Dispositions, Assets Held for Sale and Discontinued Operations (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013		Dec. 31, 2013
Real property dispositions:
Total dispositions	$ 400,050,000	$ 340,495,000
Net loss (gain) on sales of properties	(42,683,000)	(57,202,000)
Noncash disposition activity		(12,204,000)	[1]
Real property held for sale, net of accumulated depreciation	47,463,000			18,502,000
Proceeds from sales of real property	442,733,000	385,493,000
Seniors Housing Facilities Triple Net [Member]
Real property dispositions:
Total dispositions	56,713,000	138,650,000
Net loss (gain) on sales of properties	6,411,000
Real property held for sale, net of accumulated depreciation	18,502,000
Medical facilities [Member]
Real property dispositions:
Total dispositions	$ 343,337,000	$ 201,845,000

[1] (1) Represents non-cash consideration surrendered in an asset swap transaction. Please see Note 3 for additional information.