Investments in Unconsolidated Entities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				3 Months Ended						3 Months Ended			3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Senior housing - triple net [Member] properties		Mar. 31, 2012 Senior housing - triple net [Member]		Dec. 31, 2012 Senior housing - triple net [Member]		Mar. 31, 2013 Senior housing - operating [Member] properties	Mar. 31, 2012 Senior housing - operating [Member]	Dec. 31, 2012 Senior housing - operating [Member]	Mar. 31, 2013 Medical facilities [Member] properties	Mar. 31, 2012 Medical facilities [Member]	Dec. 31, 2012 Medical facilities [Member]	Dec. 31, 2010 Strategic Medical Office Partnership [Member] properties	Dec. 31, 2010 Strategic Medical Office Partnership [Member] Controlling [Member] properties	Dec. 31, 2010 Strategic Medical Office Partnership [Member] Non Controlling [Member] properties	Mar. 31, 2013 Chartwell [Member]	Dec. 31, 2012 Chartwell [Member] properties	Dec. 31, 2012 Chartwell [Member] Controlling [Member] properties	Dec. 31, 2012 Chartwell [Member] Non Controlling [Member] properties	Mar. 31, 2013 Forest City [Member]	Dec. 31, 2010 Forest City [Member] properties	Mar. 31, 2013 Sunrise [Member]	Mar. 31, 2013 Sunrise [Member] Non Controlling [Member] properties	Mar. 31, 2013 Management Buyer [Member]
Schedule of Equity Method Investments [Line Items]
Income from unconsolidated entities	$ 2,262		$ 1,532		$ 1,290	[1]	$ 1	[1]			$ (1,548)	$ (330)		$ 2,520	$ 1,861
Equity Investments	781,792			438,936	32,895	[1]			34,618	[1]	561,409		217,701	187,488		186,617				223,134				174,692		359,575
Investment Percentage Range	10% to 49%	[1]									33% to 50%			36% to 49%
Number of properties in portfolio					0	[1]					93			13			17	11	6		42	3	39		7		54
Percentage of partnership owned																					50.00%				49.00%			20.00%
Unamortized investment																				$ 7,858

[1] (1) Asset amounts include an available-for-sale equity investment. See Note 16 for additional information.