Credit Concentration - Summary of Credit Concentration (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($)	Dec. 31, 2020
Concentration Risk [Line Items]
Total NOI	$ 510,397	$ 402,157	$ 1,443,468	$ 1,506,689
Percentage total investments with top five customers					36.00%
Net operating income | Credit Concentration Risk
Concentration Risk [Line Items]
Number of Properties | property	1,606		1,606
Total NOI			$ 1,443,468
Percent of NOI			100.00%
Net operating income | Credit Concentration Risk | ProMedica
Concentration Risk [Line Items]
Number of Properties | property	205		205
Total NOI			$ 168,832
Percent of NOI			12.00%
Net operating income | Credit Concentration Risk | Sunrise Senior Living
Concentration Risk [Line Items]
Number of Properties | property	155		155
Total NOI			$ 157,256
Percent of NOI			11.00%
Net operating income | Credit Concentration Risk | Revera
Concentration Risk [Line Items]
Number of Properties | property	85		85
Total NOI			$ 71,139
Percent of NOI			5.00%
Net operating income | Credit Concentration Risk | Avery Healthcare
Concentration Risk [Line Items]
Number of Properties | property	61		61
Total NOI			$ 62,325
Percent of NOI			5.00%
Net operating income | Credit Concentration Risk | Belmont Village
Concentration Risk [Line Items]
Number of Properties | property	21		21
Total NOI			$ 45,475
Percent of NOI			4.00%
Net operating income | Credit Concentration Risk | Remaining portfolio
Concentration Risk [Line Items]
Number of Properties | property	1,079		1,079
Total NOI			$ 938,441
Percent of NOI			63.00%