Credit Concentration (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) property	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) property	Jun. 30, 2019 USD ($)	Dec. 31, 2019
Concentration Risk [Line Items]
Total NOI	$ 527,711	$ 618,979	$ 1,104,532	$ 1,220,417
Percentage total investments with top five customers					37.00%
Net operating income
Concentration Risk [Line Items]
Number of Properties | property	1,526		1,526
Total NOI			$ 1,104,532
Percent of NOI			100.00%
Net operating income | Sunrise Senior Living
Concentration Risk [Line Items]
Number of Properties | property	165		165
Total NOI			$ 134,872
Percent of NOI			12.00%
Net operating income | ProMedica
Concentration Risk [Line Items]
Number of Properties | property	215		215
Total NOI			$ 106,530
Percent of NOI			10.00%
Net operating income | Genesis Healthcare
Concentration Risk [Line Items]
Number of Properties | property	52		52
Total NOI			$ 58,831
Percent of NOI			5.00%
Net operating income | Revera
Concentration Risk [Line Items]
Number of Properties | property	94		94
Total NOI			$ 57,268
Percent of NOI			5.00%
Net operating income | Avery Healthcare
Concentration Risk [Line Items]
Number of Properties | property	59		59
Total NOI			$ 37,298
Percent of NOI			3.00%
Net operating income | Remaining portfolio
Concentration Risk [Line Items]
Number of Properties | property	941		941
Total NOI			$ 709,733
Percent of NOI			65.00%