Investments in Unconsolidated Entities (Summary of Investments in Unconsolidated Entities) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Equity investments	$ 744,151,000		$ 479,629,000
Senior Housing Facilities Triple Net [Member]
Schedule of Equity Method Investments [Line Items]
Equity investments	31,511,000	[1]	27,513,000	[1]
Senior Housing Facilities Triple Net [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	10.00%	[1]
Senior Housing Facilities Triple Net [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.00%	[1]
Seniors Housing Operating [Member]
Schedule of Equity Method Investments [Line Items]
Equity investments	539,147,000		263,838,000
Seniors Housing Operating [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	10.00%
Seniors Housing Operating [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Medical Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Equity investments	$ 173,493,000		$ 188,278,000
Medical Facilities [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	36.00%
Medical Facilities [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.00%

[1] (1) As of December 31, 2013, asset amounts include an available-for-sale equity investment. See Note 16 for additional information.