Customer Concentration (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Concentration by investment:
Number of Properties	855
Total Investment	$ 12,417,996
Percent of Investment	100.00%
Customer Concentration (Textuals) [Abstract]
Percentage total investments with top five customers		32.00%
Genesis HealthCare Corporation [Member]
Concentration by investment:
Number of Properties	148
Total Investment	2,479,070
Percent of Investment	20.00%
Benchmark Senior Living, LLC [Member]
Concentration by investment:
Number of Properties	34
Total Investment	908,290
Percent of Investment	7.00%
Merrill Gardens, LLC [Member]
Concentration by investment:
Number of Properties	38
Total Investment	709,874
Percent of Investment	6.00%
Brandywine Senior Living, LLC [Member]
Concentration by investment:
Number of Properties	19
Total Investment	605,383
Percent of Investment	5.00%
Senior Living Communities, LLC [Member]
Concentration by investment:
Number of Properties	12
Total Investment	606,056
Percent of Investment	5.00%
Remaining Portfolio [Member]
Concentration by investment:
Number of Properties	604
Total Investment	$ 7,109,323
Percent of Investment	57.00%