Credit Concentration (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) property	Mar. 31, 2019 USD ($)	Dec. 31, 2019
Concentration Risk [Line Items]
Total NOI	$ 576,821	$ 601,438
Percentage total investments with top five customers			37.00%
Net Operating Income
Concentration Risk [Line Items]
Number of Properties | property	1,563
Total NOI	$ 576,821
Percent of NOI	100.00%
Net Operating Income | Sunrise Senior Living
Concentration Risk [Line Items]
Number of Properties | property	165
Total NOI	$ 81,577
Percent of NOI	14.00%
Net Operating Income | ProMedica
Concentration Risk [Line Items]
Number of Properties | property	215
Total NOI	$ 53,498
Percent of NOI	9.00%
Net Operating Income | Revera
Concentration Risk [Line Items]
Number of Properties | property	94
Total NOI	$ 32,874
Percent of NOI	6.00%
Net Operating Income | Genesis Healthcare
Concentration Risk [Line Items]
Number of Properties | property	52
Total NOI	$ 29,391
Percent of NOI	5.00%
Net Operating Income | Belmont Village
Concentration Risk [Line Items]
Number of Properties | property	21
Total NOI	$ 19,615
Percent of NOI	3.00%
Net Operating Income | Remaining portfolio
Concentration Risk [Line Items]
Number of Properties | property	1,016
Total NOI	$ 359,866
Percent of NOI	63.00%