Accounting Policies (Impairment & Other) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 segment	Dec. 31, 2012	Dec. 31, 2011
Impairment of Long-Lived and Intangible Assets
Real estate impairment charges	$ 51,500,000	$ 35,600,000	$ 0
Deferred Financing Costs
Deferred financing costs, net of accumulated amortization	62,215,000	42,551,000
Amortized costs included in interest expense	13,500,000	10,500,000	17,800,000
Fair Values of Financial Instruments
Unit conversion factor for common stock	0.7866
Revenue Recognition
Straight-line rent receivables	150,829,000	120,325,000
Allowance for straight-line rent receivable	$ 101,400,000	$ 59,700,000
Term of resident lease agreements, minimum (in months)	12 months
Term of resident lease agreements, maximum (in months)	18 months
Notice period to cancel lease agreements by the resident (in days)	30 days
Segment Reporting
Number of reportable business segments	3
KINDRED
Real estate properties
Number of lease agreements containing revenue parameters for rental increases	4