Credit Concentration (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2016 USD ($) properties		Mar. 31, 2015 USD ($)	Dec. 31, 2015
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,434
Percent of NOI	[1],[2]	100.00%
Net Operating Income		$ 597,414	[1]	$ 517,716
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers					46.00%
Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]	100.00%
Net Operating Income	[1]	$ 597,414
Genesis HealthCare [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	187
Genesis HealthCare [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]	17.00%
Net Operating Income	[1]	$ 99,894
Sunrise Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	150
Sunrise Senior Living [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]	13.00%
Net Operating Income	[1],[3]	$ 75,953
Brookdale [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	148
Brookdale [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]	7.00%
Net Operating Income	[1]	$ 42,585
Benchmark Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	49
Benchmark Senior Living [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]	4.00%
Net Operating Income	[1]	$ 25,875
Revera [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	97
Revera [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]	6.00%
Net Operating Income	[1],[3]	$ 35,654
Remaining Portfolio [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	803
Remaining Portfolio [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]	53.00%
Net Operating Income	[1]	$ 317,453

[1] (1) Genesis Healthcare is in our triple-net segment. Sunrise Senior Living and Revera are in our seniors housing operating segment. Benchmark Senior Living and Brookdale Senior Living are both in our triple-net and seniors housing operating segments.

[2] (2) NOI with our top five relationships comprised 46% of total NOI for the year ending December 31, 2015.

[3] (3) Revera owns a controlling interest in Sunrise Senior Living.