Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Valuation Allowance [Line Items]
Effective income tax rate	30.00%	28.30%	27.60%	30.50%
Provision for income taxes	$ (178)	$ (97)	$ (298)	$ (204)
Favorable settlement of uncertain tax position	12		12
Tax positions taken in the current period			20
Unfavorable comparison to prior year valuation allowance			15
Increase from gain on sale of hotel			9
Cash paid for income taxes, net of refunds			201	$ 128
Accounting Standards Update 2016-09
Valuation Allowance [Line Items]
Provision for income taxes	$ 13		$ 56

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of decrease in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of increase in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

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