Credit Concentration (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($) properties		Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Concentration by investment:
Percent of NOI	[1],[2]	100.00%
Net Operating Income		$ 2,404,177	[1]	$ 2,237,569	$ 1,940,188
Total revenues		$ 4,281,160		$ 3,859,826	$ 3,343,546
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers				46.00%
Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,313
Genesis HealthCare
Concentration by investment:
Percent of NOI	[1],[2]	16.00%
Net Operating Income	[1]	$ 373,577
Genesis HealthCare | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	86
Sunrise Senior Living
Concentration by investment:
Percent of NOI	[1],[2],[3]	13.00%
Net Operating Income	[1],[3]	$ 308,771
Total revenues		$ 998,783
Sunrise Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	152
Revera
Concentration by investment:
Percent of NOI	[1],[2]	6.00%
Net Operating Income	[1]	$ 153,712
Revera | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	98
Brookdale Senior Living
Concentration by investment:
Percent of NOI	[1],[2]	6.00%
Net Operating Income	[1]	$ 151,337
Brookdale Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	148
Benchmark Senior Living
Concentration by investment:
Percent of NOI	[1],[2]	4.00%
Net Operating Income	[1]	$ 96,958
Benchmark Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	48
Remaining Portfolio
Concentration by investment:
Percent of NOI	[1],[2]	55.00%
Net Operating Income	[1]	$ 1,319,822
Remaining Portfolio | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	781

[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 46% of total NOI in 2015.

[3] Revera owns a controlling interest in Sunrise Senior Living. For the year ended December 31, 2016, we recognized $998,783,000 of revenue from Sunrise Senior Living.