Net Loss per Share Attributable to Common Stockholders - General Information (Details) - Vote	Dec. 31, 2019	Dec. 31, 2018
Common Class A
Net Loss Per Share Attributable to Common Stockholders
Votes per share	1	1
Common Class B
Net Loss Per Share Attributable to Common Stockholders
Votes per share	10	10

Number of votes per common share a shareholder is entitled.

No definition available.

Name:	twlo_CommonStockVotesPerShare
Namespace Prefix:	twlo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant