Goodwill and Intangible Assets, Net - Changes in Goodwill by Reportable Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 8,120	$ 8,229
Additions	21	31
Impairment of goodwill	0	(86)	$ 0
Foreign exchange translation and other	(14)	(54)
Goodwill, Ending Balance	8,127	8,120	8,229
Core OTA
Goodwill [Line Items]
Goodwill, Beginning Balance	4,741	4,840
Additions	0	0
Impairment of goodwill		(86)
Foreign exchange translation and other	0	(13)
Goodwill, Ending Balance	4,741	4,741	4,840
trivago
Goodwill [Line Items]
Goodwill, Beginning Balance	561	588
Additions	0	0
Impairment of goodwill		0
Foreign exchange translation and other	(12)	(27)
Goodwill, Ending Balance	549	561	588
Vrbo
Goodwill [Line Items]
Goodwill, Beginning Balance	2,682	2,656
Additions	21	31
Impairment of goodwill		0
Foreign exchange translation and other	0	(5)
Goodwill, Ending Balance	2,703	2,682	2,656
Egencia
Goodwill [Line Items]
Goodwill, Beginning Balance	136	145
Additions	0
Impairment of goodwill		0
Foreign exchange translation and other	(2)	(9)
Goodwill, Ending Balance	$ 134	$ 136	$ 145