Investments in Unconsolidated Entities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Investments In Unconsolidated Joint Ventures [Line Items]
Total revenues	$ 2,880,608,000		$ 1,805,044,000		$ 1,313,182,000
Net income	138,280,000		294,840,000		212,716,000
Net real estate investments	21,680,221,000	[1]	17,423,009,000
Total other assets	1,403,736,000		2,126,100,000
Total assets	23,083,957,000		19,549,109,000
Total liabilities	11,292,587,000		8,993,998,000
Redeemable noncontrolling interests	35,039,000		34,592,000
Total equity	11,756,331,000		10,520,519,000		7,278,647,000	4,733,100,000
Non Controlling [Member]
Investments In Unconsolidated Joint Ventures [Line Items]
Total revenues	1,619,251,000	[2]	324,941,000	[3]	160,860,000
Net income	(17,439,000)	[2]	10,702,000	[3]	20,124,000
Net real estate investments	1,589,590,000		1,675,877,000
Total other assets	564,109,000		110,629,000
Total assets	2,153,699,000		1,786,506,000
Total liabilities	1,227,053,000		970,521,000
Redeemable noncontrolling interests	29,482,000		21,694,000
Total equity	$ 897,164,000		$ 794,291,000

[1] Genesis is in our seniors housing triple-net segment. Sunrise, Revera, and Belmont Village are in our seniors housing operating segment. Benchmark is in both our seniors housing triple-net and seniors housing operating segments

[2] Beginning January 9, 2013, includes the financial information for the Sunrise management company and the five remaining unconsolidated Sunrise properties discussed above.

[3] Beginning May 1, 2012, includes the financial information for the Chartwell unconsolidated entities discussed above.