Credit Concentration (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2015 USD ($) properties		Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Concentration by investment:
Number of properties in diversified portfolio | properties		1,482
Percent of NOI	[1],[2]	100.00%
Net Operating Income		$ 2,237,569	[1]	$ 1,940,188	$ 1,673,795
Total revenues		$ 3,859,826		$ 3,343,546	$ 2,880,608
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers				49.00%
Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,426
Genesis HealthCare [Member]
Concentration by investment:
Percent of NOI	[1],[2]	17.00%
Net Operating Income	[1]	$ 371,170
Genesis HealthCare [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	187
Sunrise [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]	13.00%
Net Operating Income	[1],[3]	$ 299,697
Total revenues		$ 948,347
Sunrise [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	148
Brookdale Member [Member]
Concentration by investment:
Percent of NOI	[1],[2]	7.00%
Net Operating Income	[1]	$ 166,792
Brookdale Member [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	148
Revera Member [Member]
Concentration by investment:
Percent of NOI	[1],[2]	5.00%
Net Operating Income	[1]	$ 109,778
Revera Member [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	97
Benchmark Senior Living Member [Member]
Concentration by investment:
Percent of NOI	[1],[2]	4.00%
Net Operating Income	[1]	$ 98,887
Benchmark Senior Living Member [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	50
Remaining Portfolio Member [Member]
Concentration by investment:
Percent of NOI	[1],[2]	54.00%
Net Operating Income	[1]	$ 1,191,245
Remaining Portfolio Member [Member] | Controlling [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	796

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

[2] Investments with our top five relationships comprised 49% of NOI in 2014.

[3] For the year ended December 31, 2015, we recognized $948,347,000 of revenue from Sunrise Senior Living.