Credit Concentration (Details) $ in Thousands		3 Months Ended										12 Months Ended
		Dec. 31, 2017 USD ($) properties		Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	[4]	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) properties		Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Concentration by investment:
Percent of NOI	[1],[2]											100.00%
Net Operating Income												$ 2,232,716	[1]	$ 2,404,177	$ 2,237,569
Total revenues		$ 1,104,257	[3]	$ 1,091,483	$ 1,058,602	$ 1,062,298	$ 1,078,321	$ 1,079,133		$ 1,076,657	$ 1,047,050	$ 4,316,641		$ 4,281,160	$ 3,859,826
Credit Concentration (Textual) [Abstract]
Percentage total investments with top five customers														45.00%
Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	1,286										1,286
Sunrise Senior Living
Concentration by investment:
Percent of NOI	[1],[2],[5]											14.00%
Net Operating Income	[1],[5]											$ 315,409
Total revenues												$ 1,032,562
Sunrise Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[5]	158										158
Genesis HealthCare
Concentration by investment:
Percent of NOI	[1],[2]											9.00%
Net Operating Income	[1]											$ 190,506
Genesis HealthCare | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	86										86
Revera
Concentration by investment:
Percent of NOI	[1],[2],[5]											7.00%
Net Operating Income	[1],[5]											$ 156,698
Revera | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1],[5]	98										98
Brookdale Senior Living
Concentration by investment:
Percent of NOI	[1],[2]											7.00%
Net Operating Income	[1]											$ 151,026
Brookdale Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	137										137
Benchmark Senior Living
Concentration by investment:
Percent of NOI	[1],[2]											4.00%
Net Operating Income	[1]											$ 97,779
Benchmark Senior Living | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	48										48
Remaining Portfolio
Concentration by investment:
Percent of NOI	[1],[2]											59.00%
Net Operating Income	[1]											$ 1,321,298
Remaining Portfolio | Net Operating Income [Member]
Concentration by investment:
Number of properties in diversified portfolio | properties	[1]	759										759

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

[3] The decrease in net income (loss) and amounts per share are primarily attributable to $99,821,100 impairment of assets and $62,966,000 provision for loan losses recognized in the fourth quarter as compared to none in the third quarter.

[4] The increase in net income and amounts per share are primarily attributable to gains on sales of real estate of $162,351,000 for the third quarter as compared to gains of $1,530,000 for the second quarter.

[5] Revera owns a controlling interest in Sunrise Senior Living. For the year ended December 31, 2017, we recognized $1,032,562,000 of revenue from properties managed by Sunrise Senior Living.