Dispositions, Assets Held for Sale and Discontinued Operations (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Real property dispositions:
Total dispositions			$ 165,020,000	$ 115,633,000
Gain (loss) on sales of properties	185,000	10,526,000	56,565,000	20,559,000
Seller financing on sales of real property				(1,470,000)
Proceeds from sales of real property			221,585,000	134,722,000
Revenues:
Rental income	87,000	9,805,000	9,489,000	30,944,000
Expenses:
Interest expense	16,000	2,050,000	1,771,000	6,182,000
Property operating expenses	212,000	1,495,000	2,427,000	4,456,000
Provision for depreciation		3,430,000	2,635,000	10,420,000
Income (loss) from discontinued operations, net	(141,000)	2,830,000	2,656,000	9,886,000
Seniors housing triple-net [Member]
Real property dispositions:
Total dispositions			129,725,000	108,065,000
Medical facilities [Member]
Real property dispositions:
Total dispositions			$ 35,295,000	$ 7,568,000