Credit Concentration (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) property	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Concentration Risk [Line Items]
Total NOI									$ 2,008,144	$ 2,431,264	$ 2,267,482
Percentage total investments with top five customers					37.00%					37.00%
Revenues	$ 1,122,016	$ 1,036,874	$ 1,188,475	$ 1,258,602	$ 1,262,822	$ 1,266,133	$ 1,320,106	$ 1,272,245	4,605,967	$ 5,121,306	$ 4,700,499
Sunrise senior living
Concentration Risk [Line Items]
Revenues									$ 1,147,146
Net Operating Income
Concentration Risk [Line Items]
Number of properties | property	1,493								1,493
Total NOI									$ 2,008,144
Percent of NOI									100.00%
Net Operating Income | Sunrise senior living
Concentration Risk [Line Items]
Number of properties | property	165								165
Total NOI									$ 257,558
Percent of NOI									13.00%
Net Operating Income | ProMedica
Concentration Risk [Line Items]
Number of properties | property	215								215
Total NOI									$ 212,593
Percent of NOI									11.00%
Net Operating Income | Revera
Concentration Risk [Line Items]
Number of properties | property	94								94
Total NOI									$ 100,344
Percent of NOI									5.00%
Net Operating Income | Avery Healthcare
Concentration Risk [Line Items]
Number of properties | property	60								60
Total NOI									$ 75,863
Percent of NOI									4.00%
Net Operating Income | Sagora Senior Living
Concentration Risk [Line Items]
Number of properties | property	31								31
Total NOI									$ 67,399
Percent of NOI									3.00%
Net Operating Income | Remaining portfolio
Concentration Risk [Line Items]
Number of properties | property	928								928
Total NOI									$ 1,294,387
Percent of NOI									64.00%