Segment and Geographic Information - Summary of Segment Information (Parenthetical) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
General and administrative	[1]	$ 173	$ 187	$ 177
Advertising expense		118	423	544
Reportable Segments | Hotels, Media & Platform
Segment Reporting Information [Line Items]
General and administrative		70	69	77
Advertising expense		$ 10	$ 77	$ 122

[1] Includes stock-based compensation expense as follows (Note 15):