Credit Concentration (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 properties		Dec. 31, 2012
Concentration by investment:
Number of Properties	1,027	[1]
Total Investment	$ 18,879,252	[1]
Percent of Investment	100.00%	[2]
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers			37.00%
Genesis HealthCare [Member]
Concentration by investment:
Number of Properties	175	[1],[3]
Total Investment	2,662,118	[1],[3]
Percent of Investment	14.00%	[2],[3]
Benchmark Senior Living [Member]
Concentration by investment:
Number of Properties	36	[1]
Total Investment	836,346	[1]
Percent of Investment	4.00%	[2]
Merrill Gardens [Member]
Concentration by investment:
Number of Properties	48	[1]
Total Investment	1,075,791	[1]
Percent of Investment	6.00%	[2]
Remaining Portfolio [Member]
Concentration by investment:
Number of Properties	678	[1]
Total Investment	10,757,586	[1]
Percent of Investment	57.00%	[2]
Belmont Village [Member]
Concentration by investment:
Number of Properties	19	[1]
Total Investment	883,126	[1]
Percent of Investment	5.00%	[2]
Sunrise Senior Living [Member]
Concentration by investment:
Number of Properties	71	[1]
Total Investment	$ 2,664,285	[1]
Percent of Investment	14.00%	[2]

[1] Excludes our share of investments in unconsolidated entities. Please see Note 7 for additional information.

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

[3] Genesis is in our seniors housing triple-net segment whereas the other top five relationships are in our seniors housing operating segment.