Income Taxes - Schedule of Statutory Federal Income Tax Rate to Income from Continuing Operations Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense at the federal statutory rate of 21% for 2018 and 35% for 2017 and 2016	$ 102	$ 146	$ 97
Foreign tax rate differential	(42)	(82)	(67)
Federal research and development credit	(23)	(16)	(15)
Excess tax benefits related to stock-based compensation	(10)	(60)	(40)
Unrecognized tax benefits and related interest	23	27	33
Change in valuation allowance	8	4	(14)
Return to provision true-ups	(7)	1	(14)
trivago stock-based compensation	7	5	17
State taxes	11	3	0
Non-deductible goodwill impairment	16	0	0
Tax Act transition tax	0	144	0
U.S. statutory tax rate change	0	(158)	0
Global intangible low-taxed income	13	0	0
Foreign-derived intangible income	(38)	0	0
Other, net	27	31	19
Income tax expense	$ 87	$ 45	$ 16