Concentration of Credit Risk - Triple-Net Leased Properties (Details) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2020 USD ($) senior_housing	Dec. 31, 2021 USD ($) property $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 31, 2020 USD ($)	Jul. 31, 2020 property	Jul. 31, 2020	Jul. 31, 2020 shares	Jul. 31, 2020 $ / shares	Jul. 31, 2020 senior_housing
Real estate properties
Other noncash expense		$ (26,404)	$ 779	$ (13,264)
Cash and cash equivalents		149,725	413,327
Non-mortgage loans receivable, net		$ 19,024	57,077
Operating Lease, Lease Income, Lease Payments, Annual Increase							3.00%
Number of real estate properties | property		1,200
Secured/mortgage loans and other, net
Real estate properties
Debt Securities, Held-to-maturity		$ 488,913	555,840
Brookdale Senior Living
Real estate properties
Other noncash expense		$ (42,600)	$ (21,300)
Cash and cash equivalents					$ 162,000
Non-mortgage loans receivable, net					45,000
Stock warrants					28,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares		16.3						16.3
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares		$ 3.00							$ 3.00
Lessor, Operating Lease, Payments to be Received, Next Rolling Twelve Months					100,000
Brookdale Senior Living | Secured/mortgage loans and other, net
Real estate properties
Debt Securities, Held-to-maturity					78,000
Brookdale Senior Living | Collateral Pledged
Real estate properties
Number of real estate properties						5				5
Brookdale Senior Living | Transfer Of Lease Deposit To Cash
Real estate properties
Cash and cash equivalents					47,000
Brookdale Senior Living | Up-front Payment Arrangement
Real estate properties
Contract with Customer, Liability					$ 235,000
Brookdale Senior Living | Customer Concentration Risk | Revenues
Real estate properties
Concentration risk		3.90%	4.40%	4.70%
Brookdale Senior Living | Customer Concentration Risk | Net Operating Income
Real estate properties
Concentration risk		8.60%	9.00%	8.70%
Ardent | Customer Concentration Risk | Revenues
Real estate properties
Concentration risk		3.30%	3.20%	3.10%
Ardent | Customer Concentration Risk | Net Operating Income
Real estate properties
Concentration risk		7.40%	6.60%	5.80%
Kindred | Customer Concentration Risk | Revenues
Real estate properties
Concentration risk		3.80%	3.50%	3.30%
Kindred | Customer Concentration Risk | Net Operating Income
Real estate properties
Concentration risk		7.80%	7.10%	6.30%
Holiday Management Company Member
Real estate properties
Number of real estate properties | senior_housing	26
Gain (Loss) on Contract Termination	$ 50,200
Operating Lease, Lease Termination Consideration Received	99,800
Loans and Leases Receivable, Allowance	49,600
Holiday Management Company Member | Secured/mortgage loans and other, net
Real estate properties
Debt Securities, Held-to-maturity	66,000
Holiday Management Company Member | Transfer Of Lease Deposit To Cash
Real estate properties
Cash and cash equivalents	$ 33,800
Experienced Operators | Senior Living Communities, Operations to be Transitioned
Real estate properties
Number of real estate properties | property		90