Credit Concentration (Details) £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2021 GBP (£) property
Concentration Risk [Line Items]
Total NOI	$ 1,967,553	$ 2,008,144	$ 2,431,264
Percentage total investments with top five customers		36.00%
Revenues	4,742,115	$ 4,605,967	$ 5,121,306
Real estate loans receivable, net of credit allowance	1,068,681	$ 443,372
Sunrise
Concentration Risk [Line Items]
Revenues	1,051,094
Safanad
Concentration Risk [Line Items]
Real estate loans receivable, net of credit allowance	$ 750,330			£ 540,000
Net Operating Income | Credit Concentration Risk
Concentration Risk [Line Items]
Number of properties | property	1,651			1,651
Total NOI	$ 1,967,553
Percent of NOI	100.00%
Net Operating Income | Credit Concentration Risk | ProMedica
Concentration Risk [Line Items]
Number of properties | property	205			205
Total NOI	$ 228,052
Percent of NOI	12.00%
Net Operating Income | Credit Concentration Risk | Sunrise
Concentration Risk [Line Items]
Number of properties | property	110			110
Total NOI	$ 195,148
Percent of NOI	10.00%
Net Operating Income | Credit Concentration Risk | Revera
Concentration Risk [Line Items]
Number of properties | property	85			85
Total NOI	$ 90,015
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	$ 84,552
Percent of NOI	4.00%
Net Operating Income | Credit Concentration Risk | HC-One Group
Concentration Risk [Line Items]
Number of properties | property	1			1
Total NOI	$ 65,942
Percent of NOI	3.00%
Net Operating Income | Credit Concentration Risk | Remaining portfolio
Concentration Risk [Line Items]
Number of properties | property	1,189			1,189
Total NOI	$ 1,303,844
Percent of NOI	66.00%