Contingencies - Guarantees (Details) In Millions, unless otherwise specified	12 Months Ended																											12 Months Ended		0 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2014 EUR (€)	Dec. 31, 2014 Lease Obligations and Debt Securities Payable USD ($)	Dec. 31, 2014 Primary Obligor USD ($)	Dec. 31, 2014 Primary Obligor Other Current Liabilities USD ($)	Dec. 31, 2014 Primary Obligor Other Long Term Liabilities USD ($)	Dec. 31, 2014 Primary Obligor Guarantee, Indebtedness of Others USD ($)	Dec. 31, 2014 Primary Obligor Guarantee, Operating Profit USD ($)	Dec. 31, 2014 Primary Obligor Guarantee Type, Other USD ($)	Dec. 31, 2014 Primary Obligor Not Yet In Effect Condition Guarantee, Indebtedness of Others USD ($)	Dec. 31, 2014 Primary Obligor Not Yet In Effect Condition Guarantee, Operating Profit USD ($)	Dec. 31, 2014 Primary Obligor Not Yet In Effect Condition Other Guarantees USD ($)	Dec. 31, 2014 Secondarily Liable USD ($)	Dec. 31, 2014 Secondarily Liable Debt Securities Payable USD ($)	Dec. 31, 2014 Sunrise Senior Living Inc Secondarily Liable Property Lease Guarantee USD ($)	Dec. 31, 2014 Sunrise Senior Living Inc Secondarily Liable Debt Securities Payable USD ($)	Dec. 31, 2014 CNL Retirement Properties Inc Secondarily Liable Debt Securities Payable USD ($)	Dec. 31, 2014 Renaissance Hotel Group N.V. Secondarily Liable Property Lease Guarantee USD ($)	Dec. 31, 2014 Renaissance Hotel Group N.V. Secondarily Liable Property Lease Guarantee EUR (€)	Sep. 09, 2005 Renaissance Hotel Group N.V. Secondarily Liable Property Lease Guarantee EUR (€)	Dec. 31, 2014 MVW Spin-off Secondarily Liable USD ($) guarantee	Dec. 31, 2014 Letter of Credit Key Bank Sunrise Senior Living Inc Secondarily Liable Property Lease Guarantee USD ($)	Dec. 31, 2014 Expiration in 2019 MVW Spin-off Secondarily Liable USD ($)	Dec. 31, 2014 Expiration in 2022 MVW Spin-off Secondarily Liable USD ($)	Dec. 31, 2014 Expiration in 2022 MVW Spin-off Secondarily Liable SGD	Dec. 31, 2014 ExecuStay Property Lease Guarantee USD ($)	Dec. 31, 2014 ExecuStay Secondarily Liable Lease is Terminated After End of 2013 Property Lease Guarantee USD ($)	Dec. 31, 2014 Lower Limit	Dec. 31, 2014 Upper Limit	Jan. 14, 2014 New York City EDITION Hotel	Jan. 14, 2014 New York City EDITION Hotel USD ($)	Dec. 31, 2014 Group 4 Investment in Other Joint Venture Commitment USD ($)	Dec. 31, 2014 Group 4 Investment in Other Joint Venture Commitment EUR (€)
Commitments and Contingencies Disclosure [Line Items]
Guarantee obligations, term																												4 years	10 years
Liability for guarantees			$ 3	$ 55	$ 4	$ 51	$ 14	$ 40	$ 1												$ 1					$ 1
Maximum potential amount of future fundings				149			49	86	14	16	26	1	83	22	61	3	19				12		4	8	11		6
Guarantor obligations, number of guarantees																					2
Loan commitment, put option agreement, obligation to acquire property, term																														2 years
Loan commitment, put option agreement, obligation to acquire property, amount																															315
Loan commitment, put option agreement, obligation to acquire property, extended term																														3 years
Cash collateral in the event funding is required															1
Letter of credit provided by Sunrise, amount available																						85
Line of credit facility provided by third party, current borrowing capacity for period																						71
Collateral for continuing lease obligation contingency, future minimum annual payments due															1
Annual rent payments, approximately																		6
Remaining rent payments, approximately																		26
Guarantee obligations, cash collateralized																		3	2	35
Contingent acquisition period																																6 years	6 years
Amount of deposit used for contingent joint venture interest acquisition	18	15
Deposits in conjunction with contingent obligation to acquire the interest in joint ventures																																$ 13	€ 11