Assets and Liabilities Measured at Fair Value - Fair Value Hierarchy (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Current	$ 541,000,000	$ 72,000,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax		0
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	892,000,000	464,000,000
Marketable Securities, Current	541,000,000	72,000,000
Available-for-sale Securities	313,000,000	16,000,000
Debt Instrument, Fair Value Disclosure	427,000,000
Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	159,000,000	164,000,000
Available-for-sale Securities	307,000,000
Debt Instrument, Fair Value Disclosure	427,000,000
Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	733,000,000	300,000,000
Marketable Securities, Current	541,000,000	72,000,000
Available-for-sale Securities	6,000,000	16,000,000
Corporate Debt Securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities gross unrealized loss	1,000,000	1,000,000
Expedia
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	34,000,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Expedia | Other Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time deposits	2,000,000
Expedia | Other Current Assets | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	37,000,000	48,000,000
Expedia | Other Assets, net | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Noncurrent	$ 6,000,000	$ 16,000,000