Contingencies - Commitments and Letters of Credit (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) entity	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 EUR (€) entity
Commitments and Contingencies Disclosure [Line Items]
Amount of deposit used for contingent joint venture interest acquisition	$ 20	€ 15
Loan Commitment, Amount Used for Renovation Shortfalls	5
Letters of credit outstanding	82
Surety bonds issued	159
Equity Investment For Noncontrolling Interest In Partnership Commitment | Full Service and Limited Service | Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Investment commitments	7
Equity Investment For Noncontrolling Interest In Partnership Commitment | Limited Service
Commitments and Contingencies Disclosure [Line Items]
Investment commitments expected to be funded in 2016	3
Investment commitments, funding not expected	19
Equity Investment For Noncontrolling Interest In Partnership Commitment | Limited Service | Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Investment commitments	22
Real Estate Investment | Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Investment commitments	$ 11
Investment in Other Joint Venture Commitment | Group 4
Commitments and Contingencies Disclosure [Line Items]
Acquisition interests in joint ventures | entity	2		2
Contingent acquisition period	6 years	6 years
Deposits in conjunction with contingent obligation to acquire the interest in joint ventures	$ 13		€ 11
Information Technology Hardware, Software, Accounting, Finance, and Maintenance Services
Commitments and Contingencies Disclosure [Line Items]
Purchase obligation	173
Purchase obligation, expected to fund commitments in 2016	71
Purchase obligation, expected to fund commitments in 2017	52
Purchase obligation, expected to fund commitments in 2018	47
Purchase obligation, thereafter	3
Commitments
Commitments and Contingencies Disclosure [Line Items]
Investment commitments, funding not expected	29
North American Full-Service Property
Commitments and Contingencies Disclosure [Line Items]
Construction commitment	75
Construction commitment funded in 2015	3
Construction commitment expected to be funded in 2016	25
Construction commitment expected to be funded in 2017	$ 47