Credit Concentration (Details) (USD $)	12 Months Ended			12 Months Ended
	Dec. 31, 2013 properties		Dec. 31, 2012	Dec. 31, 2013 Sunrise Senior Living [Member] properties		Dec. 31, 2013 Genesis Health Care LLC [Member] properties		Dec. 31, 2013 Revera [Member] properties		Dec. 31, 2013 Benchmark Senior Living, LLC [Member] properties		Dec. 31, 2013 Belmont Village [Member] properties		Dec. 31, 2013 Remaining Portfolio [Member] properties		Dec. 31, 2012 Top Five Relationships [Member]
Concentration by investment: (1)
Number of properties in diversified portfolio	1,142	[1]		120	[1]	177	[1]	47	[1]	39	[1]	19	[1]	740	[1]
Net real estate investments	$ 21,680,221,000	[1]	$ 17,423,009,000	$ 4,019,340,000	[1]	$ 2,652,988,000	[1]	$ 1,170,552,000	[1]	$ 940,124,000	[1]	$ 850,500,000	[1]	$ 12,046,717,000	[1]
Percent of Investment	100.00%	[1],[2]		19.00%	[1],[2]	12.00%	[1],[2]	5.00%	[1],[2]	4.00%	[1],[2]	4.00%	[1],[2]	56.00%	[1],[2]	37.00%
Credit Concentration (Textuals) [Abstract]
Percentage total investments with top five customers			37.00%

[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] Investments with our top five relationships comprised 37% of total investments at December 31, 2012.