Loans Receivable and Investments - 2020 Activity (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 31, 2020 USD ($)	Jul. 31, 2020 property	Jul. 31, 2020 senior_housing	Apr. 30, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance on loans receivable and investments		$ (9,082)	$ 24,238	$ 0
Gains (losses) on real estate loan investments		1,448	167	$ 0
Non-mortgage loans receivable, net		$ 19,024	57,077
Number of real estate properties | property		1,200
Secured/mortgage loans and other, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Securities, Held-to-maturity		$ 488,913	555,840
COVID-19 Impact
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff			34,700
Financing Receivable, Allowance for Credit Loss			10,500
Holiday Management Company [Member] | Secured/mortgage loans and other, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Securities, Held-to-maturity								$ 66,000
Debt securities, effective interest rate								9.20%
Brookdale Senior Living
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-mortgage loans receivable, net					$ 45,000
Brookdale Senior Living | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of real estate properties						5	5
Brookdale Senior Living | Secured/mortgage loans and other, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Securities, Held-to-maturity					$ 78,000
Full Repayments on Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from collection of loans receivable	$ 16,500		$ 106,100
Debt Instrument, Weighted Average Interest		8.30%	8.30%
Gains (losses) on real estate loan investments			$ 1,400