Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 20, 2020	Jun. 28, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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 Public Float			$ 15.9
Documents Incorporated by Reference	Portions of the registrant's definitive Proxy Statement for the 2020 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December 31, 2019
Entity Central Index Key	0001447669
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Common Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		128,303,845
Common Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		11,406,940