Credit Concentration (Details) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2016 USD ($) properties		Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) properties		Jun. 30, 2015 USD ($)	Dec. 31, 2015
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,420			1,420
Percent of NOI	[1],[2]				100.00%
Net Operating Income | $		$ 617,825	[1]	$ 558,815	$ 1,215,237	[1]	$ 1,076,531
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%
Genesis HealthCare [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	187			187
Genesis HealthCare [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]				16.00%
Net Operating Income | $	[1]				$ 195,171
Sunrise Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	143			143
Sunrise Senior Living [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]				13.00%
Net Operating Income | $	[1],[3]				$ 160,057
Brookdale [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	148			148
Brookdale [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]				7.00%
Net Operating Income | $	[1]				$ 84,526
Benchmark Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	49			49
Benchmark Senior Living [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]				4.00%
Net Operating Income | $	[1]				$ 48,880
Revera [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	97			97
Revera [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]				6.00%
Net Operating Income | $	[1],[3]				$ 73,992
Remaining Portfolio [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	796			796
Remaining Portfolio [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]				54.00%
Net Operating Income | $	[1]				$ 652,611

[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.