Twilio (TWLO) 10-Q 30 Jul 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 23, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Annual Report	true
Document Period End Date	Jun. 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	Q2
Common Stock Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		166,931,325
Common Stock Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		10,218,422

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,799,602	$ 933,885
Short-term marketable securities	4,125,583	2,105,906
Accounts receivable, net	301,548	251,167
Prepaid expenses and other current assets	146,955	81,377
Total current assets	6,373,688	3,372,335
Property and equipment, net	206,354	183,239
Operating right-of-use asset	233,449	258,610
Intangible assets, net	913,308	966,573
Goodwill	4,664,185	4,595,394
Other long-term assets	142,601	111,282
Total assets	12,533,585	9,487,433
Current liabilities:
Accounts payable	105,998	60,042
Accrued expenses and other current liabilities	331,804	252,895
Deferred revenue and customer deposits	98,723	87,031
Operating lease liability, current	46,760	48,338
Total current liabilities	583,285	448,306
Operating lease liability, noncurrent	205,997	229,905
Finance lease liability, noncurrent	17,804	17,856
Long-term debt	985,219	302,068
Other long-term liabilities	47,168	36,633
Total liabilities	1,839,473	1,034,768
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock	0	0
Class A and Class B common stock	176	164
Additional paid-in capital	12,297,415	9,613,246
Accumulated other comprehensive income	707	9,046
Accumulated deficit	(1,604,186)	(1,169,791)
Total stockholders’ equity	10,694,112	8,452,665
Total liabilities and stockholders’ equity	$ 12,533,585	$ 9,487,433

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue	$ 668,931	$ 400,849	$ 1,258,919	$ 765,717
Cost of revenue	337,684	191,718	629,368	363,051
Gross profit	331,247	209,131	629,551	402,666
Operating expenses:
Research and development	181,280	120,701	356,080	235,040
Sales and marketing	238,058	129,823	448,648	246,545
General and administrative	114,183	61,251	224,436	116,421
Total operating expenses	533,521	311,775	1,029,164	598,006
Loss from operations	(202,274)	(102,644)	(399,613)	(195,340)
Other (expenses) income, net	(24,293)	3,015	(32,606)	1,897
Loss before provision for income taxes	(226,567)	(99,629)	(432,219)	(193,443)
Provision for income taxes	(1,286)	(294)	(2,176)	(1,271)
Net loss attributable to common stockholders	$ (227,853)	$ (99,923)	$ (434,395)	$ (194,714)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (1.31)	$ (0.71)	$ (2.55)	$ (1.39)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (1.31)	$ (0.71)	$ (2.55)	$ (1.39)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic (in shares)	173,407,187	141,618,541	170,275,609	140,512,351
Weighted-average shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	173,407,187	141,618,541	170,275,609	140,512,351

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (227,853)	$ (99,923)	$ (434,395)	$ (194,714)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities	(979)	17,895	(5,155)	8,520
Foreign currency translation	(66)	0	(276)	0
Net change in market value of effective foreign currency forward exchange contracts	(2,908)	0	(2,908)	0
Total other comprehensive (loss) income	(3,953)	17,895	(8,339)	8,520
Comprehensive loss attributable to common stockholders	$ (231,806)	$ (82,028)	$ (442,734)	$ (186,194)

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	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	(194,714)
Unrealized (loss) gain on marketable securities	8,520
Foreign currency translation	0
Net change in market value of effective foreign currency forward exchange contracts	0
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)
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)
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)
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
Foreign currency translation	0
Net change in market value of effective foreign currency forward exchange contracts	0
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)
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)
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	(434,395)
Equity component from partial settlement of 2023 convertible senior notes (in shares)		3,688,584
Issuance of restricted stock awards (in shares)		24,697
Unrealized (loss) gain on marketable securities	(5,155)
Foreign currency translation	(276)
Net change in market value of effective foreign currency forward exchange contracts	(2,908)
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)
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)
Shares issued under ESPP (in shares)		100,107
Shares issued under ESPP	23,699			23,699
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
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)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (434,395)	$ (194,714)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	119,405	64,772
Non-cash reduction to the right-of-use asset	23,200	17,804
Net amortization of investment premium and discount	13,834	1,147
Amortization of debt discount and issuance costs	5,081	12,356
Stock-based compensation	281,323	148,412
Amortization of deferred commissions	12,394	4,819
Allowance for credit losses	7,667	7,115
Value of donated common stock	16,194	6,673
Loss on extinguishment of debt	28,986	0
Other adjustments	646	534
Changes in operating assets and liabilities:
Accounts receivable	(41,687)	(47,766)
Prepaid expenses and other current assets	(44,604)	(12,001)
Other long-term assets	(39,118)	(19,774)
Accounts payable	27,078	(11,523)
Accrued expenses and other current liabilities	65,923	47,435
Deferred revenue and customer deposits	7,615	2,994
Operating lease liabilities	(23,610)	(16,340)
Other long-term liabilities	290	1,968
Net cash provided by operating activities	26,222	13,911
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired and other related payments	(94,178)	(2,725)
Purchases of marketable securities and other investments	(2,807,798)	(443,816)
Proceeds from sales and maturities of marketable securities	754,466	621,754
Capitalized software development costs	(21,839)	(17,651)
Purchases of long-lived and intangible assets	(12,140)	(12,797)
Net cash (used in) provided by investing activities	(2,181,489)	144,765
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from a public equity offering	1,766,400	0
Payments of costs related to public offerings	(394)	0
Proceeds from issuance of senior notes	987,500	0
Payments of debt issuance costs	(1,362)	0
Proceeds from settlement of capped call, net of settlement costs	228,412	0
Principal payments on debt and finance leases	(6,658)	(3,829)
Proceeds from exercises of stock options and shares issued in ESPP	55,614	69,936
Value of equity awards withheld for tax liabilities	(4,656)	(2,818)
Net cash provided by financing activities	3,024,856	63,289
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(143)	0
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	869,446	221,965
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Beginning of period	933,885	253,735
CASH, CASH EQUIVALENTS AND RESTRICTED CASH —End of period	1,803,331	475,700
Supplemental Cash Flow Information [Abstract]
Cash paid for income taxes, net	3,240	1,022
Cash paid for interest	693	1,078
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property, equipment and intangible assets, accrued but not paid	5,254	4,545
Purchases of property and equipment through finance leases	5,266	5,366
Value of common stock issued to settle convertible senior notes	1,704,969	0
Stock-based compensation capitalized in software development costs	9,740	7,015
Costs related to public offerings and investments, accrued but not paid	3,526	0
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	1,799,602	475,700
Restricted cash in other current assets	2,620	0
Restricted cash in other long-term assets	1,109	0
Total cash, cash equivalents and restricted cash	$ 1,803,331	$ 475,700

Organization and Description of

Organization and Description of Business	6 Months Ended
	Jun. 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, Serbia, Singapore, Spain, Sweden, the United Kingdom and the United States.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 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 six months ended June 30, 2021 and 2020, no customer organization accounted for more than 10% of the Company’s total revenue. As of June 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 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, 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	6 Months Ended
	Jun. 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 $ 1,191,640 $ — $ — $ 1,191,640 $ — $ — $ 1,191,640 Commercial paper 177,609 — — — 177,609 — 177,609 Total included in cash and cash equivalents 1,369,249 — — 1,191,640 177,609 — 1,369,249 Marketable securities: U.S. Treasury securities 415,676 125 (434) 415,367 — — 415,367 Non-U.S. Government securities 237,875 2 (264) 237,613 — — 237,613 Corporate debt securities and commercial paper 3,468,815 5,206 (1,418) 47,000 3,425,603 — 3,472,603 Total marketable securities 4,122,366 5,333 (2,116) 699,980 3,425,603 — 4,125,583 Total financial assets $ 5,491,615 $ 5,333 $ (2,116) $ 1,891,620 $ 3,603,212 $ — $ 5,494,832 Financial Liabilities: Accrued expenses and other current liabilities: Foreign currency derivative liabilities $ — $ — $ (2,908) $ — $ (2,908) $ — $ (2,908) Total financial liabilities $ — $ — $ (2,908) $ — $ (2,908) $ — $ (2,908) 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 June 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 June 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 June 30, 2021, the risk of expected credit losses was not significant. Interest earned on marketable securities was $5.6 million and $9.4 million in the three and six months ended June 30, 2021, respectively, and $7.8 million and $16.6 million in the three and six months ended June 30, 2020, respectively. The interest is recorded as other (expenses) income, net, in the accompanying condensed consolidated statements of operations. The following table summarizes the contractual maturities of marketable securities: As of June 30, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,375,453 $ 1,377,906 $ 1,126,091 $ 1,128,927 One to three years 2,746,913 2,747,677 971,413 976,979 Total $ 4,122,366 $ 4,125,583 $ 2,097,504 $ 2,105,906 Strategic Investments As of June 30, 2021 and December 31, 2020, the Company held strategic investments with a fair value of $12.3 million and $9.3 million, respectively, in equity securities of privately held companies in which the Company does not have a controlling interest or significant influence. These securities are recorded as other long-term assets in the accompanying condensed consolidated balance sheets. There were no impairments in the three and six months ended June 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 during the quarter and were no longer outstanding as of June 30, 2021. Refer to Note 10 for further details on these financial liabilities. As of June 30, 2021, the fair values of the 2029 Notes and 2031 Notes were $518.2 million and $521.7 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	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Company entered into its first cash flow hedge transaction in the second quarter 2021. As of June 30, 2021, the Company had outstanding foreign currency forward contracts designated as cash flow hedges with total buy and sell notional values of $110.0 million and $133.9 million, respectively. The notional value represents the amount that will be purchased or sold upon maturity of the forward contract. As of June 30, 2021, these contracts had maturities of less than 6 months and the $2.9 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 Six Months Ended 2021 2021 (In thousands) Losses recognized in OCI Net change in market value of effective foreign currency forward exchange contracts $ (2,908) $ (2,908) Losses recognized in income (effective portion) Cost of revenue $ (467) $ (467)

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following: As of As of June 30, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 169,887 $ 142,489 Data center equipment (1) 52,460 43,477 Leasehold improvements 73,229 69,756 Office equipment 50,902 35,346 Furniture and fixtures (1) 13,769 12,312 Software 10,235 9,943 Total property and equipment 370,482 313,323 Less: accumulated depreciation and amortization (164,128) (130,084) Total property and equipment, net $ 206,354 $ 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Depreciation and amortization expense $ 14,247 $ 11,912 $ 28,652 $ 23,831 Capitalized internal-use software development costs $ 16,493 $ 12,593 $ 31,528 $ 24,565 Stock based compensation costs included in capitalized internal-use software development costs $ 5,089 $ 3,597 $ 9,740 $ 7,015 Amortization of capitalized internal-use software development costs $ 4,319 $ 4,421 $ 8,851 $ 9,010

Right-of-Use Asset and Lease Li

Right-of-Use Asset and Lease Liabilities	6 Months Ended
	Jun. 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 June 30, 2021, the Company had 27 leased properties with remaining lease terms ranging from 0.4 years to 7.8 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 14,505 $ 12,497 $ 29,378 $ 22,921 Finance lease cost: Amortization of assets 2,804 1,830 5,484 3,734 Interest on lease liabilities 260 194 523 392 Short-term lease cost 846 1,091 2,538 2,503 Variable lease cost 2,033 1,884 4,933 3,180 Total net lease cost $ 20,448 $ 17,496 $ 42,856 $ 32,730 Supplemental balance sheet information related to leases was as follows: As of As of June 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 233,449 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 25,553 25,771 Total leased assets $ 259,002 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,760 $ 48,338 Finance Finance lease liability, current 8,877 9,062 Noncurrent Operating Operating lease liability, noncurrent 205,997 229,905 Finance Finance lease liability, noncurrent 17,804 17,856 Total lease liabilities $ 279,438 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $75.9 million and $57.1 million as of June 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $20.5 million and $15.0 million as of June 30, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Six Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 29,233 $ 22,199 Operating cash flows from finance leases (interest) $ 523 $ 392 Financing cash flows from finance leases $ 5,503 $ 3,718 Weighted average remaining lease term (in years): Operating leases 5.7 5.8 Finance leases 3.2 3.2 Weighted average discount rate: Operating leases 4.8 % 5.4 % Finance leases 3.6 % 4.8 % Maturities of lease liabilities were as follows: As of June 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining six months) $ 28,031 $ 5,012 2022 58,023 8,987 2023 50,259 8,240 2024 45,716 4,999 2025 32,464 547 Thereafter 75,332 516 Total lease payments 289,825 28,301 Less: imputed interest (37,068) (1,620) Total lease obligations 252,757 26,681 Less: current obligations (46,760) (8,877) Long-term lease obligations $ 205,997 $ 17,804
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 June 30, 2021, the Company had 27 leased properties with remaining lease terms ranging from 0.4 years to 7.8 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 14,505 $ 12,497 $ 29,378 $ 22,921 Finance lease cost: Amortization of assets 2,804 1,830 5,484 3,734 Interest on lease liabilities 260 194 523 392 Short-term lease cost 846 1,091 2,538 2,503 Variable lease cost 2,033 1,884 4,933 3,180 Total net lease cost $ 20,448 $ 17,496 $ 42,856 $ 32,730 Supplemental balance sheet information related to leases was as follows: As of As of June 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 233,449 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 25,553 25,771 Total leased assets $ 259,002 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,760 $ 48,338 Finance Finance lease liability, current 8,877 9,062 Noncurrent Operating Operating lease liability, noncurrent 205,997 229,905 Finance Finance lease liability, noncurrent 17,804 17,856 Total lease liabilities $ 279,438 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $75.9 million and $57.1 million as of June 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $20.5 million and $15.0 million as of June 30, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Six Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 29,233 $ 22,199 Operating cash flows from finance leases (interest) $ 523 $ 392 Financing cash flows from finance leases $ 5,503 $ 3,718 Weighted average remaining lease term (in years): Operating leases 5.7 5.8 Finance leases 3.2 3.2 Weighted average discount rate: Operating leases 4.8 % 5.4 % Finance leases 3.6 % 4.8 % Maturities of lease liabilities were as follows: As of June 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining six months) $ 28,031 $ 5,012 2022 58,023 8,987 2023 50,259 8,240 2024 45,716 4,999 2025 32,464 547 Thereafter 75,332 516 Total lease payments 289,825 28,301 Less: imputed interest (37,068) (1,620) Total lease obligations 252,757 26,681 Less: current obligations (46,760) (8,877) Long-term lease obligations $ 205,997 $ 17,804

Business Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business Combinations Ionic Security, Inc. On April 9, 2021, the Company acquired Ionic Security, Inc. (“Ionic”), a data security platform based in Atlanta, Georgia, for a purchase price of $30.2 million paid in cash. The acquisition was accounted for as a business combination. The acquired entity’s results of operations were included in the Company’s condensed consolidated financial statements from the date of the acquisition. 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.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The Goodwill balance as of June 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 68,791 Balance as of June 30, 2021 $ 4,664,185 Intangible assets Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 738,031 $ (165,502) $ 572,529 Customer relationships 390,564 (89,466) 301,098 Supplier relationships 12,071 (3,815) 8,256 Trade names 30,269 (10,544) 19,725 Order backlog 10,000 (6,667) 3,333 Patent 3,594 (442) 3,152 Total amortizable intangible assets 1,184,529 (276,436) 908,093 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,189,744 $ (276,436) $ 913,308 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 $45.4 million and $90.6 million for the three and six months ended June 30, 2021, respectively, and $20.6 million and $40.9 million for the three and six months ended June 30, 2020, respectively. Total estimated future amortization expense is as follows: As of Year Ended December 31, (In thousands) 2021 (remaining six months) $ 92,810 2022 173,946 2023 170,636 2024 165,062 2025 161,531 Thereafter 144,108 Total $ 908,093

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	6 Months Ended
	Jun. 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 June 30, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 63,154 $ 54,683 Accrued bonus and commission 29,319 25,341 Accrued cost of revenue 96,959 80,620 Sales and other taxes payable 55,914 48,390 ESPP contributions 7,605 6,272 Finance lease liability, current 8,877 9,062 Accrued other expense 69,976 28,527 Total accrued expenses and other current liabilities $ 331,804 $ 252,895 Other long-term liabilities consisted of the following: As of As of June 30, December 31, 2021 2020 (In thousands) Deferred tax liability $ 19,380 $ 13,684 Acquisition holdback 10,623 8,800 Accrued other expenses 17,165 14,149 Total other long-term liabilities $ 47,168 $ 36,633

Notes Payable

Notes Payable	6 Months Ended
	Jun. 30, 2021
Long-term Debt, Unclassified [Abstract]
Notes Payable	Notes Payable Long-term debt consisted of the following: As of As of June 30, December 31, 2021 2020 (In thousands) 2029 and 2031 Senior Notes 2029 Senior Notes Principal $ 500,000 $ — Unamortized discount (6,041) — Unamortized issuance costs (1,323) — Net carrying amount 492,636 — 2031 Senior Notes Principal 500,000 — Unamortized discount (6,091) — Unamortized issuance costs (1,326) — Net carrying amount 492,583 — 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 $ 985,219 $ 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 can 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 six months ended June 30, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: Three Months Ended Six Months Ended 2021 2021 (In thousands) 2029 Notes Contractual interest expense $ 4,531 $ 5,651 Amortization of debt discount and issuance costs 168 217 Total interest expense - 2029 Notes 4,699 5,868 2031 Notes Contractual interest expense 4,844 6,041 Amortization of debt discount and issuance costs 127 164 Total interest expense - 2031 Notes 4,971 6,205 Total interest expense $ 9,670 $ 12,073 As of June 30, 2021, the Company was in compliance with all of its financial covenants under the Indenture. Convertible Senior Notes and Capped Call Transactions On May 18, 2021, the Company issued a notice of redemption for its Convertible Notes and as of June 30, 2021, redeemed all of the remaining outstanding $261.6 million aggregate principal amount of the Convertible Notes by issuing 3,688,584 shares of its Class A common stock and $52 thousand in cash. Of the $1.3 billion total value of these transactions, $1.0 billion and $255.6 million were allocated to the equity and liability components, respectively, utilizing an effective interest rate to determine the fair value of the liability component. The selected interest rate reflects the Company’s incremental borrowing rate, adjusted for the Company’s credit standing on nonconvertible debt with similar maturity. The extinguishment of these Convertible Notes resulted in a $21.4 million loss that is included in other (expenses) income, net, in the accompanying condensed consolidated statements of operations. The net carrying amount of the equity component of the Convertible Notes was as follows: As of As of June 30, December 31, 2021 2020 (In thousands) Proceeds allocated to the conversion options (debt discount) $ — $ 74,636 Issuance costs (2,819) (2,819) Net carrying amount $ (2,819) $ 71,817 The following table sets forth the interest expense recognized related to the Convertible Notes: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Contractual interest expense $ 106 $ 344 $ 276 $ 688 Amortization of debt issuance costs 69 484 328 968 Amortization of debt discount 1,287 5,694 4,315 11,388 Total interest expense $ 1,462 $ 6,522 $ 4,919 $ 13,044

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	6 Months Ended
	Jun. 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 13,391 $ 9,085 $ 12,046 $ 6,287 Additions 5,987 2,899 9,368 7,160 Write-offs (3,965) (1,736) (6,001) (3,199) Balance, end of period $ 15,413 $ 10,248 $ 15,413 $ 10,248 (b) Customer credit reserve: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 17,251 $ 9,687 $ 16,783 $ 6,784 Additions 11,919 13,376 27,385 21,550 Deductions against reserve (13,003) (11,532) (28,001) (16,803) Balance, end of period $ 16,167 $ 11,531 $ 16,167 $ 11,531

Revenue by Geographic Area

Revenue by Geographic Area	6 Months Ended
	Jun. 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 Six Months Ended 2021 2020 2021 2020 Revenue by geographic area: (In thousands) United States $ 452,912 $ 292,115 $ 874,443 $ 553,928 International 216,019 108,734 384,476 211,789 Total $ 668,931 $ 400,849 $ 1,258,919 $ 765,717 Percentage of revenue by geographic area: United States 68 % 73 % 69 % 72 % International 32 % 27 % 31 % 28 % Long-lived assets outside of the United States were not significant.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesLease and Other Commitments The Company 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 six months ended June 30, 2021, the Company entered into several such agreements with terms up to four years for a total purchase commitment of $11.1 million and $438.0 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 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 June 30, 2021, the Company has deferred $4.6 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. 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 June 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, one jurisdiction 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 believes that this assessment is incorrect and has disputed it, paid the full amount as required by law, and was seeking a refund or settlement. The payment made in excess of the accrued amount is reflected as a deposit in the Company’s accompanying condensed consolidated balance sheets. After failing to reach a settlement, on May 27, 2021, the Company filed a complaint challenging the jurisdiction’s assessment in court. 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 June 30, 2021 and December 31, 2020, the liability recorded for these taxes was $28.8 million and $25.6 million, respectively.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock As of June 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 June 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 June 30, 2021, 165,715,499 shares of Class A common stock and 10,218,422 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 had reserved shares of common stock for issuance as follows: As of As of June 30, December 31, 2021 2020 Stock options issued and outstanding 4,786,740 5,625,735 Unvested restricted stock units issued and outstanding 7,008,107 7,523,882 Class A common stock reserved for Twilio.org 663,061 707,265 Stock-based awards available for grant under 2016 Plan 25,833,950 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 44,773,507 45,310,099

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 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 June 30, 2021 and 2020, 100,107 and 190,642 shares of Class A common stock were purchased under the ESPP, respectively, and 106,054 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 Exercised (816,973) 39.06 Forfeited and canceled (271,864) 117.93 Outstanding options as of June 30, 2021 4,231,740 $ 68.62 6.43 $ 1,377,618 Options vested and exercisable as of June 30, 2021 2,573,689 $ 28.19 5.20 $ 941,885 Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 100,425 $ 338,031 $ 265,984 $ 406,390 Total estimated grant date fair value of options vested $ 45,873 $ 17,684 $ 77,852 $ 41,020 Weighted-average grant date fair value per share of options granted $ 200.05 $ 93.37 $ 202.36 $ 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 June 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 1,656,381 342.50 Vested (1,754,042) 90.57 Forfeited and canceled (418,114) 150.01 Unvested RSUs as of June 30, 2021 7,008,107 $ 190.79 $ 2,762,315 Additionally, as of June 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 $9.7 million. As of June 30, 2021, the Company had 258,554 shares of its Class A common stock in escrow that are subject to future vesting over a period of 2.3 years with a weighted average grant date fair value of $273.38 per share and aggregate intrinsic value of $101.9 million. As of June 30, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 203,631 2.4 Unvested restricted stock units and awards 1,217,788 3.1 Class A shares in escrow subject to future vesting 53,019 2.3 ESPP 7,150 0.4 Total $ 1,481,588 Valuation Assumptions 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 Six Months Ended Employee Stock Options: 2021 2020 2021 2020 Fair value of common stock $316.3 - $367.7 $108.4 - $191.9 $316.30 - $409.20 $108.4 - $191.9 Expected term (in years) 6.08 6.08 6.08 6.08 Expected volatility 59.7% 54.7% - 56.0% 58.3% - 59.7% 51.9% - 56.0% Risk-free interest rate 1.0% - 1.1% 0.4% 0.8% - 1.1% 0.4% - 1.4% Dividend rate —% —% —% —% Three Months Ended Six Months Ended Employee Stock Purchase Plan: 2021 2020 2021 2020 Expected term (in years) 0.50 0.50 0.5 0.5 Expected volatility 58.7% 72.1% 58.7% 72.1% Risk-free interest rate 0.04% 0.2% 0.04% 0.2% Dividend rate —% —% —% —% Stock-Based Compensation Expense The Company recorded total stock-based compensation expense as follows: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Cost of revenue $ 3,024 $ 2,143 $ 5,741 $ 3,980 Research and development 58,871 39,841 115,830 73,050 Sales and marketing 47,940 23,086 89,576 43,029 General and administrative 34,333 14,317 70,176 28,353 Total $ 144,168 $ 79,387 $ 281,323 $ 148,412

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic 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 Six Months Ended 2021 2020 2021 2020 Net loss attributable to common stockholders (in thousands) $ (227,853) $ (99,923) $ (434,395) $ (194,714) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 173,407,187 141,618,541 170,275,609 140,512,351 Net loss per share attributable to common stockholders, basic and diluted $ (1.31) $ (0.71) $ (2.55) $ (1.39) 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 June 30, 2021 2020 Stock options issued and outstanding 4,786,740 5,357,728 Restricted stock units issued and outstanding 7,008,107 8,791,928 Class A common stock reserved for Twilio.org 663,061 751,469 Class A common stock committed under ESPP 106,054 103,132 Convertible senior notes (1) — 4,331,844 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future 288,755 — Total 12,928,329 19,336,101 ____________________________________ (1) In the three months ended June 30, 2021, the remaining principal amount of the Convertible Notes was fully redeemed and as of June 30, 2021, no Convertible Notes were outstanding. Refer to Note 10 for further detail on the redemption of these notes. As of June 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 June 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 Taxes

Income Taxes	6 Months Ended
	Jun. 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 provision of $1.3 million and $2.2 million for the three and six months ended June 30, 2021, respectively, and $0.3 million and $1.3 million for the three and six months ended June 30, 2020, respectively. The provision for income taxes recorded in the three and six months ended June 30, 2021 and 2020 consists primarily of income taxes and withholding taxes in foreign jurisdictions in which the Company conducts business, partially offset by an income tax benefit from the reversal of U.S. deferred tax liabilities related to acquired intangibles from prior year business combinations. The primary difference between the effective tax rate and the federal statutory rate is the full valuation allowance the Company established on the federal, state, and certain foreign net operating losses and credits. The Company continues to maintain a full valuation allowance against its U.S. federal and state net deferred tax assets.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsOn July 14, 2021, the Company acquired Zipwhip, Inc. (“Zipwhip”), a trusted partner to carriers and a leading provider of toll-free messaging in the United States, for an aggregate consideration of $850.0 million, subject to certain exceptions and adjustments, in the form of shares of Class A common stock of the Company or cash, as provided by the Agreement and Plan of Merger and Reorganization dated May 16, 2021 (the "Merger Agreement"). Part of the cash consideration was paid to settle the vested stock options and restricted stock units of Zipwhip that were outstanding on the acquisition closing date. The Company assumed all unvested and outstanding stock options and restricted stock units of Zipwhip continuing employees as converted into its own respective equity awards at the conversion ratio provided in the Merger Agreement. During the six months ended June 30, 2021, the Company incurred $2.5 million in expenses related to this transaction.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 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 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, 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)	6 Months Ended
	Jun. 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 $ 1,191,640 $ — $ — $ 1,191,640 $ — $ — $ 1,191,640 Commercial paper 177,609 — — — 177,609 — 177,609 Total included in cash and cash equivalents 1,369,249 — — 1,191,640 177,609 — 1,369,249 Marketable securities: U.S. Treasury securities 415,676 125 (434) 415,367 — — 415,367 Non-U.S. Government securities 237,875 2 (264) 237,613 — — 237,613 Corporate debt securities and commercial paper 3,468,815 5,206 (1,418) 47,000 3,425,603 — 3,472,603 Total marketable securities 4,122,366 5,333 (2,116) 699,980 3,425,603 — 4,125,583 Total financial assets $ 5,491,615 $ 5,333 $ (2,116) $ 1,891,620 $ 3,603,212 $ — $ 5,494,832 Financial Liabilities: Accrued expenses and other current liabilities: Foreign currency derivative liabilities $ — $ — $ (2,908) $ — $ (2,908) $ — $ (2,908) Total financial liabilities $ — $ — $ (2,908) $ — $ (2,908) $ — $ (2,908) 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 June 30, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,375,453 $ 1,377,906 $ 1,126,091 $ 1,128,927 One to three years 2,746,913 2,747,677 971,413 976,979 Total $ 4,122,366 $ 4,125,583 $ 2,097,504 $ 2,105,906

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Jun. 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 Six Months Ended 2021 2021 (In thousands) Losses recognized in OCI Net change in market value of effective foreign currency forward exchange contracts $ (2,908) $ (2,908) Losses recognized in income (effective portion) Cost of revenue $ (467) $ (467)

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment consisted of the following: As of As of June 30, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 169,887 $ 142,489 Data center equipment (1) 52,460 43,477 Leasehold improvements 73,229 69,756 Office equipment 50,902 35,346 Furniture and fixtures (1) 13,769 12,312 Software 10,235 9,943 Total property and equipment 370,482 313,323 Less: accumulated depreciation and amortization (164,128) (130,084) Total property and equipment, net $ 206,354 $ 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Depreciation and amortization expense $ 14,247 $ 11,912 $ 28,652 $ 23,831 Capitalized internal-use software development costs $ 16,493 $ 12,593 $ 31,528 $ 24,565 Stock based compensation costs included in capitalized internal-use software development costs $ 5,089 $ 3,597 $ 9,740 $ 7,015 Amortization of capitalized internal-use software development costs $ 4,319 $ 4,421 $ 8,851 $ 9,010

Right-of-Use Asset and Lease _2

Right-of-Use Asset and Lease Liabilities (Tables)	6 Months Ended
	Jun. 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Operating lease cost $ 14,505 $ 12,497 $ 29,378 $ 22,921 Finance lease cost: Amortization of assets 2,804 1,830 5,484 3,734 Interest on lease liabilities 260 194 523 392 Short-term lease cost 846 1,091 2,538 2,503 Variable lease cost 2,033 1,884 4,933 3,180 Total net lease cost $ 20,448 $ 17,496 $ 42,856 $ 32,730 Supplemental cash flow and other information related to leases was as follows: Six Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 29,233 $ 22,199 Operating cash flows from finance leases (interest) $ 523 $ 392 Financing cash flows from finance leases $ 5,503 $ 3,718 Weighted average remaining lease term (in years): Operating leases 5.7 5.8 Finance leases 3.2 3.2 Weighted average discount rate: Operating leases 4.8 % 5.4 % Finance leases 3.6 % 4.8 %
Assets and Liabilities, Lessee	Supplemental balance sheet information related to leases was as follows: As of As of June 30, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 233,449 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 25,553 25,771 Total leased assets $ 259,002 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,760 $ 48,338 Finance Finance lease liability, current 8,877 9,062 Noncurrent Operating Operating lease liability, noncurrent 205,997 229,905 Finance Finance lease liability, noncurrent 17,804 17,856 Total lease liabilities $ 279,438 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $75.9 million and $57.1 million as of June 30, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $20.5 million and $15.0 million as of June 30, 2021 and December 31, 2020, respectively.
Lessee, Operating Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of June 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining six months) $ 28,031 $ 5,012 2022 58,023 8,987 2023 50,259 8,240 2024 45,716 4,999 2025 32,464 547 Thereafter 75,332 516 Total lease payments 289,825 28,301 Less: imputed interest (37,068) (1,620) Total lease obligations 252,757 26,681 Less: current obligations (46,760) (8,877) Long-term lease obligations $ 205,997 $ 17,804
Finance Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of June 30, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining six months) $ 28,031 $ 5,012 2022 58,023 8,987 2023 50,259 8,240 2024 45,716 4,999 2025 32,464 547 Thereafter 75,332 516 Total lease payments 289,825 28,301 Less: imputed interest (37,068) (1,620) Total lease obligations 252,757 26,681 Less: current obligations (46,760) (8,877) Long-term lease obligations $ 205,997 $ 17,804

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill balance	The Goodwill balance as of June 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 68,791 Balance as of June 30, 2021 $ 4,664,185
Schedule of intangible assets	Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 738,031 $ (165,502) $ 572,529 Customer relationships 390,564 (89,466) 301,098 Supplier relationships 12,071 (3,815) 8,256 Trade names 30,269 (10,544) 19,725 Order backlog 10,000 (6,667) 3,333 Patent 3,594 (442) 3,152 Total amortizable intangible assets 1,184,529 (276,436) 908,093 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,189,744 $ (276,436) $ 913,308 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 six months) $ 92,810 2022 173,946 2023 170,636 2024 165,062 2025 161,531 Thereafter 144,108 Total $ 908,093

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	6 Months Ended
	Jun. 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 June 30, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 63,154 $ 54,683 Accrued bonus and commission 29,319 25,341 Accrued cost of revenue 96,959 80,620 Sales and other taxes payable 55,914 48,390 ESPP contributions 7,605 6,272 Finance lease liability, current 8,877 9,062 Accrued other expense 69,976 28,527 Total accrued expenses and other current liabilities $ 331,804 $ 252,895
Schedule of other long-term liabilities	Other long-term liabilities consisted of the following: As of As of June 30, December 31, 2021 2020 (In thousands) Deferred tax liability $ 19,380 $ 13,684 Acquisition holdback 10,623 8,800 Accrued other expenses 17,165 14,149 Total other long-term liabilities $ 47,168 $ 36,633

Notes Payable (Tables)

Notes Payable (Tables)	6 Months Ended
	Jun. 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 June 30, December 31, 2021 2020 (In thousands) 2029 and 2031 Senior Notes 2029 Senior Notes Principal $ 500,000 $ — Unamortized discount (6,041) — Unamortized issuance costs (1,323) — Net carrying amount 492,636 — 2031 Senior Notes Principal 500,000 — Unamortized discount (6,091) — Unamortized issuance costs (1,326) — Net carrying amount 492,583 — 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 $ 985,219 $ 302,068 The net carrying amount of the equity component of the Convertible Notes was as follows: As of As of June 30, December 31, 2021 2020 (In thousands) Proceeds allocated to the conversion options (debt discount) $ — $ 74,636 Issuance costs (2,819) (2,819) Net carrying amount $ (2,819) $ 71,817
Schedule of interest expense recognized related to the Notes	For the three and six months ended June 30, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: Three Months Ended Six Months Ended 2021 2021 (In thousands) 2029 Notes Contractual interest expense $ 4,531 $ 5,651 Amortization of debt discount and issuance costs 168 217 Total interest expense - 2029 Notes 4,699 5,868 2031 Notes Contractual interest expense 4,844 6,041 Amortization of debt discount and issuance costs 127 164 Total interest expense - 2031 Notes 4,971 6,205 Total interest expense $ 9,670 $ 12,073 The following table sets forth the interest expense recognized related to the Convertible Notes: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Contractual interest expense $ 106 $ 344 $ 276 $ 688 Amortization of debt issuance costs 69 484 328 968 Amortization of debt discount 1,287 5,694 4,315 11,388 Total interest expense $ 1,462 $ 6,522 $ 4,919 $ 13,044

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
Schedule of the allowance for doubtful accounts	Allowance for doubtful accounts: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 13,391 $ 9,085 $ 12,046 $ 6,287 Additions 5,987 2,899 9,368 7,160 Write-offs (3,965) (1,736) (6,001) (3,199) Balance, end of period $ 15,413 $ 10,248 $ 15,413 $ 10,248
Schedule of the sales credit reserve	Customer credit reserve: Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands) Balance, beginning of period $ 17,251 $ 9,687 $ 16,783 $ 6,784 Additions 11,919 13,376 27,385 21,550 Deductions against reserve (13,003) (11,532) (28,001) (16,803) Balance, end of period $ 16,167 $ 11,531 $ 16,167 $ 11,531

Revenue by Geographic Area (Tab

Revenue by Geographic Area (Tables)	6 Months Ended
	Jun. 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 Six Months Ended 2021 2020 2021 2020 Revenue by geographic area: (In thousands) United States $ 452,912 $ 292,115 $ 874,443 $ 553,928 International 216,019 108,734 384,476 211,789 Total $ 668,931 $ 400,849 $ 1,258,919 $ 765,717 Percentage of revenue by geographic area: United States 68 % 73 % 69 % 72 % International 32 % 27 % 31 % 28 %

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Schedule of reserved shares of common stock for issuance	The Company had reserved shares of common stock for issuance as follows: As of As of June 30, December 31, 2021 2020 Stock options issued and outstanding 4,786,740 5,625,735 Unvested restricted stock units issued and outstanding 7,008,107 7,523,882 Class A common stock reserved for Twilio.org 663,061 707,265 Stock-based awards available for grant under 2016 Plan 25,833,950 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 44,773,507 45,310,099

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 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 Exercised (816,973) 39.06 Forfeited and canceled (271,864) 117.93 Outstanding options as of June 30, 2021 4,231,740 $ 68.62 6.43 $ 1,377,618 Options vested and exercisable as of June 30, 2021 2,573,689 $ 28.19 5.20 $ 941,885
Schedule of weighted average grant date fair value	Three Months Ended Six Months Ended 2021 2020 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 100,425 $ 338,031 $ 265,984 $ 406,390 Total estimated grant date fair value of options vested $ 45,873 $ 17,684 $ 77,852 $ 41,020 Weighted-average grant date fair value per share of options granted $ 200.05 $ 93.37 $ 202.36 $ 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 1,656,381 342.50 Vested (1,754,042) 90.57 Forfeited and canceled (418,114) 150.01 Unvested RSUs as of June 30, 2021 7,008,107 $ 190.79 $ 2,762,315
Schedule of unrecognized compensation	As of June 30, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 203,631 2.4 Unvested restricted stock units and awards 1,217,788 3.1 Class A shares in escrow subject to future vesting 53,019 2.3 ESPP 7,150 0.4 Total $ 1,481,588
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 Six Months Ended Employee Stock Options: 2021 2020 2021 2020 Fair value of common stock $316.3 - $367.7 $108.4 - $191.9 $316.30 - $409.20 $108.4 - $191.9 Expected term (in years) 6.08 6.08 6.08 6.08 Expected volatility 59.7% 54.7% - 56.0% 58.3% - 59.7% 51.9% - 56.0% Risk-free interest rate 1.0% - 1.1% 0.4% 0.8% - 1.1% 0.4% - 1.4% Dividend rate —% —% —% —% Three Months Ended Six Months Ended Employee Stock Purchase Plan: 2021 2020 2021 2020 Expected term (in years) 0.50 0.50 0.5 0.5 Expected volatility 58.7% 72.1% 58.7% 72.1% Risk-free interest rate 0.04% 0.2% 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 Six Months Ended 2021 2020 2021 2020 (In thousands) Cost of revenue $ 3,024 $ 2,143 $ 5,741 $ 3,980 Research and development 58,871 39,841 115,830 73,050 Sales and marketing 47,940 23,086 89,576 43,029 General and administrative 34,333 14,317 70,176 28,353 Total $ 144,168 $ 79,387 $ 281,323 $ 148,412

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	6 Months Ended
	Jun. 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 Six Months Ended 2021 2020 2021 2020 Net loss attributable to common stockholders (in thousands) $ (227,853) $ (99,923) $ (434,395) $ (194,714) Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted 173,407,187 141,618,541 170,275,609 140,512,351 Net loss per share attributable to common stockholders, basic and diluted $ (1.31) $ (0.71) $ (2.55) $ (1.39)
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 June 30, 2021 2020 Stock options issued and outstanding 4,786,740 5,357,728 Restricted stock units issued and outstanding 7,008,107 8,791,928 Class A common stock reserved for Twilio.org 663,061 751,469 Class A common stock committed under ESPP 106,054 103,132 Convertible senior notes (1) — 4,331,844 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future 288,755 — Total 12,928,329 19,336,101 ____________________________________ (1) In the three months ended June 30, 2021, the remaining principal amount of the Convertible Notes was fully redeemed and as of June 30, 2021, no Convertible Notes were outstanding. Refer to Note 10 for further detail on the redemption of these notes. As of June 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 June 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

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial Assets:
Cash and cash equivalents:	$ 1,369,249	$ 658,749
Amortized Cost or Carrying Value	4,122,366	2,097,504
Gross Unrealized Gains	5,333	8,538
Gross Unrealized Losses	(2,116)	(136)
Marketable securities, aggregate fair value	4,125,583	2,105,906
Total financial assets	5,491,615	2,756,253
Total financial assets	5,494,832	2,764,655
Fair Value Measurements, Liabilities
Gross Unrealized Losses	(2,908)
Total financial liabilities	(2,908)
Foreign Currency Derivative
Fair Value Measurements, Liabilities
Derivative liabilities	(2,908)
U.S. Treasury securities
Financial Assets:
Amortized Cost or Carrying Value	415,676	223,247
Gross Unrealized Gains	125	389
Gross Unrealized Losses	(434)	(1)
Marketable securities, aggregate fair value	415,367	223,635
Non-U.S. Government securities
Financial Assets:
Amortized Cost or Carrying Value	237,875
Gross Unrealized Gains	2
Gross Unrealized Losses	(264)
Marketable securities, aggregate fair value	237,613
Corporate debt securities and commercial paper
Financial Assets:
Amortized Cost or Carrying Value	3,468,815	1,874,257
Gross Unrealized Gains	5,206	8,149
Gross Unrealized Losses	(1,418)	(135)
Marketable securities, aggregate fair value	3,472,603	1,882,271
Level 1
Financial Assets:
Cash and cash equivalents:	1,191,640	656,749
Marketable securities, aggregate fair value	699,980	273,635
Total financial assets	1,891,620	930,384
Fair Value Measurements, Liabilities
Total financial liabilities	0
Level 1 | Foreign Currency Derivative
Fair Value Measurements, Liabilities
Derivative liabilities	0
Level 1 | U.S. Treasury securities
Financial Assets:
Marketable securities, aggregate fair value	415,367	223,635
Level 1 | Non-U.S. Government securities
Financial Assets:
Marketable securities, aggregate fair value	237,613
Level 1 | Corporate debt securities and commercial paper
Financial Assets:
Marketable securities, aggregate fair value	47,000	50,000
Level 2
Financial Assets:
Cash and cash equivalents:	177,609	2,000
Marketable securities, aggregate fair value	3,425,603	1,832,271
Total financial assets	3,603,212	1,834,271
Fair Value Measurements, Liabilities
Total financial liabilities	(2,908)
Level 2 | Foreign Currency Derivative
Fair Value Measurements, Liabilities
Derivative liabilities	(2,908)
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	3,425,603	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
Derivative 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:	1,191,640	656,749
Carrying Value | Commercial paper
Financial Assets:
Cash and cash equivalents:	177,609	2,000
Aggregate Fair Value | Money market funds
Financial Assets:
Cash and cash equivalents:	1,191,640	656,749
Aggregate Fair Value | Commercial paper
Financial Assets:
Cash and cash equivalents:	177,609	2,000
Aggregate Fair Value | Level 1 | Money market funds
Financial Assets:
Cash and cash equivalents:	1,191,640	656,749
Aggregate Fair Value | Level 2 | Commercial paper
Financial Assets:
Cash and cash equivalents:	$ 177,609	$ 2,000

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest earned on marketable securities	$ 5,600,000	$ 7,800,000	$ 9,400,000	$ 16,600,000
Note receivable	12,300,000		12,300,000			$ 9,300,000
Impairment of long-lived assets	0	$ 0	0	$ 0
Senior Notes 3.625 Percent Due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)					3.625%
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	518,200,000		518,200,000
Senior Notes 3.875 Percent Due 2031
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)					3.875%
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	$ 521,700,000		$ 521,700,000

Fair Value Measurements - Contr

Fair Value Measurements - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Less than one year, amortized cost	$ 1,375,453	$ 1,126,091
One to three years, amortized cost	2,746,913	971,413
Amortized Cost or Carrying Value	4,122,366	2,097,504
Less than one year, aggregate fair value	1,377,906	1,128,927
One to three years, aggregate fair value	2,747,677	976,979
Total aggregate fair value	$ 4,125,583	$ 2,105,906

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative liabilities	$ 2.9
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	$ 110
Foreign Currency Forward | Designated as Cash Flow Hedges | Sell | Cash Flow Hedge
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, notional amount	$ 133.9

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	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Foreign Currency Fair Value Hedge Derivative [Line Items]
Losses recognized in OCI	$ (2,908)	$ (2,908)
Cost of revenue
Foreign Currency Fair Value Hedge Derivative [Line Items]
Losses recognized in income (effective portion)	$ (467)	$ (467)

Property and Equipment - Proper

Property and Equipment - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property and Equipment
Total property and equipment	$ 370,482	$ 313,323
Less: accumulated depreciation and amortization	(164,128)	(130,084)
Total property and equipment, net	206,354	183,239
Capitalized internal-use software development costs
Property and Equipment
Total property and equipment	169,887	142,489
Data center equipment
Property and Equipment
Total property and equipment	52,460	43,477
Leasehold improvements
Property and Equipment
Total property and equipment	73,229	69,756
Office equipment
Property and Equipment
Total property and equipment	50,902	35,346
Furniture and fixtures
Property and Equipment
Total property and equipment	13,769	12,312
Software
Property and Equipment
Total property and equipment	$ 10,235	$ 9,943

Property and Equipment - Schedu

Property and Equipment - Schedule of Supplemental Depreciation and Amortization Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 14,247	$ 11,912	$ 28,652	$ 23,831
Capitalized internal use software development costs	16,493	12,593	31,528	24,565
Stock-based compensation capitalized in software development costs	5,089	3,597	9,740	7,015
Amortization of capitalized software development costs	$ 4,319	$ 4,421	$ 8,851	$ 9,010

Right-of-Use Asset and Lease _3

Right-of-Use Asset and Lease Liabilities - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)property
Lessee, Lease, Description [Line Items]
Number of leased properties | property	27
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	$ 5.1
Finance lease not yet commenced, term of contract	4 years
Minimum
Lessee, Lease, Description [Line Items]
Term of lease	4 months 24 days
Maximum
Lessee, Lease, Description [Line Items]
Term of lease	7 years 9 months 18 days

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating lease cost	$ 14,505	$ 12,497	$ 29,378	$ 22,921
Finance lease cost:
Amortization of assets	2,804	1,830	5,484	3,734
Interest on lease liabilities	260	194	523	392
Short-term lease cost	846	1,091	2,538	2,503
Variable lease cost	2,033	1,884	4,933	3,180
Total net lease cost	$ 20,448	$ 17,496	$ 42,856	$ 32,730

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	Jun. 30, 2021	Dec. 31, 2020
ASSETS
Operating lease assets	$ 233,449	$ 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	$ 25,553	$ 25,771
Total leased assets	259,002	284,381
Current liabilities:
Operating	46,760	48,338
Finance	8,877	9,062
Noncurrent liabilities
Operating	205,997	229,905
Finance	17,804	17,856
Total lease liabilities	279,438	305,161
Operating lease accumulated amortization	75,900	57,100
Finance lease accumulated depreciation	$ 20,500	$ 15,000

Right-of-Use Asset and Lease _6

Right-of-Use Asset and Lease Liabilities - Supplemental Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 29,233	$ 22,199
Operating cash flows from finance leases (interest)	523	392
Financing cash flows from finance leases	$ 5,503	$ 3,718
Weighted average remaining lease term (in years):
Operating leases	5 years 8 months 12 days		5 years 9 months 18 days
Finance leases	3 years 2 months 12 days		3 years 2 months 12 days
Weighted average discount rate:
Operating leases (as a percent)	4.80%		5.40%
Finance leases (as a percent)	3.60%		4.80%

Right-of-Use Asset and Lease _7

Right-of-Use Asset and Lease Liabilities - Lease Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Maturity Of Operating Lease Liabilities
2021 (remaining six months)	$ 28,031
2022	58,023
2023	50,259
2024	45,716
2025	32,464
Thereafter	75,332
Total lease payments	289,825
Less: imputed interest	(37,068)
Total lease obligations	252,757
Less: current obligations	(46,760)	$ (48,338)
Long-term lease obligations	205,997	229,905
Maturity Of Finance Lease Liabilities
2021 (remaining six months)	5,012
2022	8,987
2023	8,240
2024	4,999
2025	547
Thereafter	516
Total lease payments	28,301
Less: imputed interest	(1,620)
Total lease obligations	26,681
Less: current obligations	(8,877)	(9,062)
Long-term lease obligations	$ 17,804	$ 17,856

Business Combinations (Details)

Business Combinations (Details) - Ionic - USD ($) $ in Millions	Apr. 09, 2021	Jun. 30, 2021
Acquisition
Payments to acquire businesses, gross	$ 30.2
Acquisition related costs		$ 1.1

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill Rollforward (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Goodwill
Balance (beginning of period)	$ 4,595,394
Goodwill additions and adjustments	68,791
Balance (end of period)	$ 4,664,185

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Amortizable intangible assets:
Gross	$ 1,184,529	$ 1,147,219
Accumulated Amortization	(276,436)	(185,861)
Net	908,093	961,358
Intangible assets, gross	1,189,744	1,152,434
Total	913,308	966,573
Trademark and tradename
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	738,031	724,599
Accumulated Amortization	(165,502)	(113,282)
Net	572,529	611,317
Customer relationships
Amortizable intangible assets:
Gross	390,564	379,344
Accumulated Amortization	(89,466)	(59,574)
Net	301,098	319,770
Supplier relationships
Amortizable intangible assets:
Gross	12,071	4,356
Accumulated Amortization	(3,815)	(3,044)
Net	8,256	1,312
Trade names
Amortizable intangible assets:
Gross	30,269	25,560
Accumulated Amortization	(10,544)	(7,921)
Net	19,725	17,639
Order backlog
Amortizable intangible assets:
Gross	10,000	10,000
Accumulated Amortization	(6,667)	(1,667)
Net	3,333	8,333
Patent
Amortizable intangible assets:
Gross	3,594	3,360
Accumulated Amortization	(442)	(373)
Net	$ 3,152	$ 2,987

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 45.4	$ 20.6	$ 90.6	$ 40.9

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Total Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Intangible Assets
2021 (remaining six months)	$ 92,810
2022	173,946
2023	170,636
2024	165,062
2025	161,531
Thereafter	144,108
Net	$ 908,093	$ 961,358

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Accrued payroll and related	$ 63,154	$ 54,683
Accrued bonus and commission	29,319	25,341
Accrued cost of revenue	96,959	80,620
Sales and other taxes payable	55,914	48,390
ESPP contributions	7,605	6,272
Finance lease liability, current	8,877	9,062
Accrued other expense	69,976	28,527
Total accrued expenses and other current liabilities	$ 331,804	$ 252,895

Accrued Expenses and Other Li_4

Accrued Expenses and Other Liabilities - Long-term Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Deferred tax liability	$ 19,380	$ 13,684
Acquisition holdback	10,623	8,800
Accrued other expenses	17,165	14,149
Total other long-term liabilities	$ 47,168	$ 36,633

Notes Payable - Summary of Long

Notes Payable - Summary of Long-Term Debt (Details) - USD ($)	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Net carrying amount	$ 985,219,000		$ 302,068,000
Senior Notes 3.625 Percent Due 2029
Debt Instrument [Line Items]
Principal	500,000,000	$ 500,000,000	0
Unamortized discount	(6,041,000)		0
Unamortized issuance costs	(1,323,000)		0
Net carrying amount	492,636,000		0
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Principal	500,000,000	$ 500,000,000	0
Unamortized discount	(6,091,000)		0
Unamortized issuance costs	(1,326,000)		0
Net carrying amount	492,583,000		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	Jun. 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%
Convertible senior notes due 2023
Debt Instrument [Line Items]
Principal		$ 0	$ 343,702,000

Notes Payable - Terms (Details)

Notes Payable - Terms (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Carrying amount of equity component	$ 1,000,000		$ 1,000,000
Payment for debt settlement			52
Debt conversion, converted instrument, amount including cash			1,300,000
Debt instrument, liability component	$ 255,600		255,600
(Loss) gain on extinguishment of debt			(28,986)	$ 0
Proceeds from settlement of capped call, net of settlement costs			$ 228,412	$ 0
Common Stock Class A | Common Stock
Debt Instrument [Line Items]
Equity component from partial settlement of 2023 convertible senior notes (in shares)	3,688,584	1,158,381	3,688,584
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 | Minimum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			100.00%
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 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%
Convertible senior notes due 2023
Debt Instrument [Line Items]
Carrying amount of equity component	$ 0		$ 0		$ 74,636
Debt settlement, amount			261,600
(Loss) gain on extinguishment of debt			(21,400)
Capped Call Arrangement
Debt Instrument [Line Items]
(Loss) gain on extinguishment of debt			3,200
Proceeds from settlement of capped call, net of settlement costs			229,800
Transaction costs for settlement of capped calls			$ 1,400

Notes Payable - Net Carrying Am

Notes Payable - Net Carrying Amount (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Proceeds allocated to the conversion options (debt discount)	$ 1,000,000		$ 1,000,000
Issuance costs	(50)	$ (727)
Convertible senior notes due 2023
Debt Instrument [Line Items]
Proceeds allocated to the conversion options (debt discount)	0		0	$ 74,636
Issuance costs			(2,819)	(2,819)
Net carrying amount	$ (2,819)		$ (2,819)	$ 71,817

Notes Payable - Interest Expens

Notes Payable - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest expense recognized related to the Notes
Amortization of debt discount and issuance costs			$ 5,081	$ 12,356
Total interest expense	$ 9,670		12,073
Senior Notes 3.625 Percent Due 2029
Interest expense recognized related to the Notes
Contractual interest expense	4,531		5,651
Amortization of debt discount	168		217
Total interest expense	4,699		5,868
Senior Notes 3.875 Percent Due 2031
Interest expense recognized related to the Notes
Contractual interest expense	4,844		6,041
Amortization of debt discount	127		164
Total interest expense	4,971		6,205
Convertible senior notes due 2023
Interest expense recognized related to the Notes
Contractual interest expense	106	$ 344	276	688
Amortization of debt discount and issuance costs	69	484	328	968
Amortization of debt discount	1,287	5,694	4,315	11,388
Total interest expense	$ 1,462	$ 6,522	$ 4,919	$ 13,044

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allowance for doubtful accounts
Balance, beginning of period	$ 13,391	$ 9,085	$ 12,046	$ 6,287
Additions	5,987	2,899	9,368	7,160
Write-offs	(3,965)	(1,736)	(6,001)	(3,199)
Balance, end of period	$ 15,413	$ 10,248	$ 15,413	$ 10,248

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Sales Credit Reserve (Details) - Sales credit reserve - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Sales credit reserve
Balance, beginning of period	$ 17,251	$ 9,687	$ 16,783	$ 6,784
Additions	11,919	13,376	27,385	21,550
Deductions against reserve	(13,003)	(11,532)	(28,001)	(16,803)
Balance, end of period	$ 16,167	$ 11,531	$ 16,167	$ 11,531

Revenue by Geographic Area - Re

Revenue by Geographic Area - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue by geographic area:
Revenue	$ 668,931	$ 400,849	$ 1,258,919	$ 765,717
United States
Revenue by geographic area:
Revenue	452,912	292,115	874,443	553,928
International
Revenue by geographic area:
Revenue	$ 216,019	$ 108,734	$ 384,476	$ 211,789

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
United States
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	68.00%	73.00%	69.00%	72.00%
International
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	32.00%	27.00%	31.00%	28.00%

Commitments and Contingencies -

Commitments and Contingencies - Other Commitments (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
	Feb. 28, 2021	Jun. 30, 2021	Jun. 30, 2020
Long-term Purchase Commitment [Line Items]
Term of non-cancelable agreement		4 years
Purchase commitment		$ 11,100	$ 438,000
Payments to acquire investments		2,807,798	$ 443,816
Syniverse
Long-term Purchase Commitment [Line Items]
Payments to acquire investments	$ 750,000
Deferred costs		$ 4,600
Minimum
Long-term Purchase Commitment [Line Items]
Term of non-cancelable lease		1 year
Maximum
Long-term Purchase Commitment [Line Items]
Term of non-cancelable lease		8 years

Commitments and Contingencies_2

Commitments and Contingencies - Indemnification Agreements (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Indemnification Agreements
Loss Contingencies [Line Items]
Amount accrued	$ 0	$ 0

Commitments and Contingencies_3

Commitments and Contingencies - Other taxes (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Taxes payable, jurisdictional estimate	$ 38.8
Accrued taxes	11.5
Liability for uncertain tax positions	$ 28.8	$ 25.6

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) - $ / shares	Jun. 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)	Jun. 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)	165,715,499	153,496,222
Common stock, outstanding (in shares)	165,715,499	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)	10,218,422	10,551,302
Common stock, outstanding (in shares)	10,218,422	10,551,302
Votes per share | vote	10

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Shares Reserved (Details) - shares	Jun. 30, 2021	Dec. 31, 2020
Stockholders' Equity
Total (in shares)	44,773,507	45,310,099
2016 Stock Option and Incentive Plan
Stockholders' Equity
Stock-based awards available for grant under 2016 Plan (in shares)	25,833,950	18,942,205
Common Stock Class A
Stockholders' Equity
Class A common stock reserved for Twilio.org (in shares)	663,061	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)	4,786,740	5,625,735
Restricted stock units issued and outstanding
Stockholders' Equity
Unvested restricted stock units and awards issued and outstanding (in shares)	7,008,107	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	Jun. 30, 2021	Jun. 30, 2020	Jun. 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)					4 months 24 days
Class A common stock committed under ESPP | Common Stock
Stock Based Compensation
Shares purchased in period (in shares)			100,107	190,642
Class A common stock committed under ESPP | Common Stock | Forecast
Stock Based Compensation
Shares purchased in period (in shares)		106,054
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			$ 9.7		$ 9.7
Class A shares in escrow subject to future vesting
Stock Based Compensation
Outstanding RSUs, aggregate intrinsic value			$ 101.9		$ 101.9
Shares subject to future vesting conditions (in shares)					258,554
Weighted-average period (in years)					2 years 3 months 18 days
Shares subject to future vesting conditions, weighted average grant date fair value (in dollars per share)					$ 273.38
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	6 Months Ended	12 Months Ended
	Jun. 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
Exercised (in shares) | shares	(816,973)
Forfeited and cancelled (in shares) | shares	(271,864)
Outstanding options as of the end of the period (in shares) | shares	4,231,740	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
Exercised (in dollars per share) | $ / shares	39.06
Forfeited and cancelled (in dollars per share) | $ / shares	117.93
Outstanding options as of the end of the period (in dollars per share) | $ / shares	$ 68.62	$ 51.71
Weighted- average remaining contractual term (In years)
Weighted-average remaining contractual term (in years)	6 years 5 months 4 days	6 years 10 months 6 days
Aggregate intrinsic value | $	$ 1,377,618	$ 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	2,573,689
Options vested and exercisable - weighted-average exercise price (in dollars per share) | $ / shares	$ 28.19
Options vested and exercisable - weighted-average remaining contractual term	5 years 2 months 12 days
Options vested and exercisable - aggregate intrinsic value | $	$ 941,885

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock Based Compensation
Aggregate intrinsic value of stock options exercised	$ 100,425	$ 338,031	$ 265,984	$ 406,390
Total estimated grant date fair value of options vested	$ 45,873	$ 17,684	$ 77,852	$ 41,020
Weighted-average grant date fair value per share of options granted (in dollars per share)	$ 200.05	$ 93.37	$ 202.36	$ 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	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Number of awards outstanding
Nonvested RSUs at the beginning of the period (in shares)	7,523,882
Granted (in shares)	1,656,381
Vested (in shares)	(1,754,042)
Forfeited and canceled (in shares)	(418,114)
Nonvested RSUs at the end of the period (in shares)	7,008,107
Weighted- average grant date fair value (Per share)
Nonvested RSUs at the beginning of the period (in dollars per share)	$ 131.76
Granted (in dollars per share)	342.50
Vested (in dollars per share)	90.57
Forfeited and canceled (in dollars per share)	150.01
Nonvested RSUs at the end of the period (in dollars per share)	$ 190.79
Aggregate intrinsic value (In thousands)
Aggregate intrinsic value	$ 2,762,315	$ 2,542,858

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Units - Unrecognized Compensation Cost (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Stock Based Compensation
Total	$ 1,481,588
Unvested stock options
Stock Based Compensation
Unvested stock options	$ 203,631
Weighted-average period (in years)	2 years 4 months 24 days
Unvested restricted stock units and awards
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 1,217,788
Weighted-average period (in years)	3 years 1 month 6 days
Class A shares in escrow subject to future vesting
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 53,019
Weighted-average period (in years)	2 years 3 months 18 days
ESPP
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 7,150
Weighted-average period (in years)	4 months 24 days

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee stock options
Valuation Assumptions
Expected term (in years)	6 years 29 days	6 years 29 days	6 years 29 days	6 years 29 days
Expected volatility, low end of range (as a percent)	59.70%	54.70%	58.30%	51.90%
Expected volatility, high end of range (as a percent)		56.00%	59.70%	56.00%
Risk-free interest rate (as a percent)		0.40%
Risk-free interest rate, low end of range (as a percent)	1.00%		0.80%	0.40%
Risk-free interest rate, high end of range (as a percent)	1.10%		1.10%	1.40%
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	6 months	6 months
Expected volatility (as a percent)	58.70%	72.10%	58.70%	72.10%
Risk-free interest rate (as a percent)	0.04%	0.20%	0.04%	0.20%
Dividend rate (as a percent)	0.00%	0.00%	0.00%	0.00%
Minimum | Employee stock options
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 316.3	$ 108.4	$ 316.30	$ 108.4
Maximum | Employee stock options
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 367.7	$ 191.9	$ 409.20	$ 191.9

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation Expense
Stock-based compensation expense	$ 144,168	$ 79,387	$ 281,323	$ 148,412
Cost of revenue
Stock-Based Compensation Expense
Stock-based compensation expense	3,024	2,143	5,741	3,980
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense	58,871	39,841	115,830	73,050
Sales and marketing
Stock-Based Compensation Expense
Stock-based compensation expense	47,940	23,086	89,576	43,029
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense	$ 34,333	$ 14,317	$ 70,176	$ 28,353

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Loss Per Share Attributable to Common Stockholders
Net loss attributable to common stockholders, basic	$ (227,853)	$ (99,923)	$ (434,395)	$ (194,714)
Net loss attributable to common stockholders, diluted	$ (227,853)	$ (99,923)	$ (434,395)	$ (194,714)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic (in shares)	173,407,187	141,618,541	170,275,609	140,512,351
Weighted-average shares used to compute net loss per share attributable to common stockholders, diluted (in shares)	173,407,187	141,618,541	170,275,609	140,512,351
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (1.31)	$ (0.71)	$ (2.55)	$ (1.39)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (1.31)	$ (0.71)	$ (2.55)	$ (1.39)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Anti-Dilutive Securities (Details) - $ / shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Anti-dilutive securities
Antidilutive securities (in shares)	12,928,329	19,336,101
Conversion price (in dollars per share)	$ 70.90
Stock options issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	4,786,740	5,357,728
Restricted stock units issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	7,008,107	8,791,928
Class A common stock reserved for Twilio.org
Anti-dilutive securities
Antidilutive securities (in shares)	663,061	751,469
Class A common stock committed under ESPP
Anti-dilutive securities
Antidilutive securities (in shares)	106,054	103,132
Convertible senior notes
Anti-dilutive securities
Antidilutive securities (in shares)	0	4,331,844
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)	288,755	0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 1,286	$ 294	$ 2,176	$ 1,271

Subsequent Events (Details)

Subsequent Events (Details) - Zipwhip - USD ($) $ in Millions	Jul. 14, 2021	Jun. 30, 2021
Subsequent Events
Acquisition related costs		$ 2.5
Subsequent Events
Subsequent Events
Purchase price, as adjusted	$ 850