Segment Information - Revenue by Services and Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 920	$ 1,504	$ 566	$ 2,209	$ 2,747	$ 3,558	$ 3,153	$ 2,609	$ 5,199	$ 12,067	$ 11,223
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									3,511	6,869	6,202
All other countries
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									1,688	5,198	5,021
Lodging
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									4,051	8,362	7,597
Air
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									105	869	881
Advertising and media
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									405	1,104	1,103
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									638	1,732	1,642
Other | Bodybuilding.com
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									59	58
Sales Channel, Through Intermediary | Merchant
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									3,261	6,763	6,125
Sales Channel, Through Intermediary | Agency
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									1,267	3,882	3,701
Sales Channel, Through Intermediary | Advertising, media and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									$ 671	$ 1,422	$ 1,397