Credit Concentration (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017 USD ($) properties	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) properties	Jun. 30, 2016 USD ($)	Dec. 31, 2016
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,274		1,274
Percent of NOI	[1],[2]			100.00%
Net Operating Income | $		$ 556,747	$ 617,825	$ 1,108,876	$ 1,215,237
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers						45.00%
Genesis HealthCare [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	86		86
Genesis HealthCare [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]			9.00%
Net Operating Income | $	[1]			$ 98,225
Sunrise Senior Living Inc. [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	153		153
Sunrise Senior Living Inc. [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]			14.00%
Net Operating Income | $	[1],[3]			$ 155,331
Brookdale [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	137		137
Brookdale [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]			7.00%
Net Operating Income | $	[1]			$ 75,862
Revera [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[3]	98		98
Revera [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2],[3]			7.00%
Net Operating Income | $	[1],[3]			$ 75,937
Benchmark Senior Living [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	48		48
Benchmark Senior Living [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]			4.00%
Net Operating Income | $	[1]			$ 48,095
Remaining Portfolio [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	752		752
Remaining Portfolio [Member] | Net Operating Income [Member]
Concentration by investment:
Percent of NOI	[1],[2]			59.00%
Net Operating Income | $	[1]			$ 655,426

[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 in both our triple-net and seniors housing operating segments.

[2] NOI with our top five relationships comprised 45% of total NOI for the year ending December 31, 2016.

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