Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on minority equity investments, net			$ (13,000,000)	$ (100,000,000)
Net gains (losses) from foreign currency forward contracts	$ 15,000,000	$ 3,000,000	3,000,000	51,000,000
Impairment of goodwill	0	$ 0	0	61,000,000
Carrying value of cost method investments	467,000,000		467,000,000		$ 476,000,000
Reporting Unit Within Core Online Travel Companies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill				61,000,000
Foreign currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount of foreign currency derivatives	3,900,000,000		3,900,000,000
Recurring Basis | Foreign currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net forward asset	$ 20,000,000		20,000,000		$ 22,000,000
Despegar.com
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on minority equity investments, net			$ (10,000,000)	$ (102,000,000)