	4,423
Lease liabilities, noncurrent	66,733	85,275
Other liabilities	4,696	7,532
Total liabilities	1,852,964	1,725,448
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock	0	0
Common stock	1,204	1,174
Additional paid-in capital	1,553,846	1,344,337
Accumulated other comprehensive (loss) income	(8,385)	3,203
Accumulated deficit	(1,078,389)	(916,883)
Total stockholders’ equity	468,276	431,831
Total liabilities and stockholders’ equity	$ 2,321,240	$ 2,157,279

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,702	$ 5,787

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue		$ 346,974	$ 261,926	$ 963,238	$ 746,066
Cost of revenue	[1]	70,226	62,819	197,863	184,036
Gross profit		276,748	199,107	765,375	562,030
Operating expenses:
Research and development	[1]	92,112	64,842	248,721	184,266
Sales and marketing	[1]	172,828	123,737	495,596	369,442
General and administrative	[1]	50,716	38,854	139,667	109,427
Total operating expenses	[1]	315,656	227,433	883,984	663,135
Operating loss		(38,908)	(28,326)	(118,609)	(101,105)
Other income (expense), net:
Interest expense		(14,762)	(14,087)	(43,768)	(29,060)
Loss on early extinguishment of debt		0	0	0	(25,950)
Interest and other income (expense), net		2,386	3,683	8,430	12,750
Total other income (expense), net		(12,376)	(10,404)	(35,338)	(42,260)
Loss before provision for income taxes		(51,284)	(38,730)	(153,947)	(143,365)
Provision for income taxes		3,133	1,973	7,842	4,777
Net loss		$ (54,417)	$ (40,703)	$ (161,789)	$ (148,142)
Net loss per share, basic (in usd per share)		$ (0.45)	$ (0.35)	$ (1.36)	$ (1.29)
Net loss per share, diluted (in usd per share)		$ (0.45)	$ (0.35)	$ (1.36)	$ (1.29)
Weighted-average shares used to compute net loss per share, basic (in shares)		120,164	115,809	119,050	114,653
Weighted-average shares used to compute net loss per share, diluted (in shares)		120,164	115,809	119,050	114,653
[1]	Includes share-based compensation expense as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Cost of revenue $ 5,343 $ 4,831 $ 15,047 $ 15,077 Research and development 17,189 13,921 49,886 39,076 Sales and marketing 24,915 19,335 72,648 53,467 General and administrative 12,086 8,176 31,020 24,437

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based compensation			$ 168,601	$ 132,057
Cost of revenue
Share-based compensation	$ 5,343	$ 4,831	15,047	15,077
Research and development
Share-based compensation	17,189	13,921	49,886	39,076
Sales and marketing
Share-based compensation	24,915	19,335	72,648	53,467
General and administrative
Share-based compensation	$ 12,086	$ 8,176	$ 31,020	$ 24,437

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (54,417)	$ (40,703)	$ (161,789)	$ (148,142)
Other comprehensive (loss) income, before tax:
Net unrealized (loss) gain on available-for-sale investments	(863)	(1,361)	(3,664)	2,817
Net unrealized (loss) gain on derivative instruments	(2,354)	388	(7,972)	(848)
Other comprehensive (loss) income, before tax	(3,217)	(973)	(11,636)	1,969
Tax effect	0	699	0	0
Other comprehensive (loss) income, net of tax	(3,217)	(274)	(11,636)	1,969
Comprehensive loss	$ (57,634)	$ (40,977)	$ (173,425)	$ (146,173)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances at beginning of period (in shares) at Dec. 31, 2019		113,081
Balances at beginning of period at Dec. 31, 2019	$ 457,984	$ 1,130	$ 1,155,044	$ 591	$ (698,781)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		911
Issuance of common stock upon exercise of stock options	24,591	$ 9	24,582
Issuance of common stock for settlement of RSUs and PRSUs (in shares)		2,118
Issuance of common stock for settlement of RSUs and PRSUs	(6,129)	$ 21	(6,150)
Issuance of common stock in connection with employee stock purchase plan (in shares)		353
Issuance of common stock in connection with employee stock purchase plan	19,952	$ 4	19,948
Share-based compensation	135,326		135,326
Equity component of 2025 convertible senior notes	216,026		216,026
Adjustments to Additional Paid in Capital, Purchase Of Capped Call Transactions	(129,950)		(129,950)
Equity component of partial repurchase of 2023 convertible senior notes	(224,639)		(224,639)
Proceeds from capped calls related to 2023 convertible senior notes	83,040		83,040
Other comprehensive loss, net of tax	1,969			1,969
Net loss	(148,142)				(148,142)
Other	90		15		75
Balances at end of period (in shares) at Sep. 30, 2020		116,463
Balances at end of period at Sep. 30, 2020	430,119	$ 1,164	1,273,242	2,560	(846,848)
Balances at beginning of period (in shares) at Jun. 30, 2020		115,186
Balances at beginning of period at Jun. 30, 2020	410,310	$ 1,150	1,212,471	2,834	(806,145)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		577
Issuance of common stock upon exercise of stock options	15,489	$ 6	15,483
Issuance of common stock for settlement of RSUs and PRSUs (in shares)		700
Issuance of common stock for settlement of RSUs and PRSUs	(1,990)	$ 8	(1,998)
Share-based compensation	47,271		47,271
Other comprehensive loss, net of tax	(274)			(274)
Net loss	(40,703)				(40,703)
Other	15		15
Balances at end of period (in shares) at Sep. 30, 2020		116,463
Balances at end of period at Sep. 30, 2020	430,119	$ 1,164	1,273,242	2,560	(846,848)
Balances at beginning of period (in shares) at Dec. 31, 2020		117,489
Balances at beginning of period at Dec. 31, 2020	$ 431,831	$ 1,174	1,344,337	3,203	(916,883)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	820	820
Issuance of common stock upon exercise of stock options	$ 18,889	$ 8	18,881
Issuance of common stock for settlement of RSUs and PRSUs (in shares)		1,833
Issuance of common stock for settlement of RSUs and PRSUs	(8,940)	$ 18	(8,958)
Issuance of common stock in connection with employee stock purchase plan (in shares)		380
Issuance of common stock in connection with employee stock purchase plan	27,655	$ 4	27,651
Share-based compensation	171,935		171,935
Other comprehensive loss, net of tax	(11,636)			(11,636)
Net loss	(161,789)				(161,789)
Other	331			48	283
Balances at end of period (in shares) at Sep. 30, 2021		120,522
Balances at end of period at Sep. 30, 2021	468,276	$ 1,204	1,553,846	(8,385)	(1,078,389)
Balances at beginning of period (in shares) at Jun. 30, 2021		119,789
Balances at beginning of period at Jun. 30, 2021	464,127	$ 1,197	1,492,117	(5,216)	(1,023,971)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		212
Issuance of common stock upon exercise of stock options	3,754	$ 2	3,752
Issuance of common stock for settlement of RSUs and PRSUs (in shares)		521
Issuance of common stock for settlement of RSUs and PRSUs	(2,637)	$ 5	(2,642)
Share-based compensation	60,619		60,619
Other comprehensive loss, net of tax	(3,217)			(3,217)
Net loss	(54,417)				(54,417)
Other	47			48	(1)
Balances at end of period (in shares) at Sep. 30, 2021		120,522
Balances at end of period at Sep. 30, 2021	$ 468,276	$ 1,204	$ 1,553,846	$ (8,385)	$ (1,078,389)

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (161,789)	$ (148,142)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization	27,953	32,602
Share-based compensation	168,601	132,057
Amortization of deferred costs	48,739	32,390
Amortization of debt discount and issuance costs	38,085	26,230
Loss on early extinguishment of debt	0	25,950
Repayment of convertible senior notes attributable to debt discount	0	(38,637)
Allowance for credit losses on accounts receivable	6,199	8,450
Other, net	1,241	(2,315)
Changes in operating assets and liabilities:
Accounts receivable	3,733	(33,035)
Prepaid expenses and other current assets	(9,385)	(3,116)
Deferred costs	(75,846)	(47,292)
Lease right-of-use assets	12,876	15,472
Other assets and liabilities	(3,888)	(1,022)
Accounts payable	18,304	(26,208)
Accrued liabilities	1,349	1,569
Accrued compensation and related benefits	16,059	18,252
Deferred revenue	64,710	4,369
Lease liabilities	(22,658)	(17,503)
Net cash provided by (used in) operating activities	134,283	(19,929)
Cash flows from investing activities
Purchases of property and equipment	(11,030)	(19,489)
Internal-use software development costs	(10,837)	(10,901)
Purchases of marketable securities	(718,636)	(701,367)
Proceeds from maturities of marketable securities	590,588	281,476
Proceeds from sales of marketable securities	101,995	105,506
Business combinations, net of cash acquired	(7,811)	0
Purchases of strategic investments	(1,000)	(1,500)
Proceeds from sales of strategic investments	1,008	1,577
Net cash used in investing activities	(55,723)	(344,698)
Cash flows from financing activities
Proceeds from issuance of convertible senior notes, net of issuance costs paid of $21,010	0	1,128,990
Purchase of capped calls related to 2025 convertible senior notes	0	(129,950)
Payments for 2023 convertible senior notes partial repurchase	0	(578,973)
Proceeds from capped calls related to 2023 convertible senior notes	0	83,040
Proceeds from exercises of employee stock options	18,889	24,591
Proceeds from employee stock purchase plan	37,136	28,913
Taxes paid related to net share settlement of share-based awards	(8,940)	(6,127)
Net cash provided by financing activities	47,085	550,484
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(33)	237
Net increase in cash, cash equivalents and restricted cash	125,612	186,094
Cash, cash equivalents and restricted cash at beginning of period	407,859	199,905
Cash, cash equivalents and restricted cash at end of period	533,471	385,999
Reconciliation of cash, cash equivalents and restricted cash to condensed consolidated balance sheets
Cash and cash equivalents	532,517	383,318
Restricted cash included in prepaid expenses and other current assets	949	1,957
Restricted cash included in other assets	5	724
Total cash, cash equivalents and restricted cash	533,471	385,999
Supplemental cash flow data
Cash paid for interest	3,967	1,174
Cash paid for taxes	7,940	3,093
Non-cash investing and financing activities
Balance of property and equipment in accounts payable and accrued expenses	1,069	1,642
Property and equipment acquired through tenant improvement allowances	429	110
Internal-use software development costs
Non-cash investing and financing activities
Share-based compensation capitalized in internal-use software development costs and in deferred costs	1,317	2,536
Deferred costs
Non-cash investing and financing activities
Share-based compensation capitalized in internal-use software development costs and in deferred costs	$ 2,013	$ 1,229

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Statement of Cash Flows [Abstract]
Payments of debt issuance costs associated with convertible notes	$ 21,010

Overview and Basis of Presentat

Overview and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview and Basis of Presentation	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, solutions that are intended to help organizations and their customers build better experiences. Our customer experience solutions are 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. With our origins in customer service, we have evolved our offerings over time to product and platform solutions that work together to help organizations understand the broader customer journey, improve communications across all channels, and engage where and when it’s needed most. 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, 2020, filed with the SEC on February 12, 2021. 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. The consolidated balance sheet as of December 31, 2020 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 our financial position, results of operations, comprehensive loss, stockholders’ equity, 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, 2021. 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 estimate of variable consideration related to revenue recognition; • the estimate of credit losses for accounts receivable and marketable securities; • the fair value and useful lives of acquired intangible assets; • the capitalization and useful life of capitalized costs to obtain customer contracts; • the valuation of strategic investments; • the fair value and useful lives of property and equipment; • the capitalization and useful lives of internal-use software; • the lease term and incremental borrowing rate for lease liabilities; • the fair value of our convertible senior notes; • the fair value of asset retirement obligations; • the fair value and expense recognition for certain share-based awards; • the preparation of financial forecasts used in currency hedging; • the recognition and measurement of legal contingencies; and • the recognition of tax benefits and forecasts used to determine our effective tax rate. As of the date of issuance of the financial statements, we are not aware of any material specific events or circumstances that would require us to update our estimates, judgments, or to revise the carrying values of our assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to our financial statements. Concentrations of Risk As of September 30, 2021 and December 31, 2020, 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 and nine months ended September 30, 2021 or 2020. Recently Issued Accounting Pronouncements In August 2020, the Financial Accounting Standards Board, or FASB, issued ASU 2020-06, regarding ASC Topic 470 “Debt ” and ASC Topic 815 “ Derivatives and Hedging ,” which reduces the number of accounting models for convertible instruments, including amending the calculation of diluted earnings per share and the balance sheet presentation of those instruments, as well as the resulting recognition of interest expense, among other changes. The guidance is effective for annual reporting periods beginning after December 15, 2021, including interim periods within that reporting period. Early adoption is permitted. We are currently evaluating the impact of the adoption of this standard on our consolidated financial statements.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business Combinations Cleverly, Lda. In the third quarter of 2021, we completed the acquisition of Cleverly, Lda., or Cleverly, resulting in increases of $7 million and $1 million to goodwill and developed technology, respectively. From the date of the acquisition, the financial results of Cleverly have been included in and are immaterial to our condensed consolidated financial statements. Pro forma revenue and results of operations have not been presented because the historical results are not material to our condensed consolidated financial statements in any period presented. Pending Acquisition On October 28, 2021, we entered into a definitive agreement to acquire Momentive Global Inc., or Momentive, an experience management company that offers SaaS feedback solutions. Under the terms of the agreement, each issued and outstanding share of Momentive common stock will be converted into the right to receive 0.225 shares of Zendesk common stock. The agreement also provides for Zendesk’s assumption of outstanding options and other unvested equity awards held by continuing Momentive employees. The transaction, which is anticipated to close in the first half of calendar year 2022, is subject to approval by Zendesk and Momentive stockholders, the receipt of required regulatory approvals, and other customary closing conditions. A fee of up to $150 million may be payable by Zendesk or by Momentive upon termination of the transaction, as more fully described in the agreement.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Financial Instruments	Financial Instruments Investments The following tables present information about our financial assets measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands): Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 413,386 $ 413,386 U.S. Treasury securities — 401,614 401,614 Money market funds 279,370 — 279,370 Asset-backed securities — 104,765 104,765 Agency securities — 51,684 51,684 Commercial paper — 33,687 33,687 Certificates of deposit and time deposits — 7,345 7,345 Total $ 279,370 $ 1,012,481 $ 1,291,851 Included in cash and cash equivalents $ 279,370 Included in marketable securities $ 1,012,481 Fair Value Measurement at Level 1 Level 2 Total Description U.S. Treasury securities $ — $ 431,087 $ 431,087 Corporate bonds — 366,638 366,638 Money market funds 162,156 — 162,156 Asset-backed securities — 101,239 101,239 Agency securities — 80,394 80,394 Commercial paper — 36,954 36,954 Certificates of deposit and time deposits — 10,657 10,657 Total $ 162,156 $ 1,026,969 $ 1,189,125 Included in cash and cash equivalents $ 194,854 Included in marketable securities $ 994,271 As of September 30, 2021 and December 31, 2020, there were no securities within Level 3 of the fair value hierarchy. There were no transfers between fair value measurement levels during the three and nine months ended September 30, 2021 or 2020. As of September 30, 2021, gross unrealized gains and losses for marketable securities wer e $3 million and not material, respectively. The aggregate amortized cost basis for cash equivalents and marketable securities was $1,289 million and excludes accrued interest of $3 million. The aggregate fair value of securities with unrealized losses was $292 million. As of December 31, 2020, gross unrealized gains and losses for marketable securities were $6 million and not material, respectively. The aggregate amortized cost basis for cash equivalents and marketable securities was $1,183 million and excludes accrued interest of $3 million. The aggregate fair value of securities with unrealized losses was $107 million. Unrealized losses for securities that have been in an unrealized loss position for more than 12 months as of September 30, 2021 and December 31, 2020 were not material. We have not recorded an allowance for credit losses, as we believe any such losses would be immaterial based on the high-grade credit rating for each of our marketable securities as of the end of each period. We intend to hold our marketable securities to maturity and it is unlikely that they would be sold before their cost bases are recovered. The following table classifies our marketable securities by contractual maturity (in thousands): September 30, December 31, Due in one year or less $ 421,328 $ 565,593 Due after one year and within five years 591,153 428,678 Total $ 1,012,481 $ 994,271 As of September 30, 2021 and December 31, 2020, the balance of strategic investments without readily determinable fair values was $12 million and $11 million, respectively. There have been no adjustments to the carrying values of strategic investments resulting from impairments or observable price changes. During the three months ended September 30, 2021, we sold a strategic investment and realized a gain of approximately $1 million, which was recorded in interest and other income (expense), net in our consolidated statements of operations. For our other financial instruments, including accounts receivable, accounts payable, and other current liabilities, the carrying amounts approximate their fair values 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 of our products. 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. We include time value related to our cash flow hedges for effectiveness testing purposes and the entire change in the unrecognized value of our hedge contracts is recorded in accumulated other comprehensive income (loss), or AOCI. As of September 30, 2021, the balance of AOCI include d an unrecognized net loss of $6 million related to the changes in the fair value of foreign currency forward contracts designated as cash flow hedges. We expect to reclassify a net loss of $7 million 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 (in thousands): September 30, 2021 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value Balance Sheet Location Fair Value Foreign currency forward contracts Other current assets $ 5,268 Accrued liabilities $ 9,874 Total $ 5,268 $ 9,874 December 31, 2020 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value Balance Sheet Location Fair Value Foreign currency forward contracts Other current assets $ 7,922 Accrued liabilities $ 5,768 Total $ 7,922 $ 5,768 Our foreign currency forward contracts had a total notional value of $452 million and $345 million as of September 30, 2021 and December 31, 2020, respectively. We have a master netting arrangement with each of our counterparties, which permit net settlement of multiple, separate derivative contracts with a single payment. We do not have collateral requirements with any of our counterparties. GAAP 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. We do not enter into any derivative contracts for trading or speculative purposes. All derivatives have been designated as hedging instruments. The following table presents information about our foreign currency forward contracts on our consolidated statements of operations for the three and nine months ended September 30, 2021 and 2020 (in thousands): Gain (Loss) Reclassified from AOCI into Earnings Three Months Ended September 30, Nine Months Ended September 30, Classification 2021 2020 2021 2020 Revenue $ (1,126) $ 100 $ (3,207) $ 1,222 Cost of revenue (76) 163 814 (701) Research and development (92) 174 911 (671) Sales and marketing (180) 366 1,893 (1,350) General and administrative (53) 108 654 (374) Total $ (1,527) $ 911 $ 1,065 $ (1,874) Th e loss r ecognized in AOCI related to foreign currency forward contracts was $4 million for the three months ended September 30, 2021. The gain recognized in AOCI related to foreign currency forward contracts was $1 million for the three months ended September 30, 2020. The loss recognized in AOCI related to foreign currency forward contracts was $7 million and $3 million for the nine months ended September 30, 2021 and 2020, respectively. The cash flow effects related to foreign currency forward contracts are included within operating activities on our consolidated statements of cash flows. Convertible Senior Notes As of September 30, 2021, the fair values of our 0.25% convertible senior notes due 2023 and our 0.625% convertible senior notes due 2025 were $283 million and $1,440 million, respectively. We estimate the fair value of our convertible senior notes based on their last traded prices or market observable inputs, resulting in a Level 2 classification in the fair value hierarchy. Based on the closing price of our common stock of $116.39 on the last trading day of the quarter, the if-converted values of the 2023 and 2025 convertible senior notes exceeded their remaining principal amounts by $126 million and $81 million, respectively, as of September 30, 2021.

Costs to Obtain Customer Contra

Costs to Obtain Customer Contracts	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Costs to Obtain Customer Contracts	Costs to Obtain Customer ContractsThe balance of deferred costs to obtain customer contracts was $134 million and $105 million as of September 30, 2021 and December 31, 2020, respectively. Amortization expense for deferred costs was $18 million and $12 million for the three months ended September 30, 2021 and 2020, respectively, and $49 million and $32 million for the nine months ended September 30, 2021 and 2020, respectively. There were no impairment losses related to deferred costs for the periods presented.Deferred Revenue and Performance Obligations The changes in the balances of deferred revenue are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Balance, beginning of period $ 442,463 $ 316,113 $ 383,358 $ 323,962 Billings 352,580 273,464 1,027,949 749,755 Subscription and services revenue (327,812) (249,052) (912,665) (707,715) Other revenue* (19,162) (12,874) (50,573) (38,351) Balance, end of period $ 448,069 $ 327,651 $ 448,069 $ 327,651 *Other revenue primarily includes implementation and training services, Talk usage, and amounts from contract assets. For the three months ended September 30, 2021 and 2020, the majority of revenue recognized was from the deferred revenue balances at the beginning of each period. For the nine months ended September 30, 2021 and 2020, less than half of revenue recognized was from the deferred revenue balances at the beginning of each period. The aggregate balance of remaining performance obligations as of September 30, 2021 was $1,167 million. We expect to recognize $783 million of the balance as revenue in the next 12 months and the substantial majority of the remainder in the next 13-36 months. The aggregate balance of remaining performance obligations represents contracted revenue that has not yet been recognized, including contracted revenue from renewals, and does not include contract amounts which are cancellable by the customer and amounts associated with optional renewal periods.

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment, net consists of the following (in thousands): September 30, December 31, Leasehold improvements $ 79,702 $ 91,205 Capitalized internal-use software 57,849 48,730 Computer equipment and licensed software and patents 37,871 30,725 Furniture and fixtures 14,644 13,759 Construction in progress 17,481 13,222 Total 207,547 197,641 Less: accumulated depreciation and amortization (114,024) (103,433) Property and equipment, net $ 93,523 $ 94,208 Depreciation expense was $6 million and $7 million for the three months ended September 30, 2021 and 2020, respectively, and $17 million and $20 million for the nine months ended September 30, 2021 and 2020, respectively.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	Leases The following table presents information about leases on our consolidated balance sheets (in thousands): September 30, 2021 December 31, 2020 Assets Lease right-of-use assets $ 73,094 $ 84,013 Liabilities Lease liabilities 20,201 23,533 Lease liabilities, noncurrent 66,733 85,275 As of September 30, 2021, the weighted average remaining lease term was 5.8 years and the weighted average discount rate was 4.6%. The following table presents information about leases on our consolidated statements of operations (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating lease expense $ 5,455 $ 6,573 $ 16,583 $ 19,590 Short-term lease expense 130 128 386 451 Variable lease expense 1,297 1,412 3,759 4,614 Sublease income (450) (422) (1,324) (1,281) The following table presents supplemental cash flow information about our leases (in thousands): Nine Months Ended September 30, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 20,460 $ 24,029 Operating lease assets obtained in exchange for new lease liabilities 4,452 14,960 In the fourth quarter of 2020, we determined that we would no longer occupy the leased premises located at 1019 Market Street and 988 Market Street, San Francisco, California 94103 and recorded an aggregate impairment charge of $15 million related to lease right-of-use assets and leasehold improvements. In the second quarter of 2021, we executed a termination agreement for the leased premises located at 1019 Market Street, including a one-time payment of $7 million, which is not included in the supplemental cash flow table above.

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Acquired Intangible Assets	Goodwill and Acquired Intangible Assets The changes in the carrying amount of goodwill for the nine months ended September 30, 2021 are as follows (in thousands): Balance as of December 31, 2020 $ 169,662 Goodwill acquired 7,103 Balance as of September 30, 2021 $ 176,765 Acquired intangible assets subject to amortization consist of the following (in thousands): As of September 30, 2021 Cost Accumulated Net Weighted Average Remaining Useful Life (In years) Developed technology $ 28,000 $ (12,528) $ 15,472 3.3 Customer relationships 14,300 (7,591) 6,709 3.4 $ 42,300 $ (20,119) $ 22,181 As of December 31, 2020 Cost Accumulated Net Weighted Average Remaining Useful Life (In years) Developed technology $ 30,200 $ (12,445) $ 17,755 4.1 Customer relationships 14,710 (6,076) 8,634 4.0 Backlog 3,200 (3,033) 167 0.3 $ 48,110 $ (21,554) $ 26,556 In the third quarter of 2021, we removed developed technology, customer relationships, and backlog intangible assets which had become fully amortized from our consolidated balance sheet. Amortization expense of acquired intangible assets was $2 million for each of the three months ended September 30, 2021 and 2020, and $5 million and $7 million for the nine months ended September 30, 2021 and 2020, respectively. Estimated future amortization expense as of September 30, 2021 is as follows (in thousands): Remainder of 2021 $ 1,861 2022 7,279 2023 6,583 2024 4,839 2025 972 Thereafter 647 $ 22,181

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior Notes 2025 Convertible Senior Notes In June 2020, we issued $1,150 million aggregate principal amount of 0.625% convertible senior notes due June 15, 2025 in a private offerin g , the “2025 Notes.” The 2025 Notes are senior unsecured obligations and bear interest at a fixed rate of 0.625% per annum, payable semi-annually in arrears on June 15 and December 15 of each year, commencing on D ecember 15, 2020. The total net pr oceeds from the offering, after deducting initial purchase discounts and estimated debt issuance costs, were approxim ately $1,129 million. Each $1,000 principal amount of the 2025 Notes will initially be convertible into 9.1944 shares of our common stock, which is equivalent to an initial conversion price of approximately $108.76 per share, subject to adjustment upon the occurrence of specified events. The 2025 Notes will be convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding March 15, 2025, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on September 30, 2020 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five On or after March 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their 2025 Notes, in minimum denominations of $1,000 or an integral multiple in excess thereof, at the option of the holders regardless of the foregoing circumstances. Upon conversion, we will pay or deliver, as the case may be, cash, shares of our common stock or a combination of cash and shares of our common stock, at our election. If certain specified fundamental changes occur (as set forth in the indenture) prior to the maturity date, holders of the 2025 Notes may require us to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the 2025 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if specific corporate events occur prior to the applicable maturity date or if we deliver a notice of redemption, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event or converts its notes called (or deemed called) for redemption in connection with such notice of redemption in certain circumstances. It is our current intent and policy to settle conversions through combination settlement with a specified dollar amount of $1,000 per $1,000 principal amount of 2025 Notes. During the three months ended September 30, 2021, the conditions allowing holders of the 2025 Notes to convert were not met. As the criteria for conversion were not met, the 2025 Notes are classified as a long-term liability as of September 30, 2021. We may not redeem the 2025 Notes prior to June 20, 2023. We may redeem for cash all or any portion of the 2025 Notes, at our option, on or after June 20, 2023 and on or prior to the 41st scheduled trading day immediately preceding the maturity date, if the last reported sale price of our common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which we provide notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which we provide notice of redemption, at a redemption price equal to 100% of the principal amount of the 2025 Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the 2025 Notes. In accounting for the transaction, the 2025 Notes were separated into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The fair value of the liability component was estimated by calculating the present value of expected cash flows using an interest rate that reflects our incremental borrowing rate, with an estimated adjustment for our credit standing on nonconvertible debt with similar maturity. The carrying amount of the equity component representing the conversion option was $220 million and was determined by deducting the fair value of the liability component from the par value of the 2025 Notes. The equity component was recorded in additional paid-in capital and is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the contractual term of the 2025 Notes at an effective interest rate of 5.00%. In accounting for the debt issuance costs of $21 million related to the 2025 Notes, we allocated the total amount incurred to the liability and equity components of the 2025 Notes based on their relative values. Issuance costs attributable to the liability component were $17 million and will be amortized to interest expense using the effective interest method over the contractual term of the 2025 Notes. Issuance costs attributable to the equity component were netted with the equity component in additional paid-in capital. The net carrying amount of the liability component of the 2025 Notes is as follows (in thousands): September 30, December 31, Principal $ 1,150,000 $ 1,150,000 Unamortized Debt Discount (168,392) (198,857) Unamortized issuance costs (13,420) (15,567) Net carrying amount $ 968,188 $ 935,576 The net carrying amount of the equity component of the 2025 Notes is as follows (in thousands): September 30, December 31, Debt Discount for Conversion Option $ 220,061 $ 220,061 Issuance costs (4,035) (4,035) Net carrying amount $ 216,026 $ 216,026 The interest expense related to the 2025 Notes is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Contractual interest expense $ 1,797 $ 1,797 $ 5,391 $ 2,076 Amortization of Debt Discount 10,281 9,785 30,465 11,297 Amortization of issuance costs 735 660 2,147 761 Total interest expense $ 12,813 $ 12,242 $ 38,003 $ 14,134 The difference between the book and tax treatment of the debt discount and debt issuance costs of the 2025 Notes resulted in a difference between the carrying amount and tax basis of the 2025 Notes. This taxable temporary difference resulted in the recognition of a $51 million net deferred tax liability which was recorded as an adjustment to additional paid-in capital. The creation of the deferred tax liability represents a source of future taxable income which supports realization of deferred tax assets. As we continue to maintain a full valuation allowance against its deferred tax assets, this additional source of income resulted in the release of a portion of its valuation allowance. Consistent with the adoption of ASU 2019-12, the release of the valuation allowance of $51 million was recorded as an adjustment to additional paid-in capital. 2025 Capped Calls In connection with the pricing of the 2025 Notes, we entered into privately negotiated capped call transactions with certain counterparties, the “2025 Capped Calls.” The 2025 Capped Calls each have an initial strike price of approximately $108.76 per share, subject to certain adjustments, which correspond to the initial conversion price of the 2025 Notes. The 2025 Capped Calls have initial cap prices of $164.17 per share, subject to certain adjustments. The 2025 Capped Calls cover, subject to anti-dilution adjustments, approximately 10.6 million shares of our common stock. Conditions that cause adjustments to the initial strike price of the 2025 Capped Calls are similar to the conditions that result in corresponding adjustments for the 2025 Notes. The 2025 Capped Calls are generally intended to reduce or offset the potential dilution to our common stock upon any conversion of the 2025 Notes with such reduction or offset, as the case may be, subject to a cap based on the cap price. For accounting purposes, the 2025 Capped Calls are separate transactions, and not part of the terms of the 2025 Notes. As these transactions meet certain accounting criteria, the 2025 Capped Calls are recorded in stockholders’ equity and are not accounted for as derivatives. The cost of $130 million incurred in connection with the 2025 Capped Calls was recorded as a reduction to additional paid-in capital. 2023 Convertible Senior Notes In March 2018, we issued $575 million aggregate principal amount of 0.25% convertible senior notes due March 15, 2023 in a private offering, the “2023 Notes.” The 2023 Notes are unsecured obligations and bear interest at a fixed rate of 0.25% per annum, payable semi-annually in arrears on March 15 and September 15 of each year, commencing on September 15, 2018. The total net proceeds from the offering, after deducting initial purchase discounts and estimated debt issuance costs, were approximately $561 million. In connection with the offering of the 2025 Notes, we used $618 million of the net proceeds from the offering of the 2025 Notes to repurchase $426 million aggregate principal amount of the 2023 Notes in cash through individual privately negotiated transactions, the “2023 Notes Partial Repurchase.” Of the $618 million consideration, $393 million and $225 million were allocated to the debt and equity components on our consolidated balance sheets, respectively, utilizing an effective interest rate to determine the fair value of the liability component. The fair value of the liability component is estimated by calculating the present value of expected cash flows using an interest rate that reflects our incremental borrowing rate, with an estimated adjustment for our credit standing on nonconvertible debt with similar maturity. As of the repurchase date, the carrying value of the 2023 Notes subject to the 2023 Notes Partial Repurchase, net of unamortized debt discount and issuance costs, was $367 million. The 2023 Notes Partial Repurchase resulted in a $26 million loss on early debt extinguishment. Additionally, $39 million of the total consideration was related to repayment of the debt discount and reflected as a cash outflow from operating activities. As of September 30, 2021, $149 million of principal remains outstanding on the 2023 Notes. Each $1,000 principal amount of the 2023 Notes will initially be convertible into 15.8554 shares of our common stock, the “Conversion Option,” which is equivalent to an initial conversion price of approximately $63.07 per share, subject to adjustment upon the occurrence of specified events. The 2023 Notes will be convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding December 15, 2022, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2018 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five In addition, if specific corporate events occur prior to the applicable maturity date, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances. It is our current intent and policy to settle conversions through combination settlement with a specified dollar amount of $1,000 per $1,000 principal amount of 2023 Notes. During the three months ended September 30, 2021, the conditions allowing holders of the 2023 Notes to convert were met. The 2023 Notes are therefore convertible during the three months ending December 31, 2021, and are classified as a current liability as of September 30, 2021. To date, we have received one request for conversion for an immaterial amount of 2023 Notes. In accounting for the issuance of the 2023 Notes, the 2023 Notes were separated into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated conversion feature. The carrying amount of the equity component was determined by deducting the fair value of the liability component from the par value of the 2023 Notes. The equity component was recorded in additional paid-in capital and is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the contractual term of the 2023 Notes at an effective interest rate of 5.26%. In accounting for the debt issuance costs related to the 2023 Not es, we allocated the total amount incurred to the liability and equity components of the 2023 Notes based on their relative values. Issuance costs attributable to the liability component are amortized to interest expense using the effective interest method over the contractual term of the 2023 Notes. Issuance costs attributable to the equity component were netted with the equity component in additional paid-in capital. The net carrying amount of the liability component of the 2023 Notes is as follows (in thousands): September 30, December 31, Principal $ 149,194 $ 149,194 Unamortized Debt Discount (10,362) (15,394) Unamortized issuance costs (971) (1,412) Net carrying amount $ 137,861 $ 132,388 The net carrying amount of the equity component of the 2023 Notes is as follows (in thousands): September 30, December 31, Debt Discount for Conversion Option $ 32,427 $ 32,427 Issuance costs (765) (765) Net carrying amount $ 31,662 $ 31,662 The interest expense related to the 2023 Notes is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Contractual interest expense $ 93 $ 93 $ 279 $ 770 Amortization of Debt Discount 1,699 1,614 5,032 13,097 Amortization of issuance costs 151 135 441 1,075 Total interest expense $ 1,943 $ 1,842 $ 5,752 $ 14,942 2023 Capped Calls In connection with the pricing of the 2023 Notes, we entered into privately negotiated capped call transactions with certain counterparties, the “2023 Capped Calls.” The 2023 Capped Calls each have an initial strike price of approximately $63.07 per share, subject to certain adjustments, which correspond to the initial conversion price of the 2023 Notes. The 2023 Capped Calls have initial cap prices of $95.20 per share, subject to certain adjustments. The 2023 Capped Calls covered, subject to anti-dilution adjustments, approximately 9.1 million shares of our common stock. Conditions that cause adjustments to the initial strike price of the 2023 Capped Calls mirror conditions that result in corresponding adjustments for the 2023 Notes. The 2023 Capped Calls are generally intended to reduce or offset the potential dilution to our common stock upon any conversion of the 2023 Notes with such reduction or offset, as the case may be, subject to a cap based on the cap price. For accounting purposes, the 2023 Capped Calls are separate transactions, and not part of the terms of the 2023 Notes. As these transactions meet certain accounting criteria, the 2023 Capped Calls are recorded in stockholders’ equity and are not accounted for as derivatives. The cost of $64 million incurred in connection with the 2023 Capped Calls was recorded as a reduction to additional paid-in capital. In June 2020, and in connection with the 2023 Notes Partial Repurchase, we terminated the 2023 Capped Calls corresponding to approximately 6.7 million shares for cash proceeds of $83 million. The proceeds were recorded as an increase to additional paid-in capital in the consolidated balance sheets. As of September 30, 2021, there remains outstanding 2023 Capped Calls giving the Company the option to purchase approximately 2.4 million shares (subject to adjustment). The net impact to our stockholders ’ equity, included in additional paid-in capital, of the above components of the 2023 Notes is as follows (in thousands): At Issuance Conversion Option $ 124,976 Purchase of Capped Calls (63,940) Issuance Costs (2,948) Net deferred tax liability (13,784) Total $ 44,304

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Except as discussed below, there were no material changes in our commitments under contractual obligations as disclosed in our audited consolidated financial statements for the year ended December 31, 2020. In April 2021, we renewed an agreement with a cloud services provider for which we have a total obligation of $64 million over a three-year period. Litigation and Loss Contingencies We accrue estimates for resolution of legal and other contingencies when losses are probable and estimable. These estimates are reviewed at least quarterly 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. On October 24, 2019 and November 7, 2019, purported stockholders of the Company filed two putative class action complaints in the United States District Court for the Northern District of California, entitled Charles Reidinger v. Zendesk, Inc., et al., 3:19-cv-06968-CRB and Ho v. Zendesk, Inc., et al., No. 3:19-cv-07361-WHA, respectively, against the Company and certain of the Company’s executive officers. The complaints are nearly identical and allege violations of Section 10(b) and Section 20(a) of the Securities Exchange Act of 1934, as amended, purportedly on behalf of all persons who purchased Zendesk, Inc. common stock between February 6, 2019 and October 1, 2019, inclusive. The claims are based upon allegations that the defendants misrepresented and/or omitted material information in certain of our prior public filings. To this point, no discovery has occurred in these cases. The court appointed a lead plaintiff and consolidated the various lawsuits into a single action (Case No. 3:19-cv-06968-CRB), and the lead plaintiff filed its amended complaint on April 14, 2020 asserting the same alleged violations of securities laws as the initial complaints. On June 29, 2020, Zendesk and the executive officer defendants moved to dismiss the amended complaint. On November 9, 2020, the court granted Zendesk's motion to dismiss and granted plaintiff leave to amend its complaint. On January 8, 2021, plaintiff filed its second amended complaint and on January 22, 2021, Zendesk and the executive officer defendants moved to dismiss the second amended complaint. On March 2, 2021, the court granted Zendesk's motion to dismiss the second amended complaint. On March 23, 2021, judgment was entered in favor of Zendesk and the executive officer defendants. On April 20, 2021, plaintiff filed a notice of appeal with the U.S. Court of Appeals for the Ninth Circuit. On July 29, 2021, plaintiff filed its opening brief in the appeal, and on October 13, 2021, the Company and the executive officer defendants filed their answering brief. On June 2, 2020, a purported stockholder of the Company filed a derivative complaint in the United States District Court for the Northern District of California, entitled Anderson v. Svane, et al., 3:20-cv-03671, against certain of the Company’s executive officers and directors. The derivative complaint alleges breaches of fiduciary duty against all defendants, and an insider trading claim and violations of Section 10(b) of the Securities Exchange Act of 1934 against the officer defendants, purportedly on behalf of the Company itself. The claims are based on nearly identical allegations as the two putative class action complaints described above, namely that the defendants misrepresented and/or omitted material information in certain of our prior public filings. On July 27, 2020, the court ordered the derivative action related to the class action. The derivative action had been stayed pending resolution of the class action. On May 6, 2021, the court approved a joint stipulation to extend the stay of action pending the outcome of the appeal of the class action. It is not possible for the Company to quantify the extent of potential liability to the individual defendants, if any. Management believes that the lawsuits lack merit and intends to vigorously defend the actions. We cannot predict the outcome of or estimate the possible loss or range of loss from the above described matter. From time to time, we may be subject to other legal proceedings, claims, investigations, and government inquiries in the ordinary course of business. We have received, and may in the future continue to receive, claims from third parties asserting, among other things, infringement of their intellectual property rights, defamation, labor and employment rights, privacy, and contractual rights. In general, the resolution of a legal matter could prevent the Company from offering its service to others, could be material to the Company’s financial condition or cash flows, or both, or could otherwise adversely affect the Company’s operating results. The outcomes of legal proceedings and other contingencies are inherently unpredictable and subject to significant uncertainties. As a result, the Company is not able to reasonably estimate the amount or range of possible losses in excess of any amounts accrued, including losses that could arise as a result of application of non-monetary remedies, with respect to the contingencies it faces. In management’s opinion, resolution of all current matters is not expected to have a material adverse impact on 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 consolidated financial statements as a result of these service-level agreements.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Common Stock and Stockholders' Equity	Common Stock and Stockholders’ Equity Common Stock As of September 30, 2021 and December 31, 2020, there were 400 million shares of common stock authorized for issuance with a par value of $0.01 per share, and 120.5 million and 117.5 million shares were issued and outstanding as of September 30, 2021 and December 31, 2020, respectively. Preferred Stock As of September 30, 2021 and December 31, 2020, there were 10 million shares of preferred stock 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 the 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 the offering period or the fair market value of our common stock at the end of the purchase period. In both May 2021 and 2020, 0.4 million shares of common stock were purchased under the ESPP. Pursuant to the terms of the ESPP, the number of shares reserved under the ESPP increased by 1.2 million shares on January 1, 2021. As of September 30, 2021, 5.6 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 initial public offering 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 5.9 million shares on January 1, 2021. As of September 30, 2021, we had 18.9 million shares of common stock available for future grants under the 2014 Plan. A summary of restricted stock unit (“RSU”) activity for the nine months ended September 30, 2021 is as follows (in thousands, except per share information): Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Unvested — January 1, 2021 5,141 $ 75.93 Granted 1,835 147.67 Vested (1,796) 68.49 Forfeited or canceled (742) 86.86 Unvested — September 30, 2021 4,438 $ 106.77 The total fair value of RSUs vested during the nine months ended September 30, 2021 and 2020 was $249 million and $168 million, respectively. The fair value of RSUs vested represents market value on the vesting date. A summary of stock option activity for the nine months ended September 30, 2021 is as follows (in thousands, except per share information): Stock Options Number of Weighted Weighted Aggregate (In years) Outstanding — January 1, 2021 4,235 $ 31.42 5.2 $ 473,358 Granted 411 148.05 Exercised (820) 23.02 Forfeited or canceled (118) 97.88 Outstanding — September 30, 2021 3,708 $ 44.09 5.0 $ 280,266 The aggregate intrinsic value for options outstanding represents the difference between the closing market price of our common stock on the last trading day of the reporting period and the exercise price of outstanding, in-the-money options. The total intrinsic value of stock options exercised during the nine months ended September 30, 2021 and 2020 was $94 million and $54 million, respectively. The intrinsic value for options exercised represents the difference between the exercise price and the market value on the date of exercise. The weighted-average grant date fair value of stock options granted during the nine months ended September 30, 2021 and 2020 was $52.60 and $31.41, respectively. As of September 30, 2021, we had a total of $477 million in future expense related to all equity awards to be recognized over a weighted average period of 2.7 years. For the three and nine months ended September 30, 2021, we recorded $2 million of share-based compensation expense related to accelerated vesting of share-based awards associated with certain employee terminations. Performance Restricted Stock Units In 2018, performance-based restricted stock units, or PRSUs, representing 0.2 million shares of common stock were granted in connection with the acquisition of FutureSimple Inc. The PRSUs vested in four semi-annual tranches through March 2021 and were subject to service and performance conditions. No expense was recorded in the three months ended September 30, 2021. F or the nine months ended September 30, 2021, we recorded $1 million of share-based compensation expense related to the P RSUs. F or the three and nine months ended September 30, 2020, we recorded $3 million and $5 million of share-based compensation expense related to the PRSUs, respectively. For the three and nine months ended September 30, 2021, zero and 37 thousand PRSUs were vested, respectively. For

Deferred Revenue and Performanc

Deferred Revenue and Performance Obligations	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Deferred Revenue and Performance Obligations	Costs to Obtain Customer ContractsThe balance of deferred costs to obtain customer contracts was $134 million and $105 million as of September 30, 2021 and December 31, 2020, respectively. Amortization expense for deferred costs was $18 million and $12 million for the three months ended September 30, 2021 and 2020, respectively, and $49 million and $32 million for the nine months ended September 30, 2021 and 2020, respectively. There were no impairment losses related to deferred costs for the periods presented.Deferred Revenue and Performance Obligations The changes in the balances of deferred revenue are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Balance, beginning of period $ 442,463 $ 316,113 $ 383,358 $ 323,962 Billings 352,580 273,464 1,027,949 749,755 Subscription and services revenue (327,812) (249,052) (912,665) (707,715) Other revenue* (19,162) (12,874) (50,573) (38,351) Balance, end of period $ 448,069 $ 327,651 $ 448,069 $ 327,651 *Other revenue primarily includes implementation and training services, Talk usage, and amounts from contract assets. For the three months ended September 30, 2021 and 2020, the majority of revenue recognized was from the deferred revenue balances at the beginning of each period. For the nine months ended September 30, 2021 and 2020, less than half of revenue recognized was from the deferred revenue balances at the beginning of each period. The aggregate balance of remaining performance obligations as of September 30, 2021 was $1,167 million. We expect to recognize $783 million of the balance as revenue in the next 12 months and the substantial majority of the remainder in the next 13-36 months. The aggregate balance of remaining performance obligations represents contracted revenue that has not yet been recognized, including contracted revenue from renewals, and does not include contract amounts which are cancellable by the customer and amounts associated with optional renewal periods.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	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 those related to outstanding share-based awards and our convertible senior notes, 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 Nine Months Ended 2021 2020 2021 2020 Net loss $ (54,417) $ (40,703) $ (161,789) $ (148,142) Weighted-average shares used to compute basic and diluted net loss per share 120,164 115,809 119,050 114,653 Net loss per share, basic and diluted $ (0.45) $ (0.35) $ (1.36) $ (1.29) The anti-dilutive securities excluded from the shares used to calculate diluted net loss per share are as follows (in thousands): As of September 30, 2021 2020 Shares subject to outstanding common stock options and employee stock purchase plan 3,894 4,607 Restricted stock units 4,438 5,171 Shares related to convertible senior notes 2,883 770 11,215 10,548 The shares related to convertible senior notes in the table above are calculated based on the average market price of our common stock for the three months ended September 30, 2021 and 2020, respectively. We expect to settle the principal amount of both the 2023 Notes and 2025 Notes in cash and therefore use the treasury stock method for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. The conversion spread has a dilutive impact on diluted net income per share when the average market price of our common stock for a given reporting period exceeds the initial conversion prices of $63.07 and $108.76

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We reported income tax expense of $3 million and $2 million for the three months ended September 30, 2021 and 2020 , respectively. We reported income tax expense of $8 million and $5 million for the nine months ended September 30, 2021 and 2020 , respectively. The effective tax rate for each period differs 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	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Geographic Information	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 Nine Months Ended 2021 2020 2021 2020 United States $ 174,264 $ 136,491 $ 489,476 $ 391,025 EMEA 102,889 73,798 282,323 210,487 APAC 35,730 28,954 98,700 81,105 Other 34,091 22,683 92,739 63,449 Total $ 346,974 $ 261,926 $ 963,238 $ 746,066 Long-Lived Assets The following table presents our long-lived assets by geographic area (in thousands): As of As of United States $ 61,317 $ 76,383 EMEA: Republic of Ireland 35,123 38,010 Other EMEA 6,837 5,784 Total EMEA 41,960 43,794 APAC: Singapore 14,786 19,560 Other APAC 6,643 6,466 Total APAC 21,429 26,026 Other 3,361 344 Total $ 128,067 $ 146,547

Overview and Basis of Present_2

Overview and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
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, 2020, filed with the SEC on February 12, 2021. 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. The consolidated balance sheet as of December 31, 2020 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 our financial position, results of operations, comprehensive loss, stockholders’ equity, 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, 2021.
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 estimate of variable consideration related to revenue recognition; • the estimate of credit losses for accounts receivable and marketable securities; • the fair value and useful lives of acquired intangible assets; • the capitalization and useful life of capitalized costs to obtain customer contracts; • the valuation of strategic investments; • the fair value and useful lives of property and equipment; • the capitalization and useful lives of internal-use software; • the lease term and incremental borrowing rate for lease liabilities; • the fair value of our convertible senior notes; • the fair value of asset retirement obligations; • the fair value and expense recognition for certain share-based awards; • the preparation of financial forecasts used in currency hedging; • the recognition and measurement of legal contingencies; and • the recognition of tax benefits and forecasts used to determine our effective tax rate. As of the date of issuance of the financial statements, we are not aware of any material specific events or circumstances that would require us to update our estimates, judgments, or to revise the carrying values of our assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to our financial statements.
Concentrations of Risk	As of September 30, 2021 and December 31, 2020, 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 and nine months ended September 30, 2021 or 2020.
Recently Issued Accounting Pronouncements	In August 2020, the Financial Accounting Standards Board, or FASB, issued ASU 2020-06, regarding ASC Topic 470 “Debt ” and ASC Topic 815 “ Derivatives and Hedging ,” which reduces the number of accounting models for convertible instruments, including amending the calculation of diluted earnings per share and the balance sheet presentation of those instruments, as well as the resulting recognition of interest expense, among other changes. The guidance is effective for annual reporting periods beginning after December 15, 2021, including interim periods within that reporting period. Early adoption is permitted. We are currently evaluating the impact of the adoption of this standard on our consolidated financial statements.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of 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 based on the three-tier fair value hierarchy (in thousands): Fair Value Measurement at Level 1 Level 2 Total Description Corporate bonds $ — $ 413,386 $ 413,386 U.S. Treasury securities — 401,614 401,614 Money market funds 279,370 — 279,370 Asset-backed securities — 104,765 104,765 Agency securities — 51,684 51,684 Commercial paper — 33,687 33,687 Certificates of deposit and time deposits — 7,345 7,345 Total $ 279,370 $ 1,012,481 $ 1,291,851 Included in cash and cash equivalents $ 279,370 Included in marketable securities $ 1,012,481 Fair Value Measurement at Level 1 Level 2 Total Description U.S. Treasury securities $ — $ 431,087 $ 431,087 Corporate bonds — 366,638 366,638 Money market funds 162,156 — 162,156 Asset-backed securities — 101,239 101,239 Agency securities — 80,394 80,394 Commercial paper — 36,954 36,954 Certificates of deposit and time deposits — 10,657 10,657 Total $ 162,156 $ 1,026,969 $ 1,189,125 Included in cash and cash equivalents $ 194,854 Included in marketable securities $ 994,271
Schedule of Marketable Securities Classified by Contractual Maturity	The following table classifies our marketable securities by contractual maturity (in thousands): September 30, December 31, Due in one year or less $ 421,328 $ 565,593 Due after one year and within five years 591,153 428,678 Total $ 1,012,481 $ 994,271
Schedule of Derivative Instruments on Consolidated Balance Sheets	The following tables present information about our derivative instruments on our consolidated balance sheets (in thousands): September 30, 2021 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value Balance Sheet Location Fair Value Foreign currency forward contracts Other current assets $ 5,268 Accrued liabilities $ 9,874 Total $ 5,268 $ 9,874 December 31, 2020 Asset Derivatives Liability Derivatives Derivative Instrument Balance Sheet Location Fair Value Balance Sheet Location Fair Value Foreign currency forward contracts Other current assets $ 7,922 Accrued liabilities $ 5,768 Total $ 7,922 $ 5,768
Schedule of Derivative Instruments on Statement of Operations	The following table presents information about our foreign currency forward contracts on our consolidated statements of operations for the three and nine months ended September 30, 2021 and 2020 (in thousands): Gain (Loss) Reclassified from AOCI into Earnings Three Months Ended September 30, Nine Months Ended September 30, Classification 2021 2020 2021 2020 Revenue $ (1,126) $ 100 $ (3,207) $ 1,222 Cost of revenue (76) 163 814 (701) Research and development (92) 174 911 (671) Sales and marketing (180) 366 1,893 (1,350) General and administrative (53) 108 654 (374) Total $ (1,527) $ 911 $ 1,065 $ (1,874)

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): September 30, December 31, Leasehold improvements $ 79,702 $ 91,205 Capitalized internal-use software 57,849 48,730 Computer equipment and licensed software and patents 37,871 30,725 Furniture and fixtures 14,644 13,759 Construction in progress 17,481 13,222 Total 207,547 197,641 Less: accumulated depreciation and amortization (114,024) (103,433) Property and equipment, net $ 93,523 $ 94,208

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Schedule of Lease Impact on Balance Sheet	The following table presents information about leases on our consolidated balance sheets (in thousands): September 30, 2021 December 31, 2020 Assets Lease right-of-use assets $ 73,094 $ 84,013 Liabilities Lease liabilities 20,201 23,533 Lease liabilities, noncurrent 66,733 85,275
Schedule of Lease Cost and Supplemental Cash Flow Information	The following table presents information about leases on our consolidated statements of operations (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating lease expense $ 5,455 $ 6,573 $ 16,583 $ 19,590 Short-term lease expense 130 128 386 451 Variable lease expense 1,297 1,412 3,759 4,614 Sublease income (450) (422) (1,324) (1,281) The following table presents supplemental cash flow information about our leases (in thousands): Nine Months Ended September 30, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 20,460 $ 24,029 Operating lease assets obtained in exchange for new lease liabilities 4,452 14,960

Goodwill and Acquired Intangi_2

Goodwill and Acquired Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the nine months ended September 30, 2021 are as follows (in thousands): Balance as of December 31, 2020 $ 169,662 Goodwill acquired 7,103 Balance as of September 30, 2021 $ 176,765
Summary of Intangible Assets Acquired	Acquired intangible assets subject to amortization consist of the following (in thousands): As of September 30, 2021 Cost Accumulated Net Weighted Average Remaining Useful Life (In years) Developed technology $ 28,000 $ (12,528) $ 15,472 3.3 Customer relationships 14,300 (7,591) 6,709 3.4 $ 42,300 $ (20,119) $ 22,181 As of December 31, 2020 Cost Accumulated Net Weighted Average Remaining Useful Life (In years) Developed technology $ 30,200 $ (12,445) $ 17,755 4.1 Customer relationships 14,710 (6,076) 8,634 4.0 Backlog 3,200 (3,033) 167 0.3 $ 48,110 $ (21,554) $ 26,556
Summary of Estimated Future Amortization Expense	Estimated future amortization expense as of September 30, 2021 is as follows (in thousands): Remainder of 2021 $ 1,861 2022 7,279 2023 6,583 2024 4,839 2025 972 Thereafter 647 $ 22,181

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Net Carrying Amount of Liability and Equity Component of Convertible Notes	The net carrying amount of the liability component of the 2025 Notes is as follows (in thousands): September 30, December 31, Principal $ 1,150,000 $ 1,150,000 Unamortized Debt Discount (168,392) (198,857) Unamortized issuance costs (13,420) (15,567) Net carrying amount $ 968,188 $ 935,576 The net carrying amount of the equity component of the 2025 Notes is as follows (in thousands): September 30, December 31, Debt Discount for Conversion Option $ 220,061 $ 220,061 Issuance costs (4,035) (4,035) Net carrying amount $ 216,026 $ 216,026 The net carrying amount of the liability component of the 2023 Notes is as follows (in thousands): September 30, December 31, Principal $ 149,194 $ 149,194 Unamortized Debt Discount (10,362) (15,394) Unamortized issuance costs (971) (1,412) Net carrying amount $ 137,861 $ 132,388 The net carrying amount of the equity component of the 2023 Notes is as follows (in thousands): September 30, December 31, Debt Discount for Conversion Option $ 32,427 $ 32,427 Issuance costs (765) (765) Net carrying amount $ 31,662 $ 31,662 The net impact to our stockholders ’ equity, included in additional paid-in capital, of the above components of the 2023 Notes is as follows (in thousands): At Issuance Conversion Option $ 124,976 Purchase of Capped Calls (63,940) Issuance Costs (2,948) Net deferred tax liability (13,784) Total $ 44,304
Schedule of Interest Expense	The interest expense related to the 2025 Notes is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Contractual interest expense $ 1,797 $ 1,797 $ 5,391 $ 2,076 Amortization of Debt Discount 10,281 9,785 30,465 11,297 Amortization of issuance costs 735 660 2,147 761 Total interest expense $ 12,813 $ 12,242 $ 38,003 $ 14,134 The interest expense related to the 2023 Notes is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Contractual interest expense $ 93 $ 93 $ 279 $ 770 Amortization of Debt Discount 1,699 1,614 5,032 13,097 Amortization of issuance costs 151 135 441 1,075 Total interest expense $ 1,943 $ 1,842 $ 5,752 $ 14,942

Common Stock and Stockholders_2

Common Stock and Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Summary of Stock Option and RSU Award Activity	A summary of restricted stock unit (“RSU”) activity for the nine months ended September 30, 2021 is as follows (in thousands, except per share information): Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Unvested — January 1, 2021 5,141 $ 75.93 Granted 1,835 147.67 Vested (1,796) 68.49 Forfeited or canceled (742) 86.86 Unvested — September 30, 2021 4,438 $ 106.77 A summary of stock option activity for the nine months ended September 30, 2021 is as follows (in thousands, except per share information): Stock Options Number of Weighted Weighted Aggregate (In years) Outstanding — January 1, 2021 4,235 $ 31.42 5.2 $ 473,358 Granted 411 148.05 Exercised (820) 23.02 Forfeited or canceled (118) 97.88 Outstanding — September 30, 2021 3,708 $ 44.09 5.0 $ 280,266

Deferred Revenue and Performa_2

Deferred Revenue and Performance Obligations (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Changes in Balance of Deferred Revenue	The changes in the balances of deferred revenue are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Balance, beginning of period $ 442,463 $ 316,113 $ 383,358 $ 323,962 Billings 352,580 273,464 1,027,949 749,755 Subscription and services revenue (327,812) (249,052) (912,665) (707,715) Other revenue* (19,162) (12,874) (50,573) (38,351) Balance, end of period $ 448,069 $ 327,651 $ 448,069 $ 327,651 *Other revenue primarily includes implementation and training services, Talk usage, and amounts from contract assets.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
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 Nine Months Ended 2021 2020 2021 2020 Net loss $ (54,417) $ (40,703) $ (161,789) $ (148,142) Weighted-average shares used to compute basic and diluted net loss per share 120,164 115,809 119,050 114,653 Net loss per share, basic and diluted $ (0.45) $ (0.35) $ (1.36) $ (1.29)
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 September 30, 2021 2020 Shares subject to outstanding common stock options and employee stock purchase plan 3,894 4,607 Restricted stock units 4,438 5,171 Shares related to convertible senior notes 2,883 770 11,215 10,548

Geographic Information (Tables)

Geographic Information (Tables)	9 Months Ended
	Sep. 30, 2021
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 Nine Months Ended 2021 2020 2021 2020 United States $ 174,264 $ 136,491 $ 489,476 $ 391,025 EMEA 102,889 73,798 282,323 210,487 APAC 35,730 28,954 98,700 81,105 Other 34,091 22,683 92,739 63,449 Total $ 346,974 $ 261,926 $ 963,238 $ 746,066
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 $ 61,317 $ 76,383 EMEA: Republic of Ireland 35,123 38,010 Other EMEA 6,837 5,784 Total EMEA 41,960 43,794 APAC: Singapore 14,786 19,560 Other APAC 6,643 6,466 Total APAC 21,429 26,026 Other 3,361 344 Total $ 128,067 $ 146,547

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($) $ in Thousands	Oct. 28, 2021	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Increase in goodwill		$ 176,765	$ 169,662
Cleverly Lda.
Business Acquisition [Line Items]
Increase in goodwill		7,000
Cleverly Lda. | Developed technology
Business Acquisition [Line Items]
Increase in developed technology		$ 1,000
Milky Way | Subsequent Event
Business Acquisition [Line Items]
Entity shares issued per acquiree share (in shares)	0.225
Fee payable upon termination of transaction	$ 150,000

Financial Instruments - Financi

Financial Instruments - Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Included in marketable securities	$ 1,012,481	$ 994,271
Fair value measurements, recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	1,291,851	1,189,125
Included in cash and cash equivalents	279,370	194,854
Included in marketable securities	1,012,481	994,271
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	413,386	366,638
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	401,614	431,087
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	279,370	162,156
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	104,765	101,239
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	51,684	80,394
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	33,687	36,954
Fair value measurements, recurring | Certificates of deposit and time deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	7,345	10,657
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	279,370	162,156
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 | U.S. Treasury securities
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 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	279,370	162,156
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	0
Fair value measurements, recurring | Level 1 | Agency securities
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 | Commercial paper
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 | Certificates of deposit and time deposits
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 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	1,012,481	1,026,969
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	413,386	366,638
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	401,614	431,087
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
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	104,765	101,239
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	51,684	80,394
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	33,687	36,954
Fair value measurements, recurring | Level 2 | Certificates of deposit and time deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	$ 7,345	$ 10,657

Financial Instruments - Narrati

Financial Instruments - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019	Mar. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gross unrealized gains			$ 3,000,000		$ 6,000,000
Gross unrealized losses			0		0
Amortized cost of cash equivalents and marketable securities	$ 1,289,000,000		1,289,000,000		1,183,000,000
Accrued interest	3,000,000		3,000,000		3,000,000
Aggregate fair value of securities with unrealized losses	292,000,000		292,000,000		107,000,000
Allowance for credit losses	0		0		0
Balance of strategic investment	12,000,000		12,000,000		11,000,000
Adjustments to carrying value of strategic investments			0
Realized gain from sale of strategic investment	1,000,000
Unrecognized loss related to effective portion of changes in fair value of foreign currency forward contracts	$ 468,276,000	$ 430,119,000	$ 468,276,000	$ 430,119,000	431,831,000	$ 464,127,000	$ 410,310,000	$ 457,984,000
Closing price of common stock (in usd per share)	$ 116.39		$ 116.39
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial assets	$ 0		$ 0		0
Convertible debt | Convertible senior notes due 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate	0.25%		0.25%						0.25%
Aggregate principal amount	$ 126,000,000		$ 126,000,000						$ 575,000,000
Convertible debt | Convertible senior notes due 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate	0.625%		0.625%				0.625%
Aggregate principal amount	$ 81,000,000		$ 81,000,000				$ 1,150,000,000
Convertible debt | Level 2 | Convertible senior notes due 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	1,440,000,000		1,440,000,000
Convertible debt | Level 2 | Convertible senior notes due 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	283,000,000		$ 283,000,000
Foreign currency forward contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative, maximum maturity			15 months
Reclassification of net gain into earnings over next 12 months	(7,000,000)		$ (7,000,000)
Notional value	452,000,000		452,000,000		$ 345,000,000
Loss recognized in AOCI	(4,000,000)	$ 1,000,000	(7,000,000)	$ (3,000,000)
Foreign currency forward contracts | AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrecognized loss related to effective portion of changes in fair value of foreign currency forward contracts	$ (6,000,000)		$ (6,000,000)

Financial Instruments - Marketa

Financial Instruments - Marketable Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Due in one year or less	$ 421,328	$ 565,593
Due after one year and within five years	591,153	428,678
Total	$ 1,012,481	$ 994,271

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments on Consolidated Balance Sheets (Details) - Designated as hedging instrument - Level 2 - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivatives Fair Value [Line Items]
Asset Derivatives	$ 5,268	$ 7,922
Liability Derivatives	9,874	5,768
Foreign currency forward contracts | Other current assets
Derivatives Fair Value [Line Items]
Asset Derivatives	5,268	7,922
Foreign currency forward contracts | Accrued liabilities
Derivatives Fair Value [Line Items]
Liability Derivatives	$ 9,874	$ 5,768

Financial Instruments - Sched_2

Financial Instruments - Schedule of Derivative Instruments on Statement of Operations (Details) - Foreign currency forward contracts - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	$ (1,527)	$ 911	$ 1,065	$ (1,874)
Revenue
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	(1,126)	100	(3,207)	1,222
Cost of revenue
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	(76)	163	814	(701)
Research and development
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	(92)	174	911	(671)
Sales and marketing
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	(180)	366	1,893	(1,350)
General and administrative
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Earnings	$ (53)	$ 108	$ 654	$ (374)

Costs to Obtain Customer Cont_2

Costs to Obtain Customer Contracts (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Deferred costs to obtain customer contracts	$ 134,000,000		$ 134,000,000		$ 105,000,000
Amortization of deferred costs	18,000,000	$ 12,000,000	48,739,000	$ 32,390,000
Impairment related to deferred costs	$ 0	$ 0	$ 0	$ 0

Property and Equipment - Compon

Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total	$ 207,547	$ 197,641
Less: accumulated depreciation and amortization	(114,024)	(103,433)
Property and equipment, net	93,523	94,208
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	79,702	91,205
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Total	57,849	48,730
Computer equipment and licensed software and patents
Property, Plant and Equipment [Line Items]
Total	37,871	30,725
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total	14,644	13,759
Construction in progress
Property, Plant and Equipment [Line Items]
Total	$ 17,481	$ 13,222

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 6	$ 7	$ 17	$ 20
Amortization expense of capitalized internal-use software	2	$ 2	5	$ 5
Carrying value of capitalized internal-use software	39		39		$ 32
Capitalized internal-use software included in construction in progress	$ 16		$ 16		$ 13

Leases - Schedule of Lease Impa

Leases - Schedule of Lease Impact on Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Lease right-of-use assets	$ 73,094	$ 84,013
Liabilities
Lease liabilities	20,201	23,533
Lease liabilities, noncurrent	$ 66,733	$ 85,275

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term			5 years 9 months 18 days
Weighted average discount rate			4.60%
Termination payment	$ 7
General and administrative
Lessee, Lease, Description [Line Items]
Aggregate impairment charge		$ 15

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease expense	$ 5,455	$ 6,573	$ 16,583	$ 19,590
Short-term lease expense	130	128	386	451
Variable lease expense	1,297	1,412	3,759	4,614
Sublease income	$ (450)	$ (422)	$ (1,324)	$ (1,281)

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 20,460	$ 24,029
Operating lease assets obtained in exchange for new lease liabilities	$ 4,452	$ 14,960

Goodwill and Acquired Intangi_3

Goodwill and Acquired Intangible Assets - Schedule of Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2020	$ 169,662
Goodwill acquired	7,103
Balance as of September 30, 2021	$ 176,765

Goodwill and Acquired Intangi_4

Goodwill and Acquired Intangible Assets - Acquired Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Cost	$ 42,300	$ 48,110
Accumulated Amortization	(20,119)	(21,554)
Net	22,181	26,556
Developed technology
Finite Lived Intangible Assets [Line Items]
Cost	28,000	30,200
Accumulated Amortization	(12,528)	(12,445)
Net	$ 15,472	$ 17,755
Weighted Average Remaining Useful Life	3 years 3 months 18 days	4 years 1 month 6 days
Customer relationships
Finite Lived Intangible Assets [Line Items]
Cost	$ 14,300	$ 14,710
Accumulated Amortization	(7,591)	(6,076)
Net	$ 6,709	$ 8,634
Weighted Average Remaining Useful Life	3 years 4 months 24 days	4 years
Backlog
Finite Lived Intangible Assets [Line Items]
Cost		$ 3,200
Accumulated Amortization		(3,033)
Net		$ 167
Weighted Average Remaining Useful Life		3 months 18 days

Goodwill and Acquired Intangi_5

Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 2	$ 2	$ 5	$ 7

Goodwill and Acquired Intangi_6

Goodwill and Acquired Intangible Assets - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2021	$ 1,861
2022	7,279
2023	6,583
2024	4,839
2025	972
Thereafter	647
Net	$ 22,181	$ 26,556

Convertible Senior Notes - Narr

Convertible Senior Notes - Narrative (Details) $ / shares in Units, shares in Millions	Mar. 31, 2018USD ($)$ / sharesshares	Jun. 30, 2020USD ($)day$ / sharesshares	Mar. 31, 2018USD ($)day$ / sharesshares	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Release of valuation allowance		$ 410,310,000		$ 468,276,000	$ 430,119,000	$ 468,276,000	$ 430,119,000	$ 464,127,000	$ 431,831,000	$ 457,984,000
Net proceeds used from offering to repurchase principal						0	1,128,990,000
Loss on early extinguishment of debt				0	0	0	25,950,000
Cost incurred related to capped calls							216,026,000
Additional Paid-In Capital
Debt Instrument [Line Items]
Release of valuation allowance		1,212,471,000		1,553,846,000	$ 1,273,242,000	1,553,846,000	1,273,242,000	$ 1,492,117,000	1,344,337,000	$ 1,155,044,000
Cost incurred related to capped calls							$ 216,026,000
Cumulative effect, period of adoption, adjustment | Additional Paid-In Capital
Debt Instrument [Line Items]
Release of valuation allowance									51,000,000
Convertible debt | Convertible senior notes due 2025
Debt Instrument [Line Items]
Aggregate principal amount		$ 1,150,000,000		$ 81,000,000		$ 81,000,000
Interest rate		0.625%		0.625%		0.625%
Proceeds from issuance of convertible senior notes, net of issuance costs		$ 1,129,000,000
Initial conversion rate of common stock		0.0091944
Conversion price (in usd per share) | $ / shares		$ 108.76
Limitation on sale of common stock, sale price threshold, number of trading days | day		20
Limitation on sale of common stock, sale price threshold, trading period | day		30
Threshold percentage of stock price trigger		130.00%
Number of consecutive business days		5 days
Percentage of closing sale price in excess of convertible notes		98.00%
Redemption price percentage		100.00%
Conversion Option		$ 220,000,000		$ 220,061,000		$ 220,061,000			220,061,000
Effective interest rate				5.00%		5.00%
Debt issuance costs, gross		21,000,000
Issuance costs attributable to the liability component		17,000,000		$ 13,420,000		$ 13,420,000			15,567,000
Net deferred tax liability related to cap call		$ 51,000,000
Capped calls, initial cap price (in usd per share) | $ / shares		$ 164.17
Number of shares covered by cap call (in shares) | shares		10.6
Net proceeds used from offering to repurchase principal		$ 618,000,000
Payments to repurchase convertible debt		426,000,000
Proceeds from convertible debt allocated to debt component		393,000,000
Proceeds from convertible debt allocated to equity component		225,000,000
Net carrying amount of liability component				968,188,000		968,188,000			935,576,000
Repayment of debt discount		39,000,000
Principal outstanding				1,150,000,000		1,150,000,000			1,150,000,000
Cost incurred related to capped calls		$ (130,000,000)
Convertible debt | Convertible senior notes due 2023
Debt Instrument [Line Items]
Aggregate principal amount	$ 575,000,000		$ 575,000,000	$ 126,000,000		$ 126,000,000
Interest rate	0.25%		0.25%	0.25%		0.25%
Proceeds from issuance of convertible senior notes, net of issuance costs			$ 561,000,000
Initial conversion rate of common stock			0.0158554
Conversion price (in usd per share) | $ / shares	$ 63.07		$ 63.07
Limitation on sale of common stock, sale price threshold, number of trading days | day			20
Limitation on sale of common stock, sale price threshold, trading period | day			30
Threshold percentage of stock price trigger			130.00%
Number of consecutive business days			5 days
Percentage of closing sale price in excess of convertible notes			98.00%
Redemption price percentage			100.00%
Conversion Option	$ 124,976,000		$ 124,976,000	$ 32,427,000		$ 32,427,000			32,427,000
Effective interest rate				5.26%		5.26%
Issuance costs attributable to the liability component				$ 971,000		$ 971,000			1,412,000
Net deferred tax liability related to cap call	$ 13,784,000		$ 13,784,000
Capped calls, initial cap price (in usd per share) | $ / shares	$ 95.20		$ 95.20
Number of shares covered by cap call (in shares) | shares	9.1		9.1	2.4		2.4
Net carrying amount of liability component	$ 367,000,000		$ 367,000,000	$ 137,861,000		$ 137,861,000			132,388,000
Loss on early extinguishment of debt			26,000,000
Principal outstanding				$ 149,194,000		$ 149,194,000			$ 149,194,000
Cost incurred related to capped calls	$ 44,304,000		$ (64,000,000)
Number of shares terminated (in shares) | shares		6.7
Proceeds from shares terminated		$ 83,000,000

Convertible Senior Notes - Sche

Convertible Senior Notes - Schedule of Net Carrying Amount of Liability and Equity Component of Convertible Notes (Details) - Convertible debt - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2018
Convertible senior notes due 2025
Net Carrying Amount of Liability Component of Convertible Notes [Abstract]
Principal	$ 1,150,000	$ 1,150,000
Unamortized Debt Discount	(168,392)	(198,857)
Unamortized issuance costs	(13,420)	(15,567)	$ (17,000)
Net carrying amount	968,188	935,576
Net Carrying Amount of Equity Component of Convertible Notes [Abstract]
Debt Discount for Conversion Option	220,061	220,061	$ 220,000
Issuance costs	(4,035)	(4,035)
Net carrying amount	216,026	216,026
Convertible senior notes due 2023
Net Carrying Amount of Liability Component of Convertible Notes [Abstract]
Principal	149,194	149,194
Unamortized Debt Discount	(10,362)	(15,394)
Unamortized issuance costs	(971)	(1,412)
Net carrying amount	137,861	132,388		$ 367,000
Net Carrying Amount of Equity Component of Convertible Notes [Abstract]
Debt Discount for Conversion Option	32,427	32,427		124,976
Issuance costs	(765)	(765)		$ (2,948)
Net carrying amount	$ 31,662	$ 31,662

Convertible Senior Notes - Sc_2

Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Total interest expense	$ 14,762	$ 14,087	$ 43,768	$ 29,060
Convertible debt | Convertible senior notes due 2025
Debt Instrument [Line Items]
Contractual interest expense	1,797	1,797	5,391	2,076
Amortization of Debt Discount	10,281	9,785	30,465	11,297
Amortization of issuance costs	735	660	2,147	761
Total interest expense	12,813	12,242	38,003	14,134
Convertible debt | Convertible senior notes due 2023
Debt Instrument [Line Items]
Contractual interest expense	93	93	279	770
Amortization of Debt Discount	1,699	1,614	5,032	13,097
Amortization of issuance costs	151	135	441	1,075
Total interest expense	$ 1,943	$ 1,842	$ 5,752	$ 14,942

Convertible Senior Notes - Summ

Convertible Senior Notes - Summary of Impact to Stockholder's Equity (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Net impact to stockholder's equity			$ 216,026
Convertible debt | Convertible senior notes due 2023
Debt Instrument [Line Items]
Conversion Option	$ 124,976	$ 124,976		$ 32,427	$ 32,427
Purchase of Capped Calls	(63,940)
Issuance Costs	(2,948)	(2,948)		$ (765)	$ (765)
Net deferred tax liability	(13,784)	(13,784)
Net impact to stockholder's equity	$ 44,304	$ (64,000)

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	1 Months Ended
	Apr. 30, 2021USD ($)	Jun. 02, 2020complaint	Nov. 07, 2019complaint
Ho v. Zendesk And Reidinger v. Zendesk
Other Commitments [Line Items]
Putative class action complaints			2
Anderson v. Svane
Other Commitments [Line Items]
Putative class action complaints		2
Cloud Infrastructure
Other Commitments [Line Items]
Total obligation | $	$ 64
Obligation period	3 years

Common Stock and Stockholders_3

Common Stock and Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Millions	Jan. 01, 2021shares	May 31, 2021shares	May 31, 2020shares	Sep. 30, 2021USD ($)$ / sharesshares	Jun. 30, 2021semi-annualTranche	Sep. 30, 2020USD ($)shares	Sep. 30, 2021USD ($)offeringPeriod$ / sharesshares	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2018shares	Dec. 31, 2020$ / sharesshares
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)				400,000,000			400,000,000			400,000,000
Common stock, par value (in usd per share) | $ / shares				$ 0.01			$ 0.01			$ 0.01
Common stock, shares issued (in shares)				120,500,000			120,500,000			117,500,000
Common stock, shares outstanding (in shares)				120,500,000			120,500,000			117,500,000
Preferred stock, shares authorized (in shares)				10,000,000			10,000,000			10,000,000
Preferred stock, par value (usd per share) | $ / shares				$ 0.01			$ 0.01			$ 0.01
Preferred stock, shares issued (in shares)				0			0			0
Preferred stock, shares outstanding (in shares)				0			0			0
Intrinsic value of options exercised (in usd per share) | $							$ 94	$ 54
Weighted-average grant date fair value of stock options (in usd per share) | $ / shares							$ 52.60	$ 31.41
Future period share-based compensation expense | $				$ 477			$ 477
Future period share-based compensation expense, period to recognized							2 years 8 months 12 days
Employee stock option
Class Of Stock [Line Items]
Offering period							18 months
Number of offering periods | offeringPeriod							3
Length of purchase period							6 months
Restricted stock units
Class Of Stock [Line Items]
Intrinsic value of shares vested | $							$ 249	$ 168
Shares granted (in shares)							1,835,000
Number of shares vested (in shares)							1,796,000
Employee stock
Class Of Stock [Line Items]
Share-based compensation expense, accelerated cost | $							$ 2
Performance restricted stock units
Class Of Stock [Line Items]
Number of vesting periods | semi-annualTranche					4
2009 Stock Option and Grant Plan
Class Of Stock [Line Items]
Shares of common stock available for issuance (in shares)				0			0
2014 Plan | Employee stock option
Class Of Stock [Line Items]
Increase in authorized shares (in shares)	5,900,000
Shares of common stock available for issuance (in shares)				18,900,000			18,900,000
PSU Retention Plan | Performance restricted stock units
Class Of Stock [Line Items]
Shares granted (in shares)									200,000
Share-based compensation expense | $				$ 0		$ 3	$ 1	$ 5
Number of shares vested (in shares)				0		36,000	37,000	62,000
Employee stock
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%
Number of shares repurchased under ESPP (in shares)		400,000	400,000
Increase in authorized shares (in shares)	1,200,000
Shares of common stock available for issuance (in shares)				5,600,000			5,600,000

Common Stock and Stockholders_4

Common Stock and Stockholders' Equity - Summary of Stock Option and RSU Award Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Number of Shares
Balance at the beginning of the period (in shares) | shares	4,235
Stock options granted (in shares) | shares	411
Stock options exercised (in shares) | shares	(820)
Stock options forfeited or canceled (in shares) | shares	(118)
Balance at the end of the period (in shares) | shares	3,708	4,235
Weighted Average Exercise Price
Balance at the beginning of the period (in usd per share) | $ / shares	$ 31.42
Stock options granted (in usd per share) | $ / shares	148.05
Stock options exercised (in usd per share) | $ / shares	23.02
Stock options forfeited or canceled (in usd per share) | $ / shares	97.88
Balance at the end of the period (in usd per share) | $ / shares	$ 44.09	$ 31.42
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term	5 years	5 years 2 months 12 days
Aggregate Intrinsic Value
Aggregate intrinsic value, options | $	$ 280,266	$ 473,358
Restricted stock units
Outstanding RSUs
Balance at the beginning of the period (in shares) | shares	5,141
RSUs granted (in shares) | shares	1,835
RSUs vested (in shares) | shares	(1,796)
RSUs forfeited or canceled (in shares) | shares	(742)
Balance at the end of the period (in shares) | shares	4,438	5,141
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in usd per share) | $ / shares	$ 75.93
Weighted average grant date fair value, RSUs granted (in usd per share) | $ / shares	147.67
Weighted average grant date fair value, RSUs vested (in usd per share) | $ / shares	68.49
Weighted average grant date fair value, RSUs forfeited or canceled (in usd per share) | $ / shares	86.86
Balance at the end of the period (in usd per share) | $ / shares	$ 106.77	$ 75.93

Deferred Revenue and Performa_3

Deferred Revenue and Performance Obligations - Schedule of Changes in Balance of Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Change in Balances of Deferred Revenue [Roll Forward]
Balance, beginning of period	$ 442,463	$ 316,113	$ 383,358	$ 323,962
Billings	352,580	273,464	1,027,949	749,755
Balance, end of period	448,069	327,651	448,069	327,651
Subscription and Services
Change in Balances of Deferred Revenue [Roll Forward]
Revenue recognized	(327,812)	(249,052)	(912,665)	(707,715)
Other Revenue
Change in Balances of Deferred Revenue [Roll Forward]
Revenue recognized	$ (19,162)	$ (12,874)	$ (50,573)	$ (38,351)

Deferred Revenue and Performa_4

Deferred Revenue and Performance Obligations - Performance Obligations (Details) $ in Millions	Sep. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 1,167
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 783
Performance obligations expected to be satisfied, expected timing	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01 | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, expected timing	13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01 | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, expected timing	36 months

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (54,417)	$ (40,703)	$ (161,789)	$ (148,142)
Weighted-average shares used to compute net loss per share, basic (in shares)	120,164	115,809	119,050	114,653
Weighted-average shares used to compute net loss per share, diluted (in shares)	120,164	115,809	119,050	114,653
Net loss per share, basic (in usd per share)	$ (0.45)	$ (0.35)	$ (1.36)	$ (1.29)
Net loss per share, diluted (in usd per share)	$ (0.45)	$ (0.35)	$ (1.36)	$ (1.29)

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	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	11,215	10,548
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)	3,894	4,607
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)	4,438	5,171
Shares related to convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	2,883	770

Net Loss Per Share - Narrative

Net Loss Per Share - Narrative (Details) - $ / shares shares in Millions	9 Months Ended
	Sep. 30, 2021	Jun. 30, 2020	Mar. 31, 2018
Convertible senior notes due 2023
Debt Instrument [Line Items]
Potential dilution based on initial conversion price (in shares)	2.4
Convertible senior notes due 2025
Debt Instrument [Line Items]
Potential dilution based on initial conversion price (in shares)	10.6
Convertible debt | Convertible senior notes due 2023
Debt Instrument [Line Items]
Conversion price (in usd per share)			$ 63.07
Convertible debt | Convertible senior notes due 2025
Debt Instrument [Line Items]
Conversion price (in usd per share)		$ 108.76

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 3,133	$ 1,973	$ 7,842	$ 4,777

Geographic Information - Narrat

Geographic Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2021segment
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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 346,974	$ 261,926	$ 963,238	$ 746,066
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	174,264	136,491	489,476	391,025
EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	102,889	73,798	282,323	210,487
APAC
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	35,730	28,954	98,700	81,105
Other
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 34,091	$ 22,683	$ 92,739	$ 63,449

Geographic Information - Sche_2

Geographic Information - Schedule of Long-Lived Assets by Geographic Areas (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	$ 128,067	$ 146,547
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	61,317	76,383
EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	41,960	43,794
Republic of Ireland
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	35,123	38,010
Other EMEA
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	6,837	5,784
APAC
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	21,429	26,026
Singapore
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	14,786	19,560
Other APAC
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	6,643	6,466
Other
Revenues From External Customers And Long Lived Assets [Line Items]
Long-lived assets	$ 3,361	$ 344