Investments in Unconsolidated Entities (Summary of Investments in Unconsolidated Entities) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	$ 715,468,000		$ 744,151,000
Triple Net [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	31,276,000		31,511,000
Triple Net [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	10.00%	[1]	10.00%	[1]
Triple Net [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.00%	[1]	49.00%	[1]
Seniors Housing Facilities Operating [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	509,743,000		539,147,000
Seniors Housing Facilities Operating [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	10.00%	[1]	10.00%	[1]
Seniors Housing Facilities Operating [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%	[1]	50.00%	[1]
Outpatient Medical [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	$ 174,449,000		$ 173,493,000
Outpatient Medical [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	36.00%	[1]	36.00%	[1]
Outpatient Medical [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.00%	[1]	49.00%	[1]

[1] (1) Excludes ownership of in-substance real estate.