Acquisitions and Dipositions - Dispositions, Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of equity method investments		$ 42
Gain on sale from equity method investee	$ 55	$ 10
Disposal Group, Disposed of by Sale, Not Discontinued Operations | The Tremont Chicago Hotel at Magnificent Mile, Le Centre Sheraton Montreal Hotel, Westin Denarau Island Resort, and The Sheraton Fiji Resort
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of property				$ 79
Disposal Group, Disposed of by Sale, Not Discontinued Operations | The Sheraton Buenos Aires Hotel & Convention Center and Park Tower
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of property			$ 53