Credit Concentration (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 properties	Dec. 31, 2013
Concentration by investment:
Number of properties in diversified portfolio	1,145
Net real estate investments	$ 21,617,299,000	$ 21,680,221,000
Percent of Investment	100.00%
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers		44.00%
Genesis HealthCare [Member]
Concentration by investment:
Number of properties in diversified portfolio	178
Net real estate investments	2,673,389,000
Percent of Investment	12.00%
Benchmark Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio	39
Net real estate investments	933,823,000
Percent of Investment	4.00%
Remaining Portfolio [Member]
Concentration by investment:
Number of properties in diversified portfolio	741
Net real estate investments	12,039,229,000
Percent of Investment	56.00%
Belmont Village [Member]
Concentration by investment:
Number of properties in diversified portfolio	19
Net real estate investments	841,800,000
Percent of Investment	4.00%
Sunrise Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio	121
Net real estate investments	4,013,200,000
Percent of Investment	19.00%
Revera [Member]
Concentration by investment:
Number of properties in diversified portfolio	47
Net real estate investments	$ 1,115,858,000
Percent of Investment	5.00%