Credit Concentration - Summary of Credit Concentration (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) property	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) property	Jun. 30, 2020 USD ($)	Dec. 31, 2020
Concentration Risk [Line Items]
Total NOI	$ 498,335	$ 527,711	$ 933,071	$ 1,104,532
Percentage total investments with top five customers					36.00%
Net operating income | Credit Concentration Risk
Concentration Risk [Line Items]
Number of Properties | property	1,516		1,516
Total NOI			$ 933,071
Percent of NOI			100.00%
Net operating income | Credit Concentration Risk | ProMedica
Concentration Risk [Line Items]
Number of Properties | property	217		217
Total NOI			$ 111,157
Percent of NOI			12.00%
Net operating income | Credit Concentration Risk | Sunrise Senior Living
Concentration Risk [Line Items]
Number of Properties | property	166		166
Total NOI			$ 109,494
Percent of NOI			12.00%
Net operating income | Credit Concentration Risk | Revera
Concentration Risk [Line Items]
Number of Properties | property	85		85
Total NOI			$ 45,928
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			$ 41,536
Percent of NOI			5.00%
Net operating income | Credit Concentration Risk | Genesis Healthcare
Concentration Risk [Line Items]
Number of Properties | property	15		15
Total NOI			$ 36,677
Percent of NOI			4.00%
Net operating income | Credit Concentration Risk | Remaining portfolio
Concentration Risk [Line Items]
Number of Properties | property	972		972
Total NOI			$ 588,279
Percent of NOI			62.00%