Contingencies - Guarantees (Details) In Millions, unless otherwise specified								3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Lease Obligations and Debt Securities Payable USD ($)	Mar. 31, 2013 Property Lease Guarantee ExecuStay USD ($)	Mar. 31, 2013 Primary Obligor USD ($)	Mar. 31, 2013 Primary Obligor Debt Service USD ($)	Mar. 31, 2013 Primary Obligor Not Yet In Effect Condition Debt Service USD ($)	Mar. 31, 2013 Secondarily Liable USD ($)	Mar. 31, 2013 Secondarily Liable Sunrise Senior Living Inc USD ($)	Dec. 30, 2011 Secondarily Liable Sunrise Senior Living Inc USD ($)	Mar. 31, 2013 Secondarily Liable MVW Spin-off USD ($)	Mar. 31, 2013 Secondarily Liable MVW Spin-off Expiration in 2022 USD ($) Contract	Mar. 31, 2013 Secondarily Liable MVW Spin-off Expiration in 2022 SGD	Mar. 31, 2013 Secondarily Liable Property Lease Guarantee Sunrise Senior Living Inc USD ($)	Dec. 30, 2011 Secondarily Liable Property Lease Guarantee Sunrise Senior Living Inc USD ($)	Dec. 30, 2011 Secondarily Liable Property Lease Guarantee Sunrise Senior Living Inc Key Bank Letter of Credit USD ($)	Mar. 31, 2013 Secondarily Liable Property Lease Guarantee Renaissance Hotel Group N.V. USD ($)	Mar. 31, 2013 Secondarily Liable Property Lease Guarantee Renaissance Hotel Group N.V. EUR (€)	Sep. 09, 2005 Secondarily Liable Property Lease Guarantee Renaissance Hotel Group N.V. EUR (€)	Mar. 31, 2013 Secondarily Liable Debt Securities Payable USD ($)	Mar. 31, 2013 Secondarily Liable Debt Securities Payable Sunrise Senior Living Inc USD ($)	Mar. 31, 2013 Secondarily Liable Debt Securities Payable CNL Retirement Properties Inc USD ($)	Mar. 31, 2013 Secondarily Liable Debt Securities Payable Five Star Senior Living USD ($)	Mar. 31, 2013 Secondarily Liable Lease is Terminated by End of 2013 Property Lease Guarantee ExecuStay USD ($)	Mar. 31, 2013 Secondarily Liable Lease is Terminated After End of 2013 Property Lease Guarantee ExecuStay USD ($)	Mar. 31, 2013 Other Current Liabilities Primary Obligor USD ($)	Mar. 31, 2013 Other Long Term Liabilities Primary Obligor USD ($)
Commitments and Contingencies Disclosure [Line Items]
Funding guarantees, minimum term	4 years
Funding guarantees, maximum term	10 years
Liability for guarantees				$ 60	$ 7																				$ 5	$ 55
Maximum potential amount of future fundings				209	88	34	114			27	16	20	84						30	5	24	1	11	6
Guarantee obligations, carrying value		3	1							2
Cash collateral in the event funding is required									3
Length of operating lease extension														5 years
Cash collateralized for lease guarantee for period from 2014 until 2018														1
Letter of credit provided by Sunrise, amount available															85
Collateral for continuing lease obligation contingency, future minimum annual payments due from 2014 until 2018													1
Additional cash collateralized during the period for guarantee obligations								2
Annual rent payments, approximately																6
Remaining rent payments, approximately																37
Guarantee obligations, cash collateralized																$ 5	€ 4	€ 35
Number of guarantees provided											1	1