Fair Value Measurements - Estimated Fair Values of Assets Measured on Nonrecurring Basis (Detail) - Fair Value Measurements Nonrecurring [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in affiliates, Fair Value	[1]			$ 7
Property and equipment, Fair Value		$ 92	[2]	6	[1]
Total, Fair Value		92	[2]	13	[1]
Investments in affiliates, Impairment loss				17
Property and equipment, Impairment loss		10		14
Intangibles, Impairment loss				1
Total, Impairment loss		$ 10		$ 32

[1] Fair value for the year ended December 31, 2016, is measured using significant unobservable inputs (Level 3). We estimated fair value of the assets using discounted cash flow analyses, with estimated stabilized growth rates ranging from 1% to 3%, a discounted cash flow term between 10 to 15 years, terminal capitalization rates ranging from 5% to 8% percent, and discount rates ranging from 7% to 10%. The discount and terminal capitalization rates used for the fair value of the assets reflect the risk profile of the market where the property is located and are not necessarily indicative of our hotel portfolio as a whole

[2] Fair value for the year ended December 31, 2017, is based upon the contracted sales price for a property, less costs to sell, as applicable (Level 2).