Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Property, primarily differences in depreciation and amortization, the tax basis of land assets and the treatment of interests and certain costs	$ (310,756,000)		$ (332,111,000)		$ (287,165,000)
Operating loss and interest deduction carryforwards	366,590,000		343,843,000		103,733,000
Expense accruals and other	13,984,000		11,511,000		3,093,000
Valuation allowance	(326,837,000)		(281,954,000)		(60,994,000)
Net deferred tax liabilities	257,019,000	[1]	258,711,000	[1]	241,333,000	[1]
Deferred tax assets	2,700,000		2,000,000
Increase (decrease) in net deferred tax liability	(1,700,000)		17,400,000
Net difference between tax bases and the reported amount of REIT assets and liabilities	5,100,000,000		5,300,000,000
Period during which subject built-in gains tax (in years)	10 years
NOL carryforward related to TRS entities	289,000,000
NOL carryforward related to REIT	692,000,000
NHP
Business acquisition
Net operating loss, carryforward			38,700,000
Atria Senior Living Acquisition [Member]
Business acquisition
Net operating loss, carryforward			$ 546,800,000

[1] 2012 and 2011 includes approximately $2.7 million and $2.0 million, respectively, of deferred tax assets included in other assets on our Consolidated Balance Sheets.