Segment Information - Revenue by Business Model and Service Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,504	$ 3,558	$ 4,279	$ 9,320
Lodging
Segment Reporting Information [Line Items]
Revenue	1,229	2,575	3,258	6,468
Air
Segment Reporting Information [Line Items]
Revenue	27	202	67	678
Advertising and media
Segment Reporting Information [Line Items]
Revenue	94	312	322	861
Other
Segment Reporting Information [Line Items]
Revenue	154	469	632	1,313
Other | Bodybuilding.com
Segment Reporting Information [Line Items]
Revenue		24	59	24
Sales Channel, Through Intermediary | Merchant
Segment Reporting Information [Line Items]
Revenue	1,032	1,980	2,740	5,173
Sales Channel, Through Intermediary | Agency
Segment Reporting Information [Line Items]
Revenue	329	1,177	996	3,066
Sales Channel, Through Intermediary | Advertising, media and other
Segment Reporting Information [Line Items]
Revenue	$ 143	$ 401	$ 543	$ 1,081