Credit Concentration (Details)		3 Months Ended			6 Months Ended
		Jun. 30, 2015 USD ($) properties		Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) properties	Jun. 30, 2014 USD ($)	Dec. 31, 2014
Concentration by investment:
Number of properties in diversified portfolio	[1]	1,350			1,350
Percent of NOI	[1],[2]	100.00%
Net Operating Income | $		$ 558,815,000	[1]	$ 482,692,000	$ 1,076,531,000	$ 943,069,000
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers							49.00%
Genesis HealthCare [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1]	180			180
Percent of NOI	[1],[2]	17.00%
Net Operating Income | $	[1]	$ 179,790,000
Sunrise Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1],[3]	144			144
Percent of NOI	[1],[2],[3]	14.00%
Net Operating Income | $	[1],[3]	$ 148,317,000
Brookdale [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1]	146			146
Percent of NOI	[1],[2]	8.00%
Net Operating Income | $	[1]	$ 83,547,000
Benchmark Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1]	50			50
Percent of NOI	[1],[2]	4.00%
Net Operating Income | $	[1]	$ 47,406,000
Revera [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1],[3]	71			71
Percent of NOI	[1],[2],[3]	4.00%
Net Operating Income | $	[1],[3]	$ 47,995,000
Remaining Portfolio [Member]
Concentration by investment:
Number of properties in diversified portfolio	[1]	759			759
Percent of NOI	[1],[2]	53.00%
Net Operating Income | $	[1]	$ 569,476,000

[1] (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] (2)     NOI with our top five relationships comprised 49% of total NOI for the year ending December 31, 2014

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