Goodwill and Intangible Assets, Net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Impairment of goodwill			$ 86	$ 0	$ 0
Impairment of intangible assets			42	0	$ 35
Core OTA
Goodwill [Line Items]
Impairment of goodwill			86
Impairment of intangible assets	$ 42
Accumulated goodwill impairment loss	2,600		2,600	$ 2,500
Nonrecurring Basis | Reporting Unit Within Core Online Travel Companies [Member]
Goodwill [Line Items]
Impairment of goodwill	$ 25	$ 61	$ 86