Twilio (TWLO) 10-Q 28 Oct 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 22, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Annual Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-37806
Entity Registrant Name	TWILIO INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-2574840
Entity Address, Address Line One	101 Spear Street
Entity Address, Address Line Two	First Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	390-2337
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	TWLO
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001447669
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Common Stock Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		168,448,610
Common Stock Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		9,880,181

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,497,498	$ 933,885
Short-term marketable securities	3,896,754	2,105,906
Accounts receivable, net	345,793	251,167
Prepaid expenses and other current assets	165,760	81,377
Total current assets	5,905,805	3,372,335
Property and equipment, net	237,241	183,239
Operating right-of-use asset	248,582	258,610
Intangible assets, net	1,102,599	966,573
Goodwill	5,263,051	4,595,394
Other long-term assets	219,569	111,282
Total assets	12,976,847	9,487,433
Current liabilities:
Accounts payable	76,293	60,042
Accrued expenses and other current liabilities	368,683	252,895
Deferred revenue and customer deposits	121,337	87,031
Operating lease liability, current	50,760	48,338
Total current liabilities	617,073	448,306
Operating lease liability, noncurrent	223,033	229,905
Finance lease liability, noncurrent	20,254	17,856
Long-term debt	985,547	302,068
Other long-term liabilities	49,191	36,633
Total liabilities	1,895,098	1,034,768
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock	0	0
Class A and Class B common stock	178	164
Additional paid-in capital	12,910,271	9,613,246
Accumulated other comprehensive income	(405)	9,046
Accumulated deficit	(1,828,295)	(1,169,791)
Total stockholders’ equity	11,081,749	8,452,665
Total liabilities and stockholders’ equity	$ 12,976,847	$ 9,487,433

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Revenue	$ 740,176	$ 447,969	$ 1,999,095	$ 1,213,686
Cost of revenue	375,561	217,095	1,004,929	580,146
Gross profit	364,615	230,874	994,166	633,540
Operating expenses:
Research and development	209,890	136,652	565,970	371,692
Sales and marketing	264,548	140,875	713,196	387,420
General and administrative	122,522	65,617	346,958	182,038
Total operating expenses	596,960	343,144	1,626,124	941,150
Loss from operations	(232,345)	(112,270)	(631,958)	(307,610)
Other expenses, net	(6,613)	(3,996)	(39,219)	(2,099)
Loss before benefit (provision) for income taxes	(238,958)	(116,266)	(671,177)	(309,709)
Benefit (provision) for income taxes	14,849	(648)	12,673	(1,919)
Net loss attributable to common stockholders	$ (224,109)	$ (116,914)	$ (658,504)	$ (311,628)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (1.26)	$ (0.79)	$ (3.82)	$ (2.18)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (1.26)	$ (0.79)	$ (3.82)	$ (2.18)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic (in shares)	177,231,285	147,501,075	172,605,371	142,832,021
Weighted-average shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	177,231,285	147,501,075	172,605,371	142,832,021

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - 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	$ (224,109)	$ (116,914)	$ (658,504)	$ (311,628)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities	(982)	(3,021)	(6,137)	5,499
Foreign currency translation	31	0	(245)	0
Net change in market value of effective foreign currency forward exchange contracts	(161)	0	(3,069)	0
Total other comprehensive (loss) income	(1,112)	(3,021)	(9,451)	5,499
Comprehensive loss attributable to common stockholders	$ (225,221)	$ (119,935)	$ (667,955)	$ (306,129)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders Equity (Unaudited) - USD ($) $ in Thousands	Total	Common StockCommon Stock Class A	Common StockCommon Stock Class B	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance (in shares) at Dec. 31, 2019		126,882,172	11,530,627
Balance at Dec. 31, 2019	$ 4,279,411	$ 124	$ 14	$ 4,952,999	$ 5,086	$ (678,812)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(94,791)					(94,791)
Exercises of vested stock options (in shares)		243,029	426,001
Exercises of vested stock options	8,231			8,231
Vesting of restricted stock units (in shares)		849,763	23,107
Vesting of restricted stock units	1	$ 1
Value of equity awards withheld for tax liability (in shares)		(8,726)	(4,692)
Value of equity awards withheld for tax liability	(1,674)			(1,674)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		618,103	(618,103)
Conversion of shares of Class B common stock into shares of Class A common stock		$ 1	$ (1)
Donated common stock (in shares)		22,102
Donated common stock	2,701			2,701
Unrealized (loss) gain on marketable securities	(9,375)				(9,375)
Stock-based compensation	72,021			72,021
Balance (in shares) at Mar. 31, 2020		128,606,443	11,356,940
Balance at Mar. 31, 2020	4,256,525	$ 126	$ 13	5,034,278	(4,289)	(773,603)
Balance (in shares) at Dec. 31, 2019		126,882,172	11,530,627
Balance at Dec. 31, 2019	4,279,411	$ 124	$ 14	4,952,999	5,086	(678,812)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(311,628)
Unrealized (loss) gain on marketable securities	5,499
Foreign currency translation	0
Net change in market value of effective foreign currency forward exchange contracts	0
Balance (in shares) at Sep. 30, 2020		140,173,591	10,729,264
Balance at Sep. 30, 2020	5,762,268	$ 138	$ 12	6,741,973	10,585	(990,440)
Balance (in shares) at Mar. 31, 2020		128,606,443	11,356,940
Balance at Mar. 31, 2020	4,256,525	$ 126	$ 13	5,034,278	(4,289)	(773,603)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(99,923)					(99,923)
Exercises of vested stock options (in shares)		1,590,891	459,010
Exercises of vested stock options	45,232	$ 2		45,230
Vesting of restricted stock units (in shares)		807,270	4,212
Vesting of restricted stock units	1	$ 1
Value of equity awards withheld for tax liability (in shares)		(6,018)
Value of equity awards withheld for tax liability	(1,144)			(1,144)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		983,005	(983,005)
Conversion of shares of Class B common stock into shares of Class A common stock		$ 1	$ (1)
Shares issued under ESPP (in shares)		190,642
Shares issued under ESPP	16,473			16,473
Donated common stock (in shares)		22,102
Donated common stock	3,972			3,972
Unrealized (loss) gain on marketable securities	17,895				17,895
Stock-based compensation	82,559			82,559
Balance (in shares) at Jun. 30, 2020		132,194,335	10,837,157
Balance at Jun. 30, 2020	4,321,590	$ 130	$ 12	5,181,368	13,606	(873,526)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(116,914)					(116,914)
Exercises of vested stock options (in shares)		218,555	173,199
Exercises of vested stock options	9,221			9,221
Vesting of restricted stock units (in shares)		926,032	1,688
Vesting of restricted stock units	1	$ 1		0
Value of equity awards withheld for tax liability (in shares)		(5,870)
Value of equity awards withheld for tax liability	(1,409)			(1,409)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		282,780	(282,780)
Equity component from partial settlement of 2023 convertible senior notes (in shares)		715,819
Equity component from partial settlement of 2023 convertible senior notes	46,155	$ 1		46,154
Donated common stock (in shares)		22,102
Donated common stock	5,757			5,757
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts (in shares)		5,819,838
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts	1,408,750	$ 6		1,408,744
Costs related to the follow-on public offering	(541)			(541)
Unrealized (loss) gain on marketable securities	(3,021)				(3,021)
Foreign currency translation	0
Net change in market value of effective foreign currency forward exchange contracts	0
Stock-based compensation	92,679			92,679
Balance (in shares) at Sep. 30, 2020		140,173,591	10,729,264
Balance at Sep. 30, 2020	5,762,268	$ 138	$ 12	6,741,973	10,585	(990,440)
Balance (in shares) at Dec. 31, 2020		153,496,222	10,551,302
Balance at Dec. 31, 2020	8,452,665	$ 151	$ 13	9,613,246	9,046	(1,169,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(206,542)					(206,542)
Exercises of vested stock options (in shares)		248,008	211,371
Exercises of vested stock options	11,564			11,564
Vesting of restricted stock units (in shares)		913,966
Vesting of restricted stock units		$ 1		(1)
Value of equity awards withheld for tax liability (in shares)		(6,989)
Value of equity awards withheld for tax liability	(2,774)			(2,774)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		419,371	(419,371)
Equity component from partial settlement of 2023 convertible senior notes (in shares)		1,158,381
Equity component from partial settlement of 2023 convertible senior notes	80,049	$ 2		80,047
Donated common stock (in shares)		22,102
Donated common stock	9,405			9,405
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts (in shares)		4,312,500
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts	1,766,400	$ 4		1,766,396
Costs related to the follow-on public offering	(727)			(727)
Issuance of restricted stock awards (in shares)		24,697
Unrealized (loss) gain on marketable securities	(4,176)				(4,176)
Foreign currency translation	(210)				(210)
Stock-based compensation	141,542			141,542
Balance (in shares) at Mar. 31, 2021		160,588,258	10,343,302
Balance at Mar. 31, 2021	10,247,196	$ 158	$ 13	11,618,698	4,660	(1,376,333)
Balance (in shares) at Dec. 31, 2020		153,496,222	10,551,302
Balance at Dec. 31, 2020	8,452,665	$ 151	$ 13	9,613,246	9,046	(1,169,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(658,504)
Unrealized (loss) gain on marketable securities	(6,137)
Foreign currency translation	(245)
Net change in market value of effective foreign currency forward exchange contracts	(3,069)
Balance (in shares) at Sep. 30, 2021		168,352,933	9,913,181
Balance at Sep. 30, 2021	11,081,749	$ 166	$ 12	12,910,271	(405)	(1,828,295)
Balance (in shares) at Mar. 31, 2021		160,588,258	10,343,302
Balance at Mar. 31, 2021	10,247,196	$ 158	$ 13	11,618,698	4,660	(1,376,333)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(227,853)					(227,853)
Exercises of vested stock options (in shares)		294,430	63,164
Exercises of vested stock options	20,351			20,351
Vesting of restricted stock units (in shares)		839,472
Vesting of restricted stock units		$ 1		(1)
Value of equity awards withheld for tax liability (in shares)		(5,498)
Value of equity awards withheld for tax liability	(1,882)			(1,882)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		188,044	(188,044)
Conversion of shares of Class B common stock into shares of Class A common stock		$ 1	$ (1)
Equity component from partial settlement of 2023 convertible senior notes (in shares)		3,688,584
Equity component from partial settlement of 2023 convertible senior notes	255,594	$ 4		255,590
Settlement of capped call, net of related costs	225,233			225,233
Shares issued under ESPP (in shares)		100,107
Shares issued under ESPP	23,699			23,699
Donated common stock (in shares)		22,102
Donated common stock	6,789			6,789
Costs related to the follow-on public offering	(50)			(50)
Unrealized (loss) gain on marketable securities	(979)				(979)
Foreign currency translation	(66)				(66)
Net change in market value of effective foreign currency forward exchange contracts	(2,908)				(2,908)
Stock-based compensation	148,988			148,988
Balance (in shares) at Jun. 30, 2021		165,715,499	10,218,422
Balance at Jun. 30, 2021	10,694,112	$ 164	$ 12	12,297,415	707	(1,604,186)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(224,109)					(224,109)
Exercises of vested stock options (in shares)		222,066	83,484
Exercises of vested stock options	15,993			15,993
Vesting of restricted stock units (in shares)		834,148
Vesting of restricted stock units		$ 1		(1)
Value of equity awards withheld for tax liability (in shares)		(5,530)
Value of equity awards withheld for tax liability	(1,896)			(1,896)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)		388,725	(388,725)
Donated common stock (in shares)		22,102
Donated common stock	8,389			8,389
Costs related to the follow-on public offering	$ 90			90
Shares issued in acquisition (in shares)	1,116,390
Shares issued in acquisition	$ 419,037	$ 1		419,036
Value of equity awards assumed in acquisition	1,511			1,511
Shares issued in acquisition subject to future vesting (in shares)		59,533
Unrealized (loss) gain on marketable securities	(982)				(982)
Foreign currency translation	31				31
Net change in market value of effective foreign currency forward exchange contracts	(161)				(161)
Stock-based compensation	169,734			169,734
Balance (in shares) at Sep. 30, 2021		168,352,933	9,913,181
Balance at Sep. 30, 2021	$ 11,081,749	$ 166	$ 12	$ 12,910,271	$ (405)	$ (1,828,295)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (658,504)	$ (311,628)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	189,669	98,070
Non-cash reduction to the right-of-use asset	36,249	27,240
Net amortization of investment premium and discount	24,880	2,909
Amortization of debt discount and issuance costs	5,457	18,432
Stock-based compensation	445,366	237,822
Amortization of deferred commissions	20,798	8,556
Tax benefit related to release of valuation allowance	(15,569)	(716)
Allowance for credit losses	11,371	8,417
Value of donated common stock	24,583	12,430
Loss on extinguishment of debt	28,965	3,155
Other adjustments	8,626	(142)
Changes in operating assets and liabilities:
Accounts receivable	(81,186)	(58,340)
Prepaid expenses and other current assets	(59,929)	(8,733)
Other long-term assets	(66,501)	(64,777)
Accounts payable	(8,665)	86
Accrued expenses and other current liabilities	84,730	59,594
Deferred revenue and customer deposits	27,004	7,799
Operating lease liabilities	(36,274)	(25,161)
Other long-term liabilities	(1,019)	2,740
Net cash (used in) provided by operating activities	(19,949)	17,753
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired and other related payments	(490,880)	(2,786)
Purchases of marketable securities and other investments	(3,225,799)	(1,465,158)
Proceeds from sales and maturities of marketable securities	1,334,444	892,365
Capitalized software development costs	(35,926)	(26,114)
Purchases of long-lived and intangible assets	(33,575)	(19,252)
Net cash used in investing activities	(2,451,736)	(620,945)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from a public equity offering	1,766,400	1,408,750
Payments of costs related to public offerings	(464)	(433)
Proceeds from issuance of senior notes	987,500	0
Payments of debt issuance costs	(2,751)	0
Proceeds from settlement of capped call, net of settlement costs	228,412	0
Principal payments on debt and finance leases	(4,852)	(6,688)
Proceeds from exercises of stock options and shares issued in ESPP	71,607	79,157
Value of equity awards withheld for tax liabilities	(6,552)	(4,227)
Net cash provided by financing activities	3,039,300	1,476,559
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(157)	0
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	567,458	873,367
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Beginning of period	933,885	253,735
CASH, CASH EQUIVALENTS AND RESTRICTED CASH —End of period	1,501,343	1,127,102
Supplemental Cash Flow Information [Abstract]
Cash paid for income taxes, net	4,439	1,962
Cash paid for interest	19,545	1,290
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property, equipment and intangible assets, accrued but not paid	6,758	1,261
Purchases of property and equipment through finance leases	11,876	15,047
Value of common stock issued and stock awards assumed in acquisition	420,548	0
Value of common stock issued to settle convertible senior notes	1,704,969	171,840
Stock-based compensation capitalized in software development costs	14,938	10,711
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	1,497,498	1,127,102
Restricted cash in other current assets	2,733	0
Restricted cash in other long-term assets	1,112	0
Total cash, cash equivalents and restricted cash	$ 1,501,343	$ 1,127,102

Organization and Description of

Organization and Description of Business	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Twilio Inc. (the “Company”) was incorporated in the state of Delaware on March 13, 2008. The Company is the leading cloud communications platform and enables developers to build, scale and operate real-time customer engagement within their software applications via simple-to-use Application Programming Interfaces (“API”). The power, flexibility and reliability offered by the Company’s software building blocks empower entities of virtually every shape and size to build world-class engagement into their customer experience. The Company’s headquarters are located in San Francisco, California, and the Company has subsidiaries in Australia, Bermuda, Brazil, Canada, Colombia, Czech Republic, Estonia, France, Germany, Hong Kong, India, Ireland, Japan, Mexico, the Netherlands, Poland, Serbia, Singapore, Spain, Sweden, the United Kingdom and the United States.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on February 26, 2021 (“Annual Report”). The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but may not include all disclosures including certain notes required by U.S. GAAP on an annual reporting basis. In the opinion of management, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the 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 2021 or any future period. (b) Principles of Consolidation The condensed consolidated financial statements include the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. (c) Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates are used for, but not limited to, allowances for doubtful accounts and customer credit reserves; recoverability of long-lived and intangible assets; capitalization and useful life of the Company’s capitalized internal-use software development costs; fair value of acquired intangible assets and goodwill; accruals and contingencies. Estimates are based on historical experience and on various assumptions that the Company believes are reasonable under current circumstances. However, future events are subject to change and best estimates and judgments may require further adjustments; therefore, actual results could differ materially from those estimates. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. (d) Concentration of Credit Risk Financial instruments that potentially expose the Company to a concentration of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains cash, cash equivalents and marketable securities with financial institutions that management believes are financially sound and have minimal credit risk exposure although the balances will exceed insured limits. The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customer deteriorates substantially, the Company’s results of operations could be adversely affected. To reduce credit risk, management performs credit evaluations of the financial condition of significant customers. The Company does not require collateral from its credit customers and maintains reserves for estimated credit losses on customer accounts when considered necessary. Actual credit losses may differ from the Company’s estimates. During the three and nine months ended September 30, 2021 and 2020, no customer organization accounted for more than 10% of the Company’s total revenue. As of September 30, 2021 and December 31, 2020, no customer organization represented more than 10% of the Company’s gross accounts receivable. (e) Changes to Significant Accounting Policies Derivatives and Hedging The Company is exposed to a wide variety of risks arising from its business operations and overall economic conditions. These risks include exposure to fluctuations in various foreign currencies against its functional currency and can impact the value of cash receipts and payments. The Company minimizes its exposure to these risks through management of its core business activities, specifically, the amounts, sources and duration of its assets and liabilities, and the use of derivative financial instruments. In the second quarter of 2021, the Company started using foreign currency derivative forward contracts and in the future may also use foreign currency option contacts. Foreign currency derivative forward contracts involve fixing the exchange rate for delivery of a specified amount of foreign currency on a specified date. These agreements are typically cash settled in U.S. dollars for their fair value at or close to their settlement date. Foreign currency option contracts will require the Company to pay a premium for the right to sell a specified amount of foreign currency prior to the maturity date of the option. The Company does not enter into derivative financial instruments trading for speculative purposes. Derivative instruments are carried at fair value and recorded as either an asset or a liability until they mature. Gains and losses resulting from changes in fair value of these instruments are accounted for depending on the use of the derivative and whether it is designated and qualifies for hedge accounting. For derivative instruments designated as cash flow hedges, gains or losses are initially recorded in other comprehensive income (“OCI”) in the balance sheet, then reclassified into the statement of operations in the period in which the derivative instrument matures. These realized gains and losses are recorded within the same financial statement line item as the hedged transaction. The Company’s foreign currency derivative contracts are classified within Level 2 of the fair value hierarchy because the valuation inputs are based on quoted prices and market observable data of similar instruments in active markets, such as currency spot and forward rates. There have been no other changes to the Company’s significant accounting policies as described in its Annual Report.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial Assets The following tables provide the financial assets and liabilities measured at fair value on a recurring basis: Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 1,087,268 $ — $ — $ 1,087,268 $ — $ — $ 1,087,268 Commercial paper 74,209 — — — 74,209 — 74,209 Total included in cash and cash equivalents 1,161,477 — — 1,087,268 74,209 — 1,161,477 Marketable securities: U.S. Treasury securities 349,951 73 (353) 349,671 — — 349,671 Non-U.S. Government securities 242,258 4 (249) 242,013 — — 242,013 Corporate debt securities and commercial paper 3,302,309 4,141 (1,380) 27,000 3,278,070 — 3,305,070 Total marketable securities 3,894,518 4,218 (1,982) 618,684 3,278,070 — 3,896,754 Total financial assets $ 5,055,995 $ 4,218 $ (1,982) $ 1,705,952 $ 3,352,279 $ — $ 5,058,231 Financial Liabilities: Accrued expenses and other current liabilities: Foreign currency derivative liabilities $ — $ — $ (3,069) $ — $ (3,069) $ — $ (3,069) Total financial liabilities $ — $ — $ (3,069) $ — $ (3,069) $ — $ (3,069) Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 656,749 $ — $ — $ 656,749 $ — $ — $ 656,749 Commercial paper 2,000 — — — 2,000 — 2,000 Total included in cash and cash equivalents 658,749 — — 656,749 2,000 — 658,749 Marketable securities: U.S. Treasury securities 223,247 389 (1) 223,635 — — 223,635 Corporate debt securities and commercial paper 1,874,257 8,149 (135) 50,000 1,832,271 — 1,882,271 Total marketable securities 2,097,504 8,538 (136) 273,635 1,832,271 — 2,105,906 Total financial assets $ 2,756,253 $ 8,538 $ (136) $ 930,384 $ 1,834,271 $ — $ 2,764,655 The Company’s primary objective when investing excess cash is preservation of capital, hence the Company’s marketable securities primarily consist of U.S. Treasury Securities, high credit quality corporate debt securities and commercial paper. As the Company views its marketable securities as available to support current operations, it has classified all available for sale securities as short-term. As of September 30, 2021 and December 31, 2020, for fixed income securities that were in unrealized loss positions, the Company has determined that (i) it does not have the intent to sell any of these investments, and (ii) it is not more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. In addition, as of September 30, 2021 and December 31, 2020, the Company anticipates that it will recover the entire amortized cost basis of such fixed income securities before maturity. The Company regularly reviews changes to the rating of its debt securities by rating agencies as well as reasonably monitors the surrounding economic conditions to assess the risk of expected credit losses. As of September 30, 2021, the risk of expected credit losses was not significant. Interest earned on marketable securities was $16.2 million and $39.5 million in the three and nine months ended September 30, 2021, respectively, and $7.1 million and $23.7 million in the three and nine months ended September 30, 2020, respectively. The interest is recorded as other expenses, net, in the accompanying condensed consolidated statements of operations. The following table summarizes the contractual maturities of marketable securities: As of September 30, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,119,954 $ 1,121,537 $ 1,126,091 $ 1,128,927 One to three years 2,774,564 2,775,217 971,413 976,979 Total $ 3,894,518 $ 3,896,754 $ 2,097,504 $ 2,105,906 Strategic Investments As of September 30, 2021 and December 31, 2020, the Company held strategic investments with a carrying value of $66.3 million and $9.3 million, respectively, in equity securities of privately held companies and restricted equity securities of a publicly held company. The Company does not have a controlling interest in nor can it exercise significant influence over any of these companies. These securities are recorded as other long-term assets in the accompanying condensed consolidated balance sheets. There were no impairments or other adjustments recorded in the three and nine months ended September 30, 2021 or 2020. Financial Liabilities The Company’s financial liabilities that are not measured at fair value on a recurring basis consist of its senior notes due 2029 and 2031 (“2029 Notes” and “2031 Notes,” respectively). The Company’s convertible senior notes due 2023 (“Convertible Notes”) were fully redeemed in June 2021 and were no longer outstanding as of the end of the second quarter of 2021. Refer to Note 10 for further details on these financial liabilities. As of September 30, 2021, the fair values of the 2029 Notes and 2031 Notes were $512.9 million and $513.4 million, respectively. The 2029 Notes and 2031 Notes are classified as Level 2 financial instruments within the fair value hierarchy.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities As of September 30, 2021, the Company had outstanding foreign currency forward contracts designated as cash flow hedges with total buy and sell notional values of $63.4 million and $76.7 million, respectively. The notional value represents the amount that will be purchased or sold upon maturity of the forward contract. As of September 30, 2021, these contracts had maturities of less than 6 months and the $3.1 million fair value of the associated liability was recorded in accrued expenses and other current liabilities in the accompanying condensed consolidated balance sheet. Losses associated with these foreign currency forward contracts were as follows: Condensed Consolidated Statement of Operations and Statement of Comprehensive Loss Three Months Ended Nine Months Ended 2021 2021 (In thousands) Losses recognized in OCI Net change in market value of effective foreign currency forward exchange contracts $ (161) $ (3,069) Losses recognized in income due to instruments maturing Cost of revenue $ (2,464) $ (2,931)

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 consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 185,037 $ 142,489 Data center equipment (1) 64,104 43,477 Leasehold improvements 80,897 69,756 Office equipment 56,291 35,346 Furniture and fixtures (1) 15,646 12,312 Software 10,491 9,943 Total property and equipment 412,466 313,323 Less: accumulated depreciation and amortization (175,225) (130,084) Total property and equipment, net $ 237,241 $ 183,239 ____________________________________ ( 1 ) Data center equipment and furniture and fixtures contain assets under finance leases. See Note 6 for further detail. Supplemental depreciation and amortization disclosures are as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Depreciation and amortization expense $ 14,546 $ 12,843 $ 43,198 $ 36,674 Capitalized internal-use software development costs $ 17,999 $ 12,172 $ 49,527 $ 36,738 Stock based compensation costs included in capitalized internal-use software development costs $ 5,198 $ 3,696 $ 14,938 $ 10,711 Amortization of capitalized internal-use software development costs $ 4,419 $ 4,380 $ 13,270 $ 13,389

Right-of-Use Asset and Lease Li

Right-of-Use Asset and Lease Liabilities	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Right-of-Use Asset and Lease Liabilities	Right-of-Use Asset and Lease Liabilities The Company has entered into various operating lease agreements for office space and data centers and finance lease agreements for data center and office equipment and furniture. As of September 30, 2021, the Company had 32 leased properties with remaining lease terms ranging from 0.2 years to 8.0 years, some of which include options to extend the leases for up to 5.0 years. The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 16,141 $ 12,127 $ 45,519 $ 35,048 Finance lease cost: Amortization of assets 2,905 2,384 8,389 6,118 Interest on lease liabilities 282 212 805 604 Short-term lease cost 802 1,195 3,340 3,698 Variable lease cost 2,389 2,066 7,322 5,246 Total net lease cost $ 22,519 $ 17,984 $ 65,375 $ 50,714 Supplemental balance sheet information related to leases was as follows: As of As of September 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 248,582 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 29,027 25,771 Total leased assets $ 277,609 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 50,760 $ 48,338 Finance Finance lease liability, current 10,150 9,062 Noncurrent Operating Operating lease liability, noncurrent 223,033 229,905 Finance Finance lease liability, noncurrent 20,254 17,856 Total lease liabilities $ 304,197 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $88.9 million and $57.1 million as of September 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $23.4 million and $15.0 million as of September 30, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Nine Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 44,551 $ 34,124 Operating cash flows from finance leases (interest) $ 788 $ 604 Financing cash flows from finance leases $ 8,343 $ 5,721 Weighted average remaining lease term (in years): Operating leases 5.7 5.6 Finance leases 3.1 3.4 Weighted average discount rate: Operating leases 4.5 % 5.3 % Finance leases 3.5 % 4.1 % Maturities of lease liabilities were as follows: As of September 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining three months) $ 14,742 $ 2,920 2022 63,245 10,681 2023 55,476 9,934 2024 50,857 6,693 2025 37,706 1,394 Thereafter 89,223 518 Total lease payments 311,249 32,140 Less: imputed interest (37,456) (1,736) Total lease obligations 273,793 30,404 Less: current obligations (50,760) (10,150) Long-term lease obligations $ 223,033 $ 20,254
Right-of-Use Asset and Lease Liabilities	Right-of-Use Asset and Lease Liabilities The Company has entered into various operating lease agreements for office space and data centers and finance lease agreements for data center and office equipment and furniture. As of September 30, 2021, the Company had 32 leased properties with remaining lease terms ranging from 0.2 years to 8.0 years, some of which include options to extend the leases for up to 5.0 years. The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 16,141 $ 12,127 $ 45,519 $ 35,048 Finance lease cost: Amortization of assets 2,905 2,384 8,389 6,118 Interest on lease liabilities 282 212 805 604 Short-term lease cost 802 1,195 3,340 3,698 Variable lease cost 2,389 2,066 7,322 5,246 Total net lease cost $ 22,519 $ 17,984 $ 65,375 $ 50,714 Supplemental balance sheet information related to leases was as follows: As of As of September 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 248,582 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 29,027 25,771 Total leased assets $ 277,609 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 50,760 $ 48,338 Finance Finance lease liability, current 10,150 9,062 Noncurrent Operating Operating lease liability, noncurrent 223,033 229,905 Finance Finance lease liability, noncurrent 20,254 17,856 Total lease liabilities $ 304,197 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $88.9 million and $57.1 million as of September 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $23.4 million and $15.0 million as of September 30, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Nine Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 44,551 $ 34,124 Operating cash flows from finance leases (interest) $ 788 $ 604 Financing cash flows from finance leases $ 8,343 $ 5,721 Weighted average remaining lease term (in years): Operating leases 5.7 5.6 Finance leases 3.1 3.4 Weighted average discount rate: Operating leases 4.5 % 5.3 % Finance leases 3.5 % 4.1 % Maturities of lease liabilities were as follows: As of September 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining three months) $ 14,742 $ 2,920 2022 63,245 10,681 2023 55,476 9,934 2024 50,857 6,693 2025 37,706 1,394 Thereafter 89,223 518 Total lease payments 311,249 32,140 Less: imputed interest (37,456) (1,736) Total lease obligations 273,793 30,404 Less: current obligations (50,760) (10,150) Long-term lease obligations $ 223,033 $ 20,254

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business Combinations Zipwhip, Inc. In July 2021, the Company acquired all outstanding shares of Zipwhip, Inc. (“Zipwhip”), a leading provider of toll-free messaging in the United States, for a purchase price of $838.4 million. The purchase price included $418.0 million of cash, $419.0 million fair value of 1.1 million shares of the Company's Class A common stock and $1.5 million fair value of the pre-combination services of Zipwhip employees reflected in the unvested equity awards assumed by the Company at closing. Additionally, at closing, the Company issued 59,533 shares of its Class A common stock which are subject to vesting over a period of 3 years. Vesting of these shares will be recorded in the stock-based compensation expense. Part of the cash consideration paid at closing was to settle the vested equity awards of Zipwhip employees. The Company assumed all unvested and outstanding equity awards of Zipwhip continuing employees, as converted into its own equity awards, at the conversion ratio provided in the Agreement and Plan of Merger and Reorganization (the “Merger Agreement”). This transaction also included a $19.1 million of additional cash consideration for certain employees, which will vest as these employees provide services in the post-acquisition period. This amount will be recorded in the operating expenses over a period of 3 years as the services are provided. The acquisition was accounted for as a business combination and the total preliminary purchase price of $838.4 million was allocated to the net tangible and intangible assets and liabilities based on their preliminary fair values on the acquisition date with the excess recorded as goodwill. These estimates were derived from information currently available. The determination of the fair values and estimated lives of depreciable tangible and identifiable intangible assets requires significant judgment. As of September 30, 2021, the primary areas that are not yet finalized include determination of the purchase price, valuation of acquired intangible assets, contingencies and income and other taxes. The fair value of the 1.2 million aggregate number of shares of the Company's Class A common stock issued at closing was determined based on the closing market price of the Company's Class A common stock on the acquisition date. The fair value of the $30.7 million unvested equity awards assumed on the acquisition date was determined (a) for options, by using the Black-Scholes option pricing model with the applicable assumptions as of the acquisition date; (b) for restricted stock units, by using the closing market price of the Company's Class A common stock on the acquisition date. These awards will continue to vest as Zipwhip employees continue to provide services in the post-acquisition period. The fair value of these awards will be recorded into the stock-based compensation expense over the respective vesting period of each award. The purchase price components are summarized in the following table: Total (In thousands) Fair value of Class A common stock transferred $ 419,037 Cash consideration 417,900 Fair value of the pre-combination service through equity awards 1,511 Total purchase price $ 838,448 The following table presents the preliminary purchase price allocation recorded in the Company's consolidated balance sheet as of September 30, 2021: Total (In thousands) Cash and cash equivalents $ 21,610 Accounts receivable and other current assets 11,481 Property and equipment, net 2,950 Operating right-of-use asset 23,545 Intangible assets (1) 244,500 Other assets 370 Goodwill 600,070 Accounts payable and other liabilities (20,239) Deferred revenue (4,526) Operating lease liability, noncurrent (23,169) Deferred tax liability (18,144) Total purchase price $ 838,448 ____________________________________ ( 1 ) Identifiable intangible assets are comprised of the following: Total Estimated (In thousands) (In years) Developed technology $ 56,800 7 Customer relationships 147,700 10 Supplier relationships 39,600 5 Trade names 400 5 Total intangible assets acquired $ 244,500 The Company acquired a net deferred tax liability of $18.1 million in this business combination that is included in long-term liabilities in the accompanying consolidated balance sheet. Goodwill generated from this acquisition primarily represents the value that is expected from the increased scale and synergies as a result of the integration of both businesses. Goodwill is not deductible for tax purposes. The estimated fair value of the intangible assets acquired was determined by the Company. The Company engaged a third‑party expert to assist with the valuation analysis. The Company used a relief-from-royalty method to estimate the fair values of the developed technology and trade names, a multi-period excess earnings method to estimate the fair values of customer relationships and a with-and-without method to estimate the fair value of the supplier relationships. Most of the net tangible assets were valued at their respective carrying amounts as of the acquisition date, as the Company believes that these amounts approximate their current fair values, except for operating right-of-use assets. The value of the acquired operating right-of-use assets was reduced by $1.7 million to its respective fair value on the acquisition date. The acquired entity's results of operations were included in the Company's consolidated financial statements from the date of acquisition, July 14, 2021. For the three months ended September 30, 2021, Zipwhip contributed net operating revenue of $23.6 million, which is reflected in the accompanying consolidated statement of operations. Due to the integrated nature of the Company's operations, the Company believes that it is not practicable to separately identify earnings of Zipwhip on a stand-alone basis. Pro forma results of operations for this acquisition are not presented as the financial impact to the Company's consolidated financial statements is not material. During the three and nine months ended September 30, 2021, the Company incurred costs related to this acquisition of $1.6 million and $4.2 million, respectively, that were expensed as incurred and recorded in general and administrative expenses in the accompanying consolidated statement of operations.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The Goodwill balance as of September 30, 2021 and December 31, 2020, was as follows: Total (In thousands) Balance as of December 31, 2020 $ 4,595,394 Goodwill additions and adjustments 667,657 Balance as of September 30, 2021 $ 5,263,051 Intangible assets Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 794,831 $ (194,285) $ 600,546 Customer relationships 538,264 (108,953) 429,311 Supplier relationships 51,671 (6,916) 44,755 Trade names 30,669 (12,327) 18,342 Order backlog 10,000 (9,167) 833 Patent 4,071 (474) 3,597 Total amortizable intangible assets 1,429,506 (332,122) 1,097,384 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,434,721 $ (332,122) $ 1,102,599 As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 724,599 $ (113,282) $ 611,317 Customer relationships 379,344 (59,574) 319,770 Supplier relationships 4,356 (3,044) 1,312 Trade name 25,560 (7,921) 17,639 Order backlog 10,000 (1,667) 8,333 Patent 3,360 (373) 2,987 Total amortizable intangible assets 1,147,219 (185,861) 961,358 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,152,434 $ (185,861) $ 966,573 Amortization expense was $55.7 million and $146.3 million for the three and nine months ended September 30, 2021, respectively, and $20.4 million and $61.3 million for the three and nine months ended September 30, 2020, respectively. Total estimated future amortization expense is as follows: As of Year Ended December 31, (In thousands) 2021 (remaining three months) $ 52,554 2022 204,832 2023 201,522 2024 195,948 2025 192,374 Thereafter 250,154 Total $ 1,097,384

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	9 Months Ended
	Sep. 30, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other current liabilities consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 66,094 $ 54,683 Accrued bonus and commission 36,155 25,341 Accrued cost of revenue 115,996 80,620 Sales and other taxes payable 63,660 48,390 ESPP contributions 19,354 6,272 Finance lease liability, current 10,150 9,062 Accrued other expense 57,274 28,527 Total accrued expenses and other current liabilities $ 368,683 $ 252,895 Other long-term liabilities consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Deferred tax liability $ 20,446 $ 13,684 Acquisition holdback 8,502 8,800 Accrued other expenses 20,243 14,149 Total other long-term liabilities $ 49,191 $ 36,633

Notes Payable

Notes Payable	9 Months Ended
	Sep. 30, 2021
Long-term Debt, Unclassified [Abstract]
Notes Payable	Notes Payable Long-term debt consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) 2029 and 2031 Senior Notes 2029 Senior Notes Principal $ 500,000 $ — Unamortized discount (5,872) — Unamortized issuance costs (1,316) — Net carrying amount 492,812 — 2031 Senior Notes Principal 500,000 — Unamortized discount (5,962) — Unamortized issuance costs (1,303) — Net carrying amount 492,735 — Convertible Senior Notes and Capped Call Transactions Convertible Senior Notes Principal — 343,702 Unamortized discount — (38,406) Unamortized issuance costs — (3,228) Net carrying amount — 302,068 Total long-term debt $ 985,547 $ 302,068 2029 and 2031 Senior Notes In March 2021, the Company issued $1.0 billion aggregate principal amount of senior notes, consisting of $500.0 million principal amount of 3.625% notes due 2029 (the “2029 Notes”) and $500.0 million principal amount of 3.875% notes due 2031 (the “2031 Notes,” and together with the 2029 Notes, the “Notes”). Initially, none of the Company’s subsidiaries guaranteed the Notes. However, under certain circumstances in the future the Notes may be guaranteed by each of the Company’s material domestic subsidiaries. The 2029 Notes and 2031 Notes will mature on March 15, 2029 and March 15, 2031, respectively. Interest payments are payable semi-annually in arrears on March 15 and September 15 of each year, commencing on September 15, 2021. The aggregate net proceeds from offering of the Notes were approximately $985.1 million, after deducting underwriting discounts and issuance costs, paid and payable by the Company. The issuance costs of $2.4 million will be amortized into interest expense using the effective interest method over the term of the Notes. The Company may voluntarily redeem the 2029 Notes, in whole or in part, under the following circumstances: (1) at any time prior to March 15, 2024 with the net cash proceeds received by the Company from an equity offering at a redemption price equal to 103.625% of the principal amount, provided the aggregate principal amount of all such redemptions does not exceed 40% of the original aggregate principal amount of the 2029 Notes. Such redemption shall occur within 180 days after the closing of an equity offering and at least 50% of the then-outstanding aggregate principal amount of the 2029 Notes shall remain outstanding, unless all 2029 Notes are redeemed concurrently; (2) at any time prior to March 15, 2024 at 100% of the principal amount, plus a “make-whole” premium; (3) at any time on or after March 15, 2024 at a prepayment price equal to 101.813% of the principal amount; (4) at any time on or after March 15, 2025 at a prepayment price equal to 100.906% of the principal amount; and (5) at any time on or after March 15, 2026 at a prepayment price equal to 100.000% of the principal amount; in each case, the redemption will include the accrued and unpaid interest, as applicable. The Company may voluntarily redeem the 2031 Notes, in whole or in part, under the following circumstances: (1) at any time prior to March 15, 2024 with the net cash proceeds received by the Company from an equity offering at a redemption price equal to 103.875% of the principal amount, provided the aggregate principal amount of all such redemptions does not to exceed 40% of the original aggregate principal amount of the 2031 Notes. Such redemption shall occur within 180 days after the closing of an equity offering and at least 50% of the then-outstanding aggregate principal amount of the 2031 Notes shall remain outstanding, unless all 2031 Notes are redeemed concurrently; (2) at any time prior to March 15, 2026 at 100% of the principal amount, plus a “make-whole” premium; (3) at any time on or after March 15, 2026 at a prepayment price equal to 101.938% of the principal amount; (4) at any time on or after March 15, 2027 at a prepayment price equal to 101.292% of the principal amount; (5) at any time on or after March 15, 2028 at a prepayment price equal to 100.646% of the principal amount; and (6) at any time on or after March 15, 2029 at a prepayment price equal to 100.000% of the principal amount; in each case, the redemption will include accrued and unpaid interest, as applicable. The Notes are unsecured obligations and will rank senior in right of payment to any of the Company’s indebtedness that is expressly subordinated in right of payment to the Notes that the Company may incur in the future and equal in right of payment with the Company’s existing and future liabilities that are not subordinated. In certain circumstances involving a change of control event, the Company will be required to make an offer to repurchase all, or, at the holder’s option, any part, of each holder’s notes of that series at 101% of the aggregate principal amount, plus accrued and unpaid interest, as applicable. The indenture governing the Notes (the “Indenture”) contains covenants limiting the Company’s ability and the ability of its subsidiaries to: (i) create liens on certain assets to secure debt; (ii) grant a subsidiary guarantee of certain debt without also providing a guarantee of the Notes; and (iii) consolidate or merge with or into, or sell or otherwise dispose of all or substantially all of its assets to another person. These covenants are subject to a number of limitations and exceptions. Certain of these covenants will not apply during any period in which the Notes are rated investment grade by either Moody’s Investors Service, Inc. or Standard & Poor’s Ratings Services. For the three and nine months ended September 30, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: Three Months Ended Nine Months Ended 2021 2021 (In thousands) 2029 Notes Contractual interest expense $ 4,531 $ 10,182 Amortization of debt discount and issuance costs 246 463 Total interest expense - 2029 Notes 4,777 10,645 2031 Notes Contractual interest expense 4,844 10,885 Amortization of debt discount and issuance costs 188 352 Total interest expense - 2031 Notes 5,032 11,237 Total interest expense $ 9,809 $ 21,882 As of September 30, 2021, the Company was in compliance with all of its financial covenants under the Indenture. Convertible Senior Notes and Capped Call Transactions During the second quarter of 2021, the Company redeemed its Convertible Notes in their entirety and settled the related capped call transactions. As of June 30, 2021, the Convertible Notes were no longer outstanding.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information A roll‑forward of the Company’s reserves is as follows: (a) Allowance for doubtful accounts: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 15,413 $ 10,248 $ 12,046 $ 6,287 Additions 4,122 1,312 13,490 8,472 Write-offs (2,703) (832) (8,704) (4,031) Balance, end of period $ 16,832 $ 10,728 $ 16,832 $ 10,728 (b) Customer credit reserve: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 16,167 $ 11,531 $ 16,783 $ 6,784 Additions 14,211 12,164 41,596 33,714 Deductions against reserve (12,716) (12,915) (40,717) (29,718) Balance, end of period $ 17,662 $ 10,780 $ 17,662 $ 10,780

Revenue by Geographic Area

Revenue by Geographic Area	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue by Geographic Area	Revenue by Geographic Area Revenue by geographic area is based on the IP address or the mailing address of the customer at the time of registration. The following table sets forth revenue by geographic area: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Revenue by geographic area: (In thousands) United States $ 497,993 $ 328,056 $ 1,372,436 $ 881,984 International 242,183 119,913 626,659 331,702 Total $ 740,176 $ 447,969 $ 1,999,095 $ 1,213,686 Percentage of revenue by geographic area: United States 67 % 73 % 69 % 73 % International 33 % 27 % 31 % 27 % Long-lived assets outside of the United States were not significant.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease and Other Commitments The Company has entered into various non-cancelable operating lease agreements for its facilities with remaining lease terms ranging from less than one year to approximately eight years. See Note 6 to these condensed consolidated financial statements for additional detail on the Company’s operating and finance lease commitments. Additionally, the Company has non-cancelable contractual commitments with its cloud infrastructure provider, network service providers and other vendors. In the three and nine months ended September 30, 2021, the Company entered into several such agreements with terms up to four years for a total purchase commitment of $9.0 million and $447.0 million, respectively. In February 2021, the Company entered into a Framework Agreement with Syniverse Corporation (“Syniverse”) and Carlyle Partners V Holdings, L.P. (“Carlyle”) (the “Framework Agreement”), pursuant to which Syniverse will issue to the Company shares of Syniverse common stock in consideration for an investment by the Company of up to $750.0 million. In August 2021, Syniverse entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Blue Steel Merger Sub Inc. and M-3 Brigade Acquisition II Corp. (“MBAC”), which will result in Syniverse being a wholly owned subsidiary of MBAC (the “Merger”). Concurrently, the Company and MBAC entered into the Twilio Subscription Agreement (the “Subscription Agreement”), pursuant to which the Company has agreed, subject to the terms and conditions set forth therein, to subscribe for and purchase, and MBAC agreed to issue and sell to the Company, immediately prior to the closing of the Merger, shares of Class A common stock and, if applicable, shares of Class C common stock for an aggregate amount between $500.0 million and $750.0 million, depending on redemptions by MBAC’s shareholders. The Company and Syniverse also entered into an amendment to the Framework Agreement to conform the Framework Agreement to the Merger and the terms of the Merger Agreement. In connection with the closing of the investment, the Company and Syniverse will enter into a wholesale agreement, in which Syniverse will process, route and deliver application-to-person messages originating and/or terminating between the Company’s customers and mobile network operators. The investment is expected to result in the Company holding a significant minority equity ownership position in Syniverse, subject to certain adjustments based on the terms of the final agreement. This proposed transaction closing is subject to consummation of certain other transactions by Syniverse, as defined in the Framework Agreement, and other customary closing conditions, including regulatory approvals. The closing is expected to occur before the end of 2021. As of September 30, 2021, the Company has deferred $4.8 million of costs related to this proposed transaction that are recorded in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheet. The City and County of San Francisco (“San Francisco”) has assessed the Company for additional Telephone Users Tax (“TUT”) and Access Line Tax (“ALT”) on certain of the Company’s services for the years 2009 through 2018. The assessments totaled $38.8 million, including interest and penalties. The Company paid the assessments under protest in the third quarter of 2020. On May 27, 2021, the Company filed a lawsuit against San Francisco in San Francisco Superior Court challenging the assessments. The Company raised numerous defenses to the assessments including that its services are not telecommunications services, application of the taxes to Twilio’s services violates the Internet Tax Freedom Act and San Francisco does not have jurisdiction to impose tax on services provided outside of San Francisco. The Company is seeking refunds of the taxes paid, waivers of interest and penalties, cost of suit and reasonable attorneys’ fees, and other legal and equitable relief as the court deems appropriate. The Company believes it has strong arguments that TUT and ALT do not apply to its services, but litigation is uncertain and there is no assurance that it will prevail in court. Should the Company lose on one or more of its arguments, it could incur additional losses associated with taxes, interest, and penalties that together, in aggregate, could be material. The Company regularly assesses the likelihood of adverse outcomes resulting from tax disputes such as this and examines all open years to determine the necessity and adequacy of any tax reserves. The Company’s tax reserves are further discussed in Note 13 (d) of these condensed consolidated financial statements. In addition to the litigation discussed above, from time to time, the Company may be subject to legal actions and claims in the ordinary course of business. The Company has received, and may in the future continue to receive, claims from third parties asserting, among other things, infringement of their intellectual property rights. Future litigation may be necessary to defend the Company, its partners and its customers by determining the scope, enforceability and validity of third‑party proprietary rights, or to establish our proprietary rights. The results of any current or future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors. Legal fees and other costs related to litigation and other legal proceedings are expensed as incurred and are included in general and administrative expenses in the accompanying condensed consolidated statements of operations. The Company has signed indemnification agreements with all of its board members and executive officers. The agreements indemnify the board members and executive officers from claims and expenses of actions brought against the individuals separately or jointly with the Company for certain indemnifiable events. Indemnifiable events generally mean any event or occurrence related to the fact that the board member or the executive officer was or is acting in his or her capacity as a board member or an executive officer for the Company or was or is acting or representing the interests of the Company. In the ordinary course of business and in connection with our financing and business combinations transactions, the Company enters into contractual arrangements under which it agrees to provide indemnification of varying scope and terms to business partners, customers 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 the Company’s various products, or its 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, the Company’s obligations under these agreements may be limited in terms of time and/or amount, and in some instances, the Company may have recourse against third parties for certain payments. The terms of such obligations may vary. As of September 30, 2021 and December 31, 2020, no amounts were accrued related to any outstanding indemnification agreements. The Company conducts operations in many tax jurisdictions within and outside the United States. In many of these jurisdictions, non-income-based taxes, such as sales, use, telecommunications, and other local taxes are assessed on the Company’s operations. Prior to March 2017, the Company had not billed nor collected these taxes from its customers and, in accordance with U.S. GAAP, recorded a provision for its tax exposure in these jurisdictions when it was both probable that a liability had been incurred and the amount of the exposure could be reasonably estimated. These estimates included several key assumptions including, but not limited to, the taxability of the Company’s services, the jurisdictions in which its management believes it had nexus, and the sourcing of revenues to those jurisdictions. Starting in March 2017, the Company began collecting these taxes from customers in certain jurisdictions and since then has expanded to collect taxes in most jurisdictions where the Company operates. The Company is also in discussions with certain jurisdictions regarding its prior sales and other taxes, if any, that it may owe. In the event any of these jurisdictions disagree with management’s assumptions and analysis, the assessment of the Company’s tax exposure could differ materially from management’s current estimates. For example, San Francisco City and County has assessed the Company for $38.8 million in taxes, including interest and penalties, which exceeded the $11.5 million the Company had accrued for the period covered by this assessment. The Company paid the full amount as required by law. The payment made in excess of the accrued amount is reflected as a deposit in the accompanying condensed consolidated balance sheets. The Company believes, however, that this assessment is incorrect and, after failing to reach a settlement, filed a lawsuit on May 27, 2021 contesting the assessment. However, litigation is uncertain and a ruling against the Company, or a dismissal of our complaint, may adversely affect its financial position and results of operations. As of September 30, 2021, the liabilities recorded for these taxes were $27.9 million for domestic jurisdictions and $15.3 million for jurisdictions outside of the United States. As of December 31, 2020, these liabilities were $25.6 million and $9.6 million, respectively.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock As of September 30, 2021 and December 31, 2020, the Company had authorized 100,000,000 shares of preferred stock, par value $0.001, of which no shares were issued and outstanding. Common Stock As of September 30, 2021 and December 31, 2020, the Company had authorized 1,000,000,000 shares of Class A common stock and 100,000,000 shares of Class B common stock, each par value $0.001 per share. As of September 30, 2021, 168,352,933 shares of Class A common stock and 9,913,181 shares of Class B common stock were issued and outstanding. As of December 31, 2020, 153,496,222 shares of Class A common stock and 10,551,302 shares of Class B common stock were issued and outstanding. Holders of Class A and Class B common stock are entitled to one vote per share and 10 votes per share, respectively, and the shares of Class A common stock and Class B common stock are identical, except for voting and conversion rights. The Company has reserved shares of common stock for issuance as follows: As of As of September 30, December 31, 2021 2020 Stock options issued and outstanding 4,510,986 5,625,735 Unvested restricted stock units issued and outstanding 6,467,518 7,523,882 Class A common stock reserved for Twilio.org 640,959 707,265 Stock-based awards available for grant under 2016 Plan 25,591,744 18,942,205 Stock-based awards available for grant under ESPP 6,481,649 4,941,281 Class A common stock reserved for the Convertible Notes — 7,569,731 Total 43,692,856 45,310,099

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company’s 2016 Stock Option and Incentive Plan (the “2016 Plan”) provides for granting stock options, restricted stock units (“RSU”), restricted stock awards (“RSA”), stock appreciation rights, unrestricted stock awards, performance share awards, dividend equivalent rights and cash-based awards to its employees, directors and consultants. Certain of the Company’s outstanding equity awards were granted under equity incentive plans that are no longer active but continue to govern the outstanding equity awards granted thereunder. The Company also offers an Employee Stock Purchase Plan (“ESPP”) to eligible employees. The ESPP provides for separate six-month offering periods beginning in May and November of each year. In the three months ended September 30, 2021 and 2020, no shares of Class A common stock were purchased under the ESPP and 107,815 shares are expected to be purchased in the fourth quarter of 2021. On January 1, 2021, the shares available for grant under the 2016 Plan and ESPP were automatically increased by 8,202,376 shares and 1,640,475 shares, respectively. Stock-options and restricted stock units and awards activity under the Company’s equity incentive plans was as follows: Stock Options Number of Weighted- Weighted- Aggregate Outstanding options as of December 31, 2020 5,070,735 $ 51.71 6.85 $ 1,454,222 Granted 249,842 368.82 Assumed in acquisition 83,539 49.26 Exercised (1,122,523) 42.76 Forfeited and canceled (325,607) 120.73 Outstanding options as of September 30, 2021 3,955,986 $ 68.53 6.21 $ 1,002,796 Options vested and exercisable as of September 30, 2021 2,482,865 $ 28.83 5.03 $ 721,478 Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 93,920 $ 89,808 $ 359,904 $ 496,198 Total estimated grant date fair value of options vested $ 27,629 $ 12,090 $ 105,481 $ 53,110 Weighted-average grant date fair value per share of options granted or assumed in acquisition $ 331.57 $ — $ 234.74 $ 64.06 ____________________________________ ( 1 ) Aggregate intrinsic value represents the difference between the fair value of the Company’s Class A common stock as reported on the New York Stock Exchange and the exercise price of outstanding “in-the-money” options. Additionally, as of September 30, 2021, the Company had outstanding 555,000 shares of performance-based stock options with a weighted average exercise price of $31.72, of which 555,000 were vested and exercisable. All performance conditions have been met. Restricted Stock Units and Awards Number of Weighted- Aggregate Unvested RSUs as of December 31, 2020 7,523,882 $ 131.76 $ 2,542,858 Granted 2,220,043 345.57 Vested (2,570,006) 101.86 Forfeited and canceled (706,401) 170.27 Unvested RSUs as of September 30, 2021 6,467,518 $ 212.83 $ 2,063,462 Additionally, as of September 30, 2021, the Company granted 24,697 shares of RSAs with a weighted average grant date fair value of $359.80 per share and aggregate intrinsic value of $7.8 million. As of September 30, 2021, the Company had 318,087 shares of its Class A common stock in escrow that are subject to future vesting over a period of 2.2 years with a weighted average grant date fair value of $292.46 per share and aggregate intrinsic value of $101.5 million. As of September 30, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 189,118 2.1 Unvested restricted stock units and awards 1,235,756 3.0 Class A shares in escrow subject to future vesting 67,821 2.2 ESPP 2,360 0.1 Total $ 1,495,055 Valuation Assumptions No stock options were granted in the three months ended September 30, 2020. The fair value of employee stock options was estimated on the grant date using the following assumptions in the Black-Scholes option pricing model: Three Months Ended Nine Months Ended Employee Stock Options: 2021 2020 2021 2020 Fair value of common stock $342.0 - $375.4 $— $316.31 - $409.21 $108.4 - $191.9 Expected term (in years) 0.30 - 5.40 — 0.30 - 6.08 6.08 Expected volatility 42.9% - 61.5% —% 42.9% - 61.5% 51.9% - 56.0% Risk-free interest rate 0.1% - 0.9% —% 0.1% - 1.1% 0.4% - 1.4% Dividend rate —% —% —% —% Nine Months Ended Employee Stock Purchase Plan: 2021 2020 Expected term (in years) 0.5 0.5 Expected volatility 58.7% 72.1% Risk-free interest rate 0.04% 0.2% Dividend rate —% —% Stock-Based Compensation Expense The Company recorded total stock-based compensation expense as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Cost of revenue $ 3,720 $ 2,237 $ 9,461 $ 6,217 Research and development 69,242 46,294 185,072 119,344 Sales and marketing 53,843 26,573 143,419 69,602 General and administrative 37,238 14,306 107,414 42,659 Total $ 164,043 $ 89,410 $ 445,366 $ 237,822

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common StockholdersBasic and diluted net loss per common share is presented in conformity with the two-class method required for participating securities and is described in detail in the Company’s Annual Report. The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Net loss attributable to common stockholders (in thousands) $ (224,109) $ (116,914) $ (658,504) $ (311,628) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 177,231,285 147,501,075 172,605,371 142,832,021 Net loss per share attributable to common stockholders, basic and diluted $ (1.26) $ (0.79) $ (3.82) $ (2.18) The following outstanding shares of common stock equivalents were excluded from the calculation of the diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive: As of September 30, 2021 2020 Stock options issued and outstanding 4,510,986 4,946,920 Restricted stock units issued and outstanding 6,467,518 8,026,189 Class A common stock reserved for Twilio.org 640,959 729,367 Class A common stock committed under ESPP 107,815 103,374 Convertible senior notes (1) — 5,013,815 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future vesting 342,784 — Total 12,145,674 18,819,665 ____________________________________ (1) During the second quarter of 2021, the remaining principal amount of the Convertible Notes was fully redeemed and as of June 30, 2021, no Convertible Notes were outstanding. As of September 30, 2020, the Company was using treasury stock method to calculate the dilutive impact of the Convertible Notes because at that time the Company expected to settle the principal amount of these notes in cash and any excess in shares of the Company’s Class A common stock. Effective with the fourth quarter 2020, the Company expected to settle the principal amount of these notes in shares of the Company’s Class A common stock, and since then used the if-converted method for calculating a potential dilutive effect on diluted net income per share, if applicable. As of September 30, 2020, the conversion spread, calculated using the average market price of Class A common stock during the period consistent with the treasury stock method, had a dilutive impact on diluted net income per share of Class A common stock when the average market price of the Company’s Class A common stock for a given period exceeded the conversion price of $70.90 per share.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company computes its provision for interim periods by applying an estimated annual effective tax rate to anticipated annual pretax income or loss. The estimated annual effective tax rate is applied to the Company’s year to date income or loss, and is adjusted for discrete items recorded in the period. The Company recorded an income tax benefit of $14.8 million and $12.7 million for the three and nine months ended September 30, 2021, respectively, and an income tax provision of $0.6 million and $1.9 million for the three and nine months ended September 30, 2020, respectively. The benefit for income taxes recorded in the three and nine months ended September 30, 2021 consists primarily of the income tax benefit from the reversal of U.S. valuation allowance related to acquired intangibles from current year business combinations partially offset with income taxes and withholding taxes in foreign jurisdictions in which the Company conducts business. The provision for income taxes recorded in the three and nine months ended September 30, 2020 consists primarily of income taxes and withholding taxes in foreign jurisdictions in which the Company conducts business.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on February 26, 2021 (“Annual Report”). The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but may not include all disclosures including certain notes required by U.S. GAAP on an annual reporting basis. In the opinion of management, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the 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 2021 or any future period.
Principles of Consolidation	Principles of ConsolidationThe condensed consolidated financial statements include the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated.
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates are used for, but not limited to, allowances for doubtful accounts and customer credit reserves; recoverability of long-lived and intangible assets; capitalization and useful life of the Company’s capitalized internal-use software development costs; fair value of acquired intangible assets and goodwill; accruals and contingencies. Estimates are based on historical experience and on various assumptions that the Company believes are reasonable under current circumstances. However, future events are subject to change and best estimates and judgments may require further adjustments; therefore, actual results could differ materially from those estimates. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation.
Concentration of Credit Risk	Concentration of Credit RiskFinancial instruments that potentially expose the Company to a concentration of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains cash, cash equivalents and marketable securities with financial institutions that management believes are financially sound and have minimal credit risk exposure although the balances will exceed insured limits.The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customer deteriorates substantially, the Company’s results of operations could be adversely affected. To reduce credit risk, management performs credit evaluations of the financial condition of significant customers. The Company does not require collateral from its credit customers and maintains reserves for estimated credit losses on customer accounts when considered necessary. Actual credit losses may differ from the Company’s estimates.
Changes to Significant Accounting Policies	Changes to Significant Accounting Policies Derivatives and Hedging The Company is exposed to a wide variety of risks arising from its business operations and overall economic conditions. These risks include exposure to fluctuations in various foreign currencies against its functional currency and can impact the value of cash receipts and payments. The Company minimizes its exposure to these risks through management of its core business activities, specifically, the amounts, sources and duration of its assets and liabilities, and the use of derivative financial instruments. In the second quarter of 2021, the Company started using foreign currency derivative forward contracts and in the future may also use foreign currency option contacts. Foreign currency derivative forward contracts involve fixing the exchange rate for delivery of a specified amount of foreign currency on a specified date. These agreements are typically cash settled in U.S. dollars for their fair value at or close to their settlement date. Foreign currency option contracts will require the Company to pay a premium for the right to sell a specified amount of foreign currency prior to the maturity date of the option. The Company does not enter into derivative financial instruments trading for speculative purposes. Derivative instruments are carried at fair value and recorded as either an asset or a liability until they mature. Gains and losses resulting from changes in fair value of these instruments are accounted for depending on the use of the derivative and whether it is designated and qualifies for hedge accounting. For derivative instruments designated as cash flow hedges, gains or losses are initially recorded in other comprehensive income (“OCI”) in the balance sheet, then reclassified into the statement of operations in the period in which the derivative instrument matures. These realized gains and losses are recorded within the same financial statement line item as the hedged transaction. The Company’s foreign currency derivative contracts are classified within Level 2 of the fair value hierarchy because the valuation inputs are based on quoted prices and market observable data of similar instruments in active markets, such as currency spot and forward rates. There have been no other changes to the Company’s significant accounting policies as described in its Annual Report.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of financial assets measured at fair value on a recurring basis	The following tables provide the financial assets and liabilities measured at fair value on a recurring basis: Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 1,087,268 $ — $ — $ 1,087,268 $ — $ — $ 1,087,268 Commercial paper 74,209 — — — 74,209 — 74,209 Total included in cash and cash equivalents 1,161,477 — — 1,087,268 74,209 — 1,161,477 Marketable securities: U.S. Treasury securities 349,951 73 (353) 349,671 — — 349,671 Non-U.S. Government securities 242,258 4 (249) 242,013 — — 242,013 Corporate debt securities and commercial paper 3,302,309 4,141 (1,380) 27,000 3,278,070 — 3,305,070 Total marketable securities 3,894,518 4,218 (1,982) 618,684 3,278,070 — 3,896,754 Total financial assets $ 5,055,995 $ 4,218 $ (1,982) $ 1,705,952 $ 3,352,279 $ — $ 5,058,231 Financial Liabilities: Accrued expenses and other current liabilities: Foreign currency derivative liabilities $ — $ — $ (3,069) $ — $ (3,069) $ — $ (3,069) Total financial liabilities $ — $ — $ (3,069) $ — $ (3,069) $ — $ (3,069) Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 656,749 $ — $ — $ 656,749 $ — $ — $ 656,749 Commercial paper 2,000 — — — 2,000 — 2,000 Total included in cash and cash equivalents 658,749 — — 656,749 2,000 — 658,749 Marketable securities: U.S. Treasury securities 223,247 389 (1) 223,635 — — 223,635 Corporate debt securities and commercial paper 1,874,257 8,149 (135) 50,000 1,832,271 — 1,882,271 Total marketable securities 2,097,504 8,538 (136) 273,635 1,832,271 — 2,105,906 Total financial assets $ 2,756,253 $ 8,538 $ (136) $ 930,384 $ 1,834,271 $ — $ 2,764,655
Schedule of contractual maturities of marketable securities	The following table summarizes the contractual maturities of marketable securities: As of September 30, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,119,954 $ 1,121,537 $ 1,126,091 $ 1,128,927 One to three years 2,774,564 2,775,217 971,413 976,979 Total $ 3,894,518 $ 3,896,754 $ 2,097,504 $ 2,105,906

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Gain (Loss)	Losses associated with these foreign currency forward contracts were as follows: Condensed Consolidated Statement of Operations and Statement of Comprehensive Loss Three Months Ended Nine Months Ended 2021 2021 (In thousands) Losses recognized in OCI Net change in market value of effective foreign currency forward exchange contracts $ (161) $ (3,069) Losses recognized in income due to instruments maturing Cost of revenue $ (2,464) $ (2,931)

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 185,037 $ 142,489 Data center equipment (1) 64,104 43,477 Leasehold improvements 80,897 69,756 Office equipment 56,291 35,346 Furniture and fixtures (1) 15,646 12,312 Software 10,491 9,943 Total property and equipment 412,466 313,323 Less: accumulated depreciation and amortization (175,225) (130,084) Total property and equipment, net $ 237,241 $ 183,239 ____________________________________ ( 1 ) Data center equipment and furniture and fixtures contain assets under finance leases. See Note 6 for further detail. Supplemental depreciation and amortization disclosures are as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Depreciation and amortization expense $ 14,546 $ 12,843 $ 43,198 $ 36,674 Capitalized internal-use software development costs $ 17,999 $ 12,172 $ 49,527 $ 36,738 Stock based compensation costs included in capitalized internal-use software development costs $ 5,198 $ 3,696 $ 14,938 $ 10,711 Amortization of capitalized internal-use software development costs $ 4,419 $ 4,380 $ 13,270 $ 13,389

Right-of-Use Asset and Lease _2

Right-of-Use Asset and Lease Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Lease, Cost	The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 16,141 $ 12,127 $ 45,519 $ 35,048 Finance lease cost: Amortization of assets 2,905 2,384 8,389 6,118 Interest on lease liabilities 282 212 805 604 Short-term lease cost 802 1,195 3,340 3,698 Variable lease cost 2,389 2,066 7,322 5,246 Total net lease cost $ 22,519 $ 17,984 $ 65,375 $ 50,714 Supplemental cash flow and other information related to leases was as follows: Nine Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 44,551 $ 34,124 Operating cash flows from finance leases (interest) $ 788 $ 604 Financing cash flows from finance leases $ 8,343 $ 5,721 Weighted average remaining lease term (in years): Operating leases 5.7 5.6 Finance leases 3.1 3.4 Weighted average discount rate: Operating leases 4.5 % 5.3 % Finance leases 3.5 % 4.1 %
Assets and Liabilities, Lessee	Supplemental balance sheet information related to leases was as follows: As of As of September 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 248,582 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 29,027 25,771 Total leased assets $ 277,609 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 50,760 $ 48,338 Finance Finance lease liability, current 10,150 9,062 Noncurrent Operating Operating lease liability, noncurrent 223,033 229,905 Finance Finance lease liability, noncurrent 20,254 17,856 Total lease liabilities $ 304,197 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $88.9 million and $57.1 million as of September 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $23.4 million and $15.0 million as of September 30, 2021 and December 31, 2020, respectively.
Lessee, Operating Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of September 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining three months) $ 14,742 $ 2,920 2022 63,245 10,681 2023 55,476 9,934 2024 50,857 6,693 2025 37,706 1,394 Thereafter 89,223 518 Total lease payments 311,249 32,140 Less: imputed interest (37,456) (1,736) Total lease obligations 273,793 30,404 Less: current obligations (50,760) (10,150) Long-term lease obligations $ 223,033 $ 20,254
Finance Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of September 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining three months) $ 14,742 $ 2,920 2022 63,245 10,681 2023 55,476 9,934 2024 50,857 6,693 2025 37,706 1,394 Thereafter 89,223 518 Total lease payments 311,249 32,140 Less: imputed interest (37,456) (1,736) Total lease obligations 273,793 30,404 Less: current obligations (50,760) (10,150) Long-term lease obligations $ 223,033 $ 20,254

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Purchase price components	The purchase price components are summarized in the following table: Total (In thousands) Fair value of Class A common stock transferred $ 419,037 Cash consideration 417,900 Fair value of the pre-combination service through equity awards 1,511 Total purchase price $ 838,448
Schedule of purchase price allocation	The following table presents the preliminary purchase price allocation recorded in the Company's consolidated balance sheet as of September 30, 2021: Total (In thousands) Cash and cash equivalents $ 21,610 Accounts receivable and other current assets 11,481 Property and equipment, net 2,950 Operating right-of-use asset 23,545 Intangible assets (1) 244,500 Other assets 370 Goodwill 600,070 Accounts payable and other liabilities (20,239) Deferred revenue (4,526) Operating lease liability, noncurrent (23,169) Deferred tax liability (18,144) Total purchase price $ 838,448 ____________________________________ ( 1 ) Identifiable intangible assets are comprised of the following: Total Estimated (In thousands) (In years) Developed technology $ 56,800 7 Customer relationships 147,700 10 Supplier relationships 39,600 5 Trade names 400 5 Total intangible assets acquired $ 244,500

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill balance	The Goodwill balance as of September 30, 2021 and December 31, 2020, was as follows: Total (In thousands) Balance as of December 31, 2020 $ 4,595,394 Goodwill additions and adjustments 667,657 Balance as of September 30, 2021 $ 5,263,051
Schedule of intangible assets	Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 794,831 $ (194,285) $ 600,546 Customer relationships 538,264 (108,953) 429,311 Supplier relationships 51,671 (6,916) 44,755 Trade names 30,669 (12,327) 18,342 Order backlog 10,000 (9,167) 833 Patent 4,071 (474) 3,597 Total amortizable intangible assets 1,429,506 (332,122) 1,097,384 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,434,721 $ (332,122) $ 1,102,599 As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 724,599 $ (113,282) $ 611,317 Customer relationships 379,344 (59,574) 319,770 Supplier relationships 4,356 (3,044) 1,312 Trade name 25,560 (7,921) 17,639 Order backlog 10,000 (1,667) 8,333 Patent 3,360 (373) 2,987 Total amortizable intangible assets 1,147,219 (185,861) 961,358 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,152,434 $ (185,861) $ 966,573
Schedule of total estimated future amortization expense	Total estimated future amortization expense is as follows: As of Year Ended December 31, (In thousands) 2021 (remaining three months) $ 52,554 2022 204,832 2023 201,522 2024 195,948 2025 192,374 Thereafter 250,154 Total $ 1,097,384

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 66,094 $ 54,683 Accrued bonus and commission 36,155 25,341 Accrued cost of revenue 115,996 80,620 Sales and other taxes payable 63,660 48,390 ESPP contributions 19,354 6,272 Finance lease liability, current 10,150 9,062 Accrued other expense 57,274 28,527 Total accrued expenses and other current liabilities $ 368,683 $ 252,895
Schedule of other long-term liabilities	Other long-term liabilities consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) Deferred tax liability $ 20,446 $ 13,684 Acquisition holdback 8,502 8,800 Accrued other expenses 20,243 14,149 Total other long-term liabilities $ 49,191 $ 36,633

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
	Sep. 30, 2021
Long-term Debt, Unclassified [Abstract]
Schedule of net carrying amount of the liability and equity components of the Notes	Long-term debt consisted of the following: As of As of September 30, December 31, 2021 2020 (In thousands) 2029 and 2031 Senior Notes 2029 Senior Notes Principal $ 500,000 $ — Unamortized discount (5,872) — Unamortized issuance costs (1,316) — Net carrying amount 492,812 — 2031 Senior Notes Principal 500,000 — Unamortized discount (5,962) — Unamortized issuance costs (1,303) — Net carrying amount 492,735 — Convertible Senior Notes and Capped Call Transactions Convertible Senior Notes Principal — 343,702 Unamortized discount — (38,406) Unamortized issuance costs — (3,228) Net carrying amount — 302,068 Total long-term debt $ 985,547 $ 302,068
Schedule of interest expense recognized related to the Notes	For the three and nine months ended September 30, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: Three Months Ended Nine Months Ended 2021 2021 (In thousands) 2029 Notes Contractual interest expense $ 4,531 $ 10,182 Amortization of debt discount and issuance costs 246 463 Total interest expense - 2029 Notes 4,777 10,645 2031 Notes Contractual interest expense 4,844 10,885 Amortization of debt discount and issuance costs 188 352 Total interest expense - 2031 Notes 5,032 11,237 Total interest expense $ 9,809 $ 21,882

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Schedule of the allowance for doubtful accounts	Allowance for doubtful accounts: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 15,413 $ 10,248 $ 12,046 $ 6,287 Additions 4,122 1,312 13,490 8,472 Write-offs (2,703) (832) (8,704) (4,031) Balance, end of period $ 16,832 $ 10,728 $ 16,832 $ 10,728
Schedule of the sales credit reserve	Customer credit reserve: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 16,167 $ 11,531 $ 16,783 $ 6,784 Additions 14,211 12,164 41,596 33,714 Deductions against reserve (12,716) (12,915) (40,717) (29,718) Balance, end of period $ 17,662 $ 10,780 $ 17,662 $ 10,780

Revenue by Geographic Area (Tab

Revenue by Geographic Area (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Schedule of revenue by geographic area	Revenue by geographic area is based on the IP address or the mailing address of the customer at the time of registration. The following table sets forth revenue by geographic area: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Revenue by geographic area: (In thousands) United States $ 497,993 $ 328,056 $ 1,372,436 $ 881,984 International 242,183 119,913 626,659 331,702 Total $ 740,176 $ 447,969 $ 1,999,095 $ 1,213,686 Percentage of revenue by geographic area: United States 67 % 73 % 69 % 73 % International 33 % 27 % 31 % 27 %

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Schedule of reserved shares of common stock for issuance	The Company has reserved shares of common stock for issuance as follows: As of As of September 30, December 31, 2021 2020 Stock options issued and outstanding 4,510,986 5,625,735 Unvested restricted stock units issued and outstanding 6,467,518 7,523,882 Class A common stock reserved for Twilio.org 640,959 707,265 Stock-based awards available for grant under 2016 Plan 25,591,744 18,942,205 Stock-based awards available for grant under ESPP 6,481,649 4,941,281 Class A common stock reserved for the Convertible Notes — 7,569,731 Total 43,692,856 45,310,099

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of stock options activity	Number of Weighted- Weighted- Aggregate Outstanding options as of December 31, 2020 5,070,735 $ 51.71 6.85 $ 1,454,222 Granted 249,842 368.82 Assumed in acquisition 83,539 49.26 Exercised (1,122,523) 42.76 Forfeited and canceled (325,607) 120.73 Outstanding options as of September 30, 2021 3,955,986 $ 68.53 6.21 $ 1,002,796 Options vested and exercisable as of September 30, 2021 2,482,865 $ 28.83 5.03 $ 721,478
Schedule of weighted average grant date fair value	Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 93,920 $ 89,808 $ 359,904 $ 496,198 Total estimated grant date fair value of options vested $ 27,629 $ 12,090 $ 105,481 $ 53,110 Weighted-average grant date fair value per share of options granted or assumed in acquisition $ 331.57 $ — $ 234.74 $ 64.06 ____________________________________ ( 1 ) Aggregate intrinsic value represents the difference between the fair value of the Company’s Class A common stock as reported on the New York Stock Exchange and the exercise price of outstanding “in-the-money” options.
Schedule of restricted stock unit activity	Number of Weighted- Aggregate Unvested RSUs as of December 31, 2020 7,523,882 $ 131.76 $ 2,542,858 Granted 2,220,043 345.57 Vested (2,570,006) 101.86 Forfeited and canceled (706,401) 170.27 Unvested RSUs as of September 30, 2021 6,467,518 $ 212.83 $ 2,063,462
Schedule of unrecognized compensation	As of September 30, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 189,118 2.1 Unvested restricted stock units and awards 1,235,756 3.0 Class A shares in escrow subject to future vesting 67,821 2.2 ESPP 2,360 0.1 Total $ 1,495,055
Schedule of valuation assumptions, options	The fair value of employee stock options was estimated on the grant date using the following assumptions in the Black-Scholes option pricing model: Three Months Ended Nine Months Ended Employee Stock Options: 2021 2020 2021 2020 Fair value of common stock $342.0 - $375.4 $— $316.31 - $409.21 $108.4 - $191.9 Expected term (in years) 0.30 - 5.40 — 0.30 - 6.08 6.08 Expected volatility 42.9% - 61.5% —% 42.9% - 61.5% 51.9% - 56.0% Risk-free interest rate 0.1% - 0.9% —% 0.1% - 1.1% 0.4% - 1.4% Dividend rate —% —% —% —% Nine Months Ended Employee Stock Purchase Plan: 2021 2020 Expected term (in years) 0.5 0.5 Expected volatility 58.7% 72.1% Risk-free interest rate 0.04% 0.2% Dividend rate —% —%
Schedule of stock based compensation expense	The Company recorded total stock-based compensation expense as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (In thousands) Cost of revenue $ 3,720 $ 2,237 $ 9,461 $ 6,217 Research and development 69,242 46,294 185,072 119,344 Sales and marketing 53,843 26,573 143,419 69,602 General and administrative 37,238 14,306 107,414 42,659 Total $ 164,043 $ 89,410 $ 445,366 $ 237,822

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of the calculation of basic and diluted net loss per share attributable to common stockholders	The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Net loss attributable to common stockholders (in thousands) $ (224,109) $ (116,914) $ (658,504) $ (311,628) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 177,231,285 147,501,075 172,605,371 142,832,021 Net loss per share attributable to common stockholders, basic and diluted $ (1.26) $ (0.79) $ (3.82) $ (2.18)
Schedule of common stock equivalents excluded from the computation of the diluted net loss per share attributable to common stockholders	The following outstanding shares of common stock equivalents were excluded from the calculation of the diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive: As of September 30, 2021 2020 Stock options issued and outstanding 4,510,986 4,946,920 Restricted stock units issued and outstanding 6,467,518 8,026,189 Class A common stock reserved for Twilio.org 640,959 729,367 Class A common stock committed under ESPP 107,815 103,374 Convertible senior notes (1) — 5,013,815 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future vesting 342,784 — Total 12,145,674 18,819,665 ____________________________________ (1) During the second quarter of 2021, the remaining principal amount of the Convertible Notes was fully redeemed and as of June 30, 2021, no Convertible Notes were outstanding. As of September 30, 2020, the Company was using treasury stock method to calculate the dilutive impact of the Convertible Notes because at that time the Company expected to settle the principal amount of these notes in cash and any excess in shares of the Company’s Class A common stock. Effective with the fourth quarter 2020, the Company expected to settle the principal amount of these notes in shares of the Company’s Class A common stock, and since then used the if-converted method for calculating a potential dilutive effect on diluted net income per share, if applicable. As of September 30, 2020, the conversion spread, calculated using the average market price of Class A common stock during the period consistent with the treasury stock method, had a dilutive impact on diluted net income per share of Class A common stock when the average market price of the Company’s Class A common stock for a given period exceeded the conversion price of $70.90 per share.

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial Assets:
Cash and cash equivalents:	$ 1,161,477	$ 658,749
Amortized Cost or Carrying Value	3,894,518	2,097,504
Gross Unrealized Gains	4,218	8,538
Gross Unrealized Losses	(1,982)	(136)
Marketable securities, aggregate fair value	3,896,754	2,105,906
Total financial assets	5,055,995	2,756,253
Total financial assets	5,058,231	2,764,655
Fair Value Measurements, Liabilities
Amortized Cost or Carrying Value	0
Gross Unrealized Gains	0
Gross Unrealized Losses	(3,069)
Total financial liabilities	(3,069)
Foreign Currency Derivative
Fair Value Measurements, Liabilities
Amortized Cost or Carrying Value	0
Gross Unrealized Gains	0
Gross Unrealized Losses	(3,069)
Total financial liabilities	(3,069)
U.S. Treasury securities
Financial Assets:
Amortized Cost or Carrying Value	349,951	223,247
Gross Unrealized Gains	73	389
Gross Unrealized Losses	(353)	(1)
Marketable securities, aggregate fair value	349,671	223,635
Non-U.S. Government securities
Financial Assets:
Amortized Cost or Carrying Value	242,258
Gross Unrealized Gains	4
Gross Unrealized Losses	(249)
Marketable securities, aggregate fair value	242,013
Corporate debt securities and commercial paper
Financial Assets:
Amortized Cost or Carrying Value	3,302,309	1,874,257
Gross Unrealized Gains	4,141	8,149
Gross Unrealized Losses	(1,380)	(135)
Marketable securities, aggregate fair value	3,305,070	1,882,271
Level 1
Financial Assets:
Cash and cash equivalents:	1,087,268	656,749
Marketable securities, aggregate fair value	618,684	273,635
Total financial assets	1,705,952	930,384
Fair Value Measurements, Liabilities
Total financial liabilities	0
Level 1 | Foreign Currency Derivative
Fair Value Measurements, Liabilities
Total financial liabilities	0
Level 1 | U.S. Treasury securities
Financial Assets:
Marketable securities, aggregate fair value	349,671	223,635
Level 1 | Non-U.S. Government securities
Financial Assets:
Marketable securities, aggregate fair value	242,013
Level 1 | Corporate debt securities and commercial paper
Financial Assets:
Marketable securities, aggregate fair value	27,000	50,000
Level 2
Financial Assets:
Cash and cash equivalents:	74,209	2,000
Marketable securities, aggregate fair value	3,278,070	1,832,271
Total financial assets	3,352,279	1,834,271
Fair Value Measurements, Liabilities
Total financial liabilities	(3,069)
Level 2 | Foreign Currency Derivative
Fair Value Measurements, Liabilities
Total financial liabilities	(3,069)
Level 2 | U.S. Treasury securities
Financial Assets:
Marketable securities, aggregate fair value	0	0
Level 2 | Non-U.S. Government securities
Financial Assets:
Marketable securities, aggregate fair value	0
Level 2 | Corporate debt securities and commercial paper
Financial Assets:
Marketable securities, aggregate fair value	3,278,070	1,832,271
Level 3
Financial Assets:
Marketable securities, aggregate fair value	0	0
Total financial assets	0	0
Fair Value Measurements, Liabilities
Total financial liabilities	0
Level 3 | Foreign Currency Derivative
Fair Value Measurements, Liabilities
Total financial liabilities	0
Level 3 | U.S. Treasury securities
Financial Assets:
Marketable securities, aggregate fair value	0	0
Level 3 | Non-U.S. Government securities
Financial Assets:
Marketable securities, aggregate fair value	0
Level 3 | Corporate debt securities and commercial paper
Financial Assets:
Marketable securities, aggregate fair value	0	0
Carrying Value | Money market funds
Financial Assets:
Cash and cash equivalents:	1,087,268	656,749
Carrying Value | Commercial paper
Financial Assets:
Cash and cash equivalents:	74,209	2,000
Aggregate Fair Value | Money market funds
Financial Assets:
Cash and cash equivalents:	1,087,268	656,749
Aggregate Fair Value | Commercial paper
Financial Assets:
Cash and cash equivalents:	74,209	2,000
Aggregate Fair Value | Level 1 | Money market funds
Financial Assets:
Cash and cash equivalents:	1,087,268	656,749
Aggregate Fair Value | Level 2 | Commercial paper
Financial Assets:
Cash and cash equivalents:	$ 74,209	$ 2,000

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest earned on marketable securities	$ 16,200,000	$ 7,100,000	$ 39,500,000	$ 23,700,000
Investment in equity securities, carrying value	66,300,000		66,300,000		$ 9,300,000
Impairment of long-lived assets	0	$ 0	0	$ 0
Senior Notes 3.625 Percent Due 2029 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of the notes	512,900,000		512,900,000
Senior Notes 3.875 Percent Due 2031 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of the notes	$ 513,400,000		$ 513,400,000

Fair Value Measurements - Contr

Fair Value Measurements - Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Less than one year, amortized cost	$ 1,119,954	$ 1,126,091
One to three years, amortized cost	2,774,564	971,413
Amortized Cost or Carrying Value	3,894,518	2,097,504
Less than one year, aggregate fair value	1,121,537	1,128,927
One to three years, aggregate fair value	2,775,217	976,979
Total aggregate fair value	$ 3,896,754	$ 2,105,906

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative liabilities	$ 3.1
Foreign Currency Forward | Designated as Cash Flow Hedges
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, term of contract	6 months
Foreign Currency Forward | Designated as Cash Flow Hedges | Buy | Cash Flow Hedge
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, notional amount	$ 63.4
Foreign Currency Forward | Designated as Cash Flow Hedges | Sell | Cash Flow Hedge
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, notional amount	$ 76.7

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Gains (Losses) Associated With Foreign Currency Forward Contracts (Details) - Foreign Currency Forward - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Foreign Currency Fair Value Hedge Derivative [Line Items]
Losses recognized in OCI	$ (161)	$ (3,069)
Cost of revenue
Foreign Currency Fair Value Hedge Derivative [Line Items]
Losses recognized in income due to instruments maturing	$ (2,464)	$ (2,931)

Property and Equipment - Proper

Property and Equipment - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property and Equipment
Total property and equipment	$ 412,466	$ 313,323
Less: accumulated depreciation and amortization	(175,225)	(130,084)
Total property and equipment, net	237,241	183,239
Capitalized internal-use software development costs
Property and Equipment
Total property and equipment	185,037	142,489
Data center equipment
Property and Equipment
Total property and equipment	64,104	43,477
Leasehold improvements
Property and Equipment
Total property and equipment	80,897	69,756
Office equipment
Property and Equipment
Total property and equipment	56,291	35,346
Furniture and fixtures
Property and Equipment
Total property and equipment	15,646	12,312
Software
Property and Equipment
Total property and equipment	$ 10,491	$ 9,943

Property and Equipment - Schedu

Property and Equipment - Schedule of Supplemental Depreciation and Amortization Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 14,546	$ 12,843	$ 43,198	$ 36,674
Capitalized internal-use software development costs	17,999	12,172	49,527	36,738
Stock-based compensation capitalized in software development costs	5,198	3,696	14,938	10,711
Amortization of capitalized internal-use software development costs	$ 4,419	$ 4,380	$ 13,270	$ 13,389

Right-of-Use Asset and Lease _3

Right-of-Use Asset and Lease Liabilities - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)property
Lessee, Lease, Description [Line Items]
Number of leased properties | property	32
Renewal option	5 years
Operating lease, not yet commenced, liability	$ 11
Operating lease, not yet commenced, term of contract	6 years 2 months 12 days
Finance lease not yet commenced, liability	$ 10.5
Finance lease not yet commenced, term of contract	4 years
Minimum
Lessee, Lease, Description [Line Items]
Term of lease	2 months 12 days
Maximum
Lessee, Lease, Description [Line Items]
Term of lease	8 years

Right-of-Use Asset and Lease _4

Right-of-Use Asset and Lease Liabilities - Components of Lease Expense (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 cost	$ 16,141	$ 12,127	$ 45,519	$ 35,048
Finance lease cost:
Amortization of assets	2,905	2,384	8,389	6,118
Interest on lease liabilities	282	212	805	604
Short-term lease cost	802	1,195	3,340	3,698
Variable lease cost	2,389	2,066	7,322	5,246
Total net lease cost	$ 22,519	$ 17,984	$ 65,375	$ 50,714

Right-of-Use Asset and Lease _5

Right-of-Use Asset and Lease Liabilities - Balance Sheet Classification of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
ASSETS
Operating lease assets	$ 248,582	$ 258,610
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property and equipment, net	Property and equipment, net
Finance lease assets	$ 29,027	$ 25,771
Total leased assets	277,609	284,381
Current liabilities:
Operating	50,760	48,338
Finance	10,150	9,062
Noncurrent liabilities
Operating	223,033	229,905
Finance	20,254	17,856
Total lease liabilities	304,197	305,161
Operating lease accumulated amortization	88,900	57,100
Finance lease accumulated depreciation	$ 23,400	$ 15,000

Right-of-Use Asset and Lease _6

Right-of-Use Asset and Lease Liabilities - Supplemental Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 44,551	$ 34,124
Operating cash flows from finance leases (interest)	788	604
Financing cash flows from finance leases	$ 8,343	$ 5,721
Weighted average remaining lease term (in years):
Operating leases	5 years 8 months 12 days		5 years 7 months 6 days
Finance leases	3 years 1 month 6 days		3 years 4 months 24 days
Weighted average discount rate:
Operating leases (as a percent)	4.50%		5.30%
Finance leases (as a percent)	3.50%		4.10%

Right-of-Use Asset and Lease _7

Right-of-Use Asset and Lease Liabilities - Lease Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Maturity Of Operating Lease Liabilities
2021 (remaining three months)	$ 14,742
2022	63,245
2023	55,476
2024	50,857
2025	37,706
Thereafter	89,223
Total lease payments	311,249
Less: imputed interest	(37,456)
Total lease obligations	273,793
Less: current obligations	(50,760)	$ (48,338)
Long-term lease obligations	223,033	229,905
Maturity Of Finance Lease Liabilities
2021 (remaining three months)	2,920
2022	10,681
2023	9,934
2024	6,693
2025	1,394
Thereafter	518
Total lease payments	32,140
Less: imputed interest	(1,736)
Total lease obligations	30,404
Less: current obligations	(10,150)	(9,062)
Long-term lease obligations	$ 20,254	$ 17,856

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended
	Jul. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Acquisition
Value of equity awards assumed in acquisition		$ 1,511
Goodwill		5,263,051		$ 5,263,051	$ 4,595,394
Zipwhip
Acquisition
Purchase price, as adjusted	$ 838,448
Payments to acquire businesses, gross	417,900
Fair value of Class A common stock transferred	$ 419,037
Shares issuable as part of acquisition (in shares)	1,200,000
Value of equity awards assumed in acquisition	$ 1,511
Business combination, contingent consideration	$ 19,100
Business combination, contingent consideration, term	3 years
Fair value of unvested employee shares	$ 30,700
Net deferred tax liability	18,100	18,144		18,144
Operating right-of-use assets acquired, decrease during period	$ 1,700
Revenues		23,600
Intangible assets		244,500		244,500
Goodwill		600,070		600,070
Zipwhip | General and administrative
Acquisition
Acquisition related costs		$ 1,600		$ 4,200
Zipwhip | Common Stock Class A
Acquisition
Shares issuable as part of acquisition (in shares)	1,100,000
Shares subject to future vesting conditions (in shares)	59,533
Weighted average remaining contractual term	3 years
Other Acquisitions
Acquisition
Purchase price, as adjusted			$ 100,200
Intangible assets			37,000
Goodwill			$ 63,400

Business Combinations - Purchas

Business Combinations - Purchase Price Components (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jul. 31, 2021	Sep. 30, 2021
Business Acquisition [Line Items]
Value of equity awards assumed in acquisition		$ 1,511
Zipwhip
Business Acquisition [Line Items]
Fair value of Class A common stock transferred	$ 419,037
Payments to acquire businesses, gross	417,900
Value of equity awards assumed in acquisition	1,511
Total purchase price, as adjusted	$ 838,448

Business Combinations - Purch_2

Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jul. 31, 2021	Dec. 31, 2020
Acquisition
Goodwill	$ 5,263,051		$ 4,595,394
Zipwhip
Acquisition
Cash and cash equivalents	21,610
Accounts receivable and other current assets	11,481
Property and equipment, net	2,950
Operating right-of-use asset	23,545
Intangible assets	244,500
Other assets	370
Goodwill	600,070
Accounts payable and other liabilities	(20,239)
Deferred revenue	(4,526)
Operating lease liability	(23,169)
Deferred tax liability	(18,144)	$ (18,100)
Total purchase price	$ 838,448

Business Combinations - Identif

Business Combinations - Identifiable Finite-lived Intangible Assets (Details) - Zipwhip $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Acquisitions
Intangible assets	$ 244,500
Developed technology
Acquisitions
Intangible assets	$ 56,800
Intangible assets, estimated life	7 years
Customer relationships
Acquisitions
Intangible assets	$ 147,700
Intangible assets, estimated life	10 years
Supplier relationships
Acquisitions
Intangible assets	$ 39,600
Intangible assets, estimated life	5 years
Trade names
Acquisitions
Intangible assets	$ 400
Intangible assets, estimated life	5 years

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill Rollforward (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Balance (beginning of period)	$ 4,595,394
Goodwill additions and adjustments	667,657
Balance (end of period)	$ 5,263,051

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortizable intangible assets:
Gross	$ 1,429,506	$ 1,147,219
Accumulated Amortization	(332,122)	(185,861)
Net	1,097,384	961,358
Intangible assets, gross	1,434,721	1,152,434
Total	1,102,599	966,573
Telecommunication licenses
Amortizable intangible assets:
Non-amortizable intangible assets:	4,920	4,920
Trademarks and other
Amortizable intangible assets:
Non-amortizable intangible assets:	295	295
Developed technology
Amortizable intangible assets:
Gross	794,831	724,599
Accumulated Amortization	(194,285)	(113,282)
Net	600,546	611,317
Customer relationships
Amortizable intangible assets:
Gross	538,264	379,344
Accumulated Amortization	(108,953)	(59,574)
Net	429,311	319,770
Supplier relationships
Amortizable intangible assets:
Gross	51,671	4,356
Accumulated Amortization	(6,916)	(3,044)
Net	44,755	1,312
Trade names
Amortizable intangible assets:
Gross	30,669	25,560
Accumulated Amortization	(12,327)	(7,921)
Net	18,342	17,639
Order or Production Backlog [Member]
Amortizable intangible assets:
Gross	10,000	10,000
Accumulated Amortization	(9,167)	(1,667)
Net	833	8,333
Patent
Amortizable intangible assets:
Gross	4,071	3,360
Accumulated Amortization	(474)	(373)
Net	$ 3,597	$ 2,987

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Amortization Expense (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	$ 55.7	$ 20.4	$ 146.3	$ 61.3

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Total Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Intangible Assets
2021 (remaining three months)	$ 52,554
2022	204,832
2023	201,522
2024	195,948
2025	192,374
Thereafter	250,154
Net	$ 1,097,384	$ 961,358

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Accrued payroll and related	$ 66,094	$ 54,683
Accrued bonus and commission	36,155	25,341
Accrued cost of revenue	115,996	80,620
Sales and other taxes payable	63,660	48,390
ESPP contributions	19,354	6,272
Finance lease liability, current	10,150	9,062
Accrued other expense	57,274	28,527
Total accrued expenses and other current liabilities	$ 368,683	$ 252,895

Accrued Expenses and Other Li_4

Accrued Expenses and Other Liabilities - Long-term Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Deferred tax liability	$ 20,446	$ 13,684
Acquisition holdback	8,502	8,800
Accrued other expenses	20,243	14,149
Total other long-term liabilities	$ 49,191	$ 36,633

Notes Payable - Summary of Long

Notes Payable - Summary of Long-Term Debt (Details) - USD ($)	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Net carrying amount	$ 985,547,000		$ 302,068,000
Senior Notes 3.625 Percent Due 2029
Debt Instrument [Line Items]
Principal	500,000,000	$ 500,000,000	0
Unamortized discount	(5,872,000)		0
Unamortized issuance costs	(1,316,000)		0
Net carrying amount	492,812,000		0
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Principal	500,000,000	$ 500,000,000	0
Unamortized discount	(5,962,000)		0
Unamortized issuance costs	(1,303,000)		0
Net carrying amount	492,735,000		0
Convertible senior notes due 2023
Debt Instrument [Line Items]
Principal	0		343,702,000
Unamortized discount	0		(38,406,000)
Unamortized issuance costs	0		(3,228,000)
Net carrying amount	$ 0		$ 302,068,000

Notes Payable - Issuance (Detai

Notes Payable - Issuance (Details) - USD ($)	1 Months Ended
	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Senior Notes
Debt Instrument [Line Items]
Principal	$ 1,000,000,000
Net proceeds from the debt offering	985,100,000
Debt issuance costs, gross	2,400,000
Senior Notes 3.625 Percent Due 2029
Debt Instrument [Line Items]
Principal	$ 500,000,000	$ 500,000,000	$ 0
Interest rate (as a percent)	3.625%
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Principal	$ 500,000,000	$ 500,000,000	$ 0
Interest rate (as a percent)	3.875%

Notes Payable - Terms (Details)

Notes Payable - Terms (Details)	9 Months Ended
	Sep. 30, 2021
Senior Notes | Change of control event
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.00%
Senior Notes 3.625 Percent Due 2029 | Redemption Period One
Debt Instrument [Line Items]
Debt instrument, maximum redemption price as a percentage of principal 180 days after equity offer	40.00%
Debt instrument, minimum redemption price as a percentage of principal outstanding	50.00%
Senior Notes 3.625 Percent Due 2029 | Redemption Period One | Maximum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	103.625%
Senior Notes 3.625 Percent Due 2029 | Redemption Period One | Minimum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Notes 3.625 Percent Due 2029 | Redemption Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.813%
Senior Notes 3.625 Percent Due 2029 | Redemption Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.906%
Senior Notes 3.625 Percent Due 2029 | Redemption Period Four
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Notes 3.875 Percent Due 2031 | Redemption Period One
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	103.875%
Debt instrument, maximum redemption price as a percentage of principal 180 days after equity offer	40.00%
Debt instrument, minimum redemption price as a percentage of principal outstanding	50.00%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.938%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Four
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.292%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Five
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.646%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Six
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%

Notes Payable - Interest Expens

Notes Payable - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Interest expense recognized related to the Notes
Total interest expense	$ 9,809	$ 21,882
Senior Notes 3.625 Percent Due 2029
Interest expense recognized related to the Notes
Contractual interest expense	4,531	10,182
Amortization of debt discount and issuance costs	246	463
Total interest expense	4,777	10,645
Senior Notes 3.875 Percent Due 2031
Interest expense recognized related to the Notes
Contractual interest expense	4,844	10,885
Amortization of debt discount and issuance costs	188	352
Total interest expense	$ 5,032	$ 11,237

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allowance for doubtful accounts
Balance, beginning of period	$ 15,413	$ 10,248	$ 12,046	$ 6,287
Additions	4,122	1,312	13,490	8,472
Write-offs	(2,703)	(832)	(8,704)	(4,031)
Balance, end of period	$ 16,832	$ 10,728	$ 16,832	$ 10,728

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Sales Credit Reserve (Details) - Sales credit reserve - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Sales credit reserve
Balance, beginning of period	$ 16,167	$ 11,531	$ 16,783	$ 6,784
Additions	14,211	12,164	41,596	33,714
Deductions against reserve	(12,716)	(12,915)	(40,717)	(29,718)
Balance, end of period	$ 17,662	$ 10,780	$ 17,662	$ 10,780

Revenue by Geographic Area - Re

Revenue by Geographic Area - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue by geographic area:
Revenue	$ 740,176	$ 447,969	$ 1,999,095	$ 1,213,686
United States
Revenue by geographic area:
Revenue	497,993	328,056	1,372,436	881,984
International
Revenue by geographic area:
Revenue	$ 242,183	$ 119,913	$ 626,659	$ 331,702

Revenue by Geographic Area - Pe

Revenue by Geographic Area - Percentage of Revenue by Geographic Area (Details) - Revenue from Contract with Customer Benchmark - Geographic Concentration Risk	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
United States
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	67.00%	73.00%	69.00%	73.00%
International
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	33.00%	27.00%	31.00%	27.00%

Commitments and Contingencies -

Commitments and Contingencies - Other Commitments (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 31, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Long-term Purchase Commitment [Line Items]
Term of non-cancelable agreement		4 years	4 years
Purchase commitment		$ 9,000,000	$ 9,000,000	$ 447,000,000
Payments to acquire investments			3,225,799,000	$ 1,465,158,000
Syniverse
Long-term Purchase Commitment [Line Items]
Payments to acquire investments	$ 750,000,000
Deferred costs		$ 4,800,000	$ 4,800,000
Minimum
Long-term Purchase Commitment [Line Items]
Term of non-cancelable lease			1 year
Minimum | Syniverse
Long-term Purchase Commitment [Line Items]
Common stock, value, subscriptions	500,000,000
Maximum
Long-term Purchase Commitment [Line Items]
Term of non-cancelable lease			8 years
Maximum | Syniverse
Long-term Purchase Commitment [Line Items]
Common stock, value, subscriptions	$ 750,000,000

Commitments and Contingencies_2

Commitments and Contingencies - Legal Matters and Indemnification Agreements (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Taxes payable, jurisdictional estimate	$ 38,800,000
Indemnification Agreements
Loss Contingencies [Line Items]
Amount accrued	$ 0	$ 0

Commitments and Contingencies_3

Commitments and Contingencies - Other taxes (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Taxes payable, jurisdictional estimate	$ 38.8
Accrued taxes	11.5
Domestic Tax Authority
Loss Contingencies [Line Items]
Taxes payable	27.9	$ 25.6
Foreign Tax Authority
Loss Contingencies [Line Items]
Taxes payable	$ 15.3	$ 9.6

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Preferred Stock
Preferred stock, authorized (in shares)	100,000,000	100,000,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details)	Sep. 30, 2021vote$ / sharesshares	Dec. 31, 2020vote$ / sharesshares
Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common Stock Class A
Common Stock
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, issued (in shares)	168,352,933	153,496,222
Common stock, outstanding (in shares)	168,352,933	153,496,222
Votes per share | vote		1
Common Stock Class B
Common Stock
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	9,913,181	10,551,302
Common stock, outstanding (in shares)	9,913,181	10,551,302
Votes per share | vote	10

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Shares Reserved (Details) - shares	Sep. 30, 2021	Dec. 31, 2020
Stockholders' Equity
Total (in shares)	43,692,856	45,310,099
2016 Stock Option and Incentive Plan
Stockholders' Equity
Stock-based awards available for grant under 2016 Plan (in shares)	25,591,744	18,942,205
Common Stock Class A
Stockholders' Equity
Class A common stock reserved for Twilio.org (in shares)	640,959	707,265
Class A common stock reserved for the convertible senior notes (in shares)	0	7,569,731
Stock options issued and outstanding
Stockholders' Equity
Stock options issued and outstanding (in shares)	4,510,986	5,625,735
Restricted stock units issued and outstanding
Stockholders' Equity
Unvested restricted stock units and awards issued and outstanding (in shares)	6,467,518	7,523,882
Class A common stock committed under ESPP
Stockholders' Equity
Stock-based awards available for grant under 2016 Plan (in shares)	6,481,649	4,941,281

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2021	Dec. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021
Stock Based Compensation
Stock plan offering period					6 months
Class A common stock committed under ESPP
Stock Based Compensation
Increase in shares available for grant (in shares)	1,640,475
Weighted-average period (in years)					1 month 6 days
Class A common stock committed under ESPP | Common Stock
Stock Based Compensation
Shares purchased in period (in shares)			0	0
Class A common stock committed under ESPP | Common Stock | Forecast
Stock Based Compensation
Shares purchased in period (in shares)		107,815
Performance-based stock options
Stock Based Compensation
Granted (in shares)					555,000
Outstanding options as of the end of the period (in dollars per share)			$ 31.72		$ 31.72
Options vested and exercisable - number of options outstanding (in shares)			555,000		555,000
RSAs
Stock Based Compensation
Granted (in shares)					24,697
Granted (in dollars per share)					$ 359.80
Outstanding RSUs, aggregate intrinsic value			$ 7.8		$ 7.8
Class A shares in escrow subject to future vesting
Stock Based Compensation
Outstanding RSUs, aggregate intrinsic value			$ 101.5		$ 101.5
Shares subject to future vesting conditions (in shares)					318,087
Weighted-average period (in years)					2 years 2 months 12 days
Shares subject to future vesting conditions, weighted average grant date fair value (in dollars per share)					$ 292.46
2016 Stock Option and Incentive Plan
Stock Based Compensation
Increase in shares available for grant (in shares)	8,202,376

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - Employee and nonemployee stock options $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Number of options outstanding
Outstanding options as of the beginning of the period (in shares) | shares	5,070,735
Granted (in shares) | shares	249,842
Assumed in acquisition (in shares) | shares	83,539
Exercised (in shares) | shares	(1,122,523)
Forfeited and cancelled (in shares) | shares	(325,607)
Outstanding options as of the end of the period (in shares) | shares	3,955,986	5,070,735
Weighted- average exercise price (Per share)
Outstanding options as of the beginning of the period (in dollars per share) | $ / shares	$ 51.71
Granted (in dollars per share) | $ / shares	368.82
Assumed in acquisition (in dollars per share) | $ / shares	49.26
Exercised (in dollars per share) | $ / shares	42.76
Forfeited and cancelled (in dollars per share) | $ / shares	120.73
Outstanding options as of the end of the period (in dollars per share) | $ / shares	$ 68.53	$ 51.71
Weighted- average remaining contractual term (In years)
Weighted-average remaining contractual term (in years)	6 years 2 months 15 days	6 years 10 months 6 days
Aggregate intrinsic value | $	$ 1,002,796	$ 1,454,222
Options vested and exercisable and options vested and expected to vest
Options vested and exercisable - number of options outstanding (in shares) | shares	2,482,865
Options vested and exercisable - weighted-average exercise price (in dollars per share) | $ / shares	$ 28.83
Options vested and exercisable - weighted-average remaining contractual term	5 years 10 days
Options vested and exercisable - aggregate intrinsic value | $	$ 721,478

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options - Additional Information (Details) - Employee and nonemployee stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock Based Compensation
Aggregate intrinsic value of stock options exercised	$ 93,920	$ 89,808	$ 359,904	$ 496,198
Total estimated grant date fair value of options vested	$ 27,629	$ 12,090	$ 105,481	$ 53,110
Weighted-average grant date fair value per share of options granted or assumed in acquisition (in dollars per share)	$ 331.57	$ 0	$ 234.74	$ 64.06

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted stock units issued and outstanding - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Number of awards outstanding
Unvested RSUs at the beginning of the period (in shares)	7,523,882
Granted (in shares)	2,220,043
Vested (in shares)	(2,570,006)
Forfeited and canceled (in shares)	(706,401)
Unvested RSUs at the end of the period (in shares)	6,467,518
Weighted- average grant date fair value (Per share)
Unvested RSUs at the beginning of the period (in dollars per share)	$ 131.76
Granted (in dollars per share)	345.57
Vested (in dollars per share)	101.86
Forfeited and canceled (in dollars per share)	170.27
Unvested RSUs at the end of the period (in dollars per share)	$ 212.83
Aggregate intrinsic value
Aggregate intrinsic value	$ 2,063,462	$ 2,542,858

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Units - Unrecognized Compensation Cost (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Stock Based Compensation
Total	$ 1,495,055
Unvested stock options
Stock Based Compensation
Unvested stock options	$ 189,118
Weighted-average period (in years)	2 years 1 month 6 days
Unvested restricted stock units and awards
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 1,235,756
Weighted-average period (in years)	3 years
Class A shares in escrow subject to future vesting
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 67,821
Weighted-average period (in years)	2 years 2 months 12 days
ESPP
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 2,360
Weighted-average period (in years)	1 month 6 days

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee stock options
Valuation Assumptions
Expected term (in years)				6 years 29 days
Expected volatility, low end of range (as a percent)	42.90%	0.00%	42.90%	51.90%
Expected volatility, high end of range (as a percent)	61.50%		61.50%	56.00%
Risk-free interest rate, low end of range (as a percent)	0.10%		0.10%	0.40%
Risk-free interest rate, high end of range (as a percent)	0.90%		1.10%	1.40%
Risk-free interest rate (as a percent)		0.00%
Dividend rate (as a percent)	0.00%	0.00%	0.00%	0.00%
Class A common stock committed under ESPP
Valuation Assumptions
Expected term (in years)			6 months	6 months
Expected volatility (as a percent)			58.70%	72.10%
Risk-free interest rate (as a percent)			0.04%	0.20%
Dividend rate (as a percent)			0.00%	0.00%
Minimum | Employee stock options
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 342	$ 0	$ 316.31	$ 108.4
Expected term (in years)	3 months 18 days		3 months 18 days
Maximum | Employee stock options
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 375.4		$ 409.21	$ 191.9
Expected term (in years)	5 years 4 months 24 days		6 years 29 days

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock-Based Compensation Expense
Stock-based compensation expense	$ 164,043	$ 89,410	$ 445,366	$ 237,822
Cost of revenue
Stock-Based Compensation Expense
Stock-based compensation expense	3,720	2,237	9,461	6,217
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense	69,242	46,294	185,072	119,344
Sales and marketing
Stock-Based Compensation Expense
Stock-based compensation expense	53,843	26,573	143,419	69,602
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense	$ 37,238	$ 14,306	$ 107,414	$ 42,659

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Loss Per Share Attributable to Common Stockholders
Net loss attributable to common stockholders, basic	$ (224,109)	$ (116,914)	$ (658,504)	$ (311,628)
Net loss attributable to common stockholders, diluted	$ (224,109)	$ (116,914)	$ (658,504)	$ (311,628)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic (in shares)	177,231,285	147,501,075	172,605,371	142,832,021
Weighted-average shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	177,231,285	147,501,075	172,605,371	142,832,021
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (1.26)	$ (0.79)	$ (3.82)	$ (2.18)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (1.26)	$ (0.79)	$ (3.82)	$ (2.18)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Anti-Dilutive Securities (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Anti-dilutive securities
Antidilutive securities (in shares)	12,145,674	18,819,665
Common Stock Class A
Anti-dilutive securities
Conversion price (in dollars per share)	$ 70.90
Stock options issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	4,510,986	4,946,920
Restricted stock units issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	6,467,518	8,026,189
Class A common stock reserved for Twilio.org
Anti-dilutive securities
Antidilutive securities (in shares)	640,959	729,367
Class A common stock committed under ESPP
Anti-dilutive securities
Antidilutive securities (in shares)	107,815	103,374
Convertible senior notes
Anti-dilutive securities
Antidilutive securities (in shares)	0	5,013,815
Class A common stock in escrow
Anti-dilutive securities
Antidilutive securities (in shares)	75,612	0
Class A common stock in escrow and restricted stock awards subject to future vesting
Anti-dilutive securities
Antidilutive securities (in shares)	342,784	0

Income Taxes (Details)

Income Taxes (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 (benefit)	$ (14,849)	$ 648	$ (12,673)	$ 1,919