Dispositions, Assets Held for Sale and Discontinued Operations (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 properties	Sep. 30, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge	$ 6,952	$ 0	$ 6,952	$ 202
Dispositions Assets Held For Sale And Discontinued Operations (Additional Textual) [Abstract]
Numbers of properties sold			42
Gain (loss) on sales of properties, net	12,827	185	46,046	56,565
Deposited in Section 1031 escrow			152,495
Used from Section 1031 escrow			$ 84,243
Seniors Housing Facilities Triple Net [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real property facilities satisfying held for sale criteria			31
Medical facilities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real property facilities satisfying held for sale criteria			0