Segment Information - Revenue by Business Model and Service Type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 2,609	$ 2,508
Lodging
Segment Reporting Information [Line Items]
Revenue	1,725	1,612
Air
Segment Reporting Information [Line Items]
Revenue	248	242
Advertising and media
Segment Reporting Information [Line Items]
Revenue	264	282
Other
Segment Reporting Information [Line Items]
Revenue	372	372
Sales Channel, Through Intermediary | Merchant
Segment Reporting Information [Line Items]
Revenue	1,392	1,334
Sales Channel, Through Intermediary | Agency
Segment Reporting Information [Line Items]
Revenue	686	658
Sales Channel, Through Intermediary | Advertising and media
Segment Reporting Information [Line Items]
Revenue	264	282
Sales Channel, Through Intermediary | Vrbo
Segment Reporting Information [Line Items]
Revenue	$ 267	$ 234