Loans Receivable - Narrative (Details)	1 Months Ended							3 Months Ended			12 Months Ended			15 Months Ended
	Feb. 28, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jul. 31, 2021 USD ($)	Jun. 30, 2021 USD ($) property	May 31, 2021 USD ($) property	Apr. 30, 2021 USD ($) property	Jan. 31, 2021 USD ($) property	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($) property	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) property	Dec. 31, 2021 USD ($) loan	Mar. 31, 2022 USD ($)	Dec. 31, 2020 USD ($)
Loans Receivable:
Net cash provided by financing activities								$ (18,511,000)		$ (924,119,000)
Gain (loss) on sales of real estate, net								3,856,000		0
Financing receivable, after allowance for credit loss								409,753,000			$ 415,811,000	$ 415,811,000	$ 415,811,000	$ 409,753,000
Reserves for loans receivable								1,944,000			1,813,000	$ 1,813,000	$ 1,813,000	1,944,000	$ 10,280,000
Number of loans sold												6	2
Proceeds from sale of receivables											53,000,000
Gain (loss) on sale of financing receivable								23,000,000
Credit loss reserve on unfunded loan commitments								300,000			300,000	$ 300,000	$ 300,000	300,000
Sunrise Senior Housing Portfolio | SHOP
Loans Receivable:
Net cash provided by financing activities							$ 410,000,000
Capital expenditure funding, amount committed	$ 47,000,000			$ 56,000,000			$ 92,000,000
Capital expenditure funding, cost of capital, percent committed							65.00%
Capital expenditure funding, amount funded														400,000
Secured mortgage loans
Loans Receivable:
Financing receivable, gross								388,746,000			396,281,000	396,281,000	396,281,000	388,746,000
Secured Loans
Loans Receivable:
Reserves for loans receivable								1,938,000			1,804,000	$ 1,804,000	1,804,000	1,938,000	$ 3,152,000
SHOP
Loans Receivable:
Number of assets to be sold | property							16					15
SHOP | Sunrise Senior Housing Portfolio
Loans Receivable:
Number of assets to be sold | property							32
Proceeds from sale of property							$ 664,000,000
Proceeds from the collection of loans receivable	$ 8,000,000			$ 246,000,000
Financing receivable, after allowance for credit loss								157,000,000			165,000,000	$ 165,000,000	165,000,000	157,000,000
SHOP | Discovery SHOP Portfolio
Loans Receivable:
Number of assets to be sold | property						10
Gain (loss) on sales of real estate, net						$ 0
SHOP | Secured Loans | Discovery SHOP Portfolio
Loans Receivable:
Number of loans held for sale | property						2
Number of loans sold | property						2
Gain (loss) on sale of financing receivable						$ 0
Secured mortgage loans
Loans Receivable:
Number of loans held for sale | property				2					2
Financing receivable, gross				$ 64,000,000					$ 64,000,000
Decrease in financing receivable									11,000,000
Financing receivable, after allowance for credit loss				53,000,000					53,000,000
Reserves for loans receivable				$ 8,000,000					$ 8,000,000
Principal repayments received		$ 15,000,000	$ 8,000,000		$ 10,000,000
Number of loans receivable | property					1
SHOP
Loans Receivable:
Proceeds from sale of property							230,000,000
Net cash provided by financing activities							150,000,000
Gain (loss) on sales of real estate, net							$ 59,000,000			$ 16,000,000
Loans receivable, market rate										5.25%
Non-cash interest income								1,000,000		$ 2,000,000
SHOP | Minimum
Loans Receivable:
Loans receivable, stated interest rate										3.50%
Interest income, amortization period (in years)										1 year
SHOP | Maximum
Loans Receivable:
Loans receivable, stated interest rate										4.50%
Interest income, amortization period (in years)										3 years
SHOP | Discovery SHOP Portfolio
Loans Receivable:
Proceeds from sale of property						334,000,000
Gain (loss) on sales of real estate, net						$ 9,000,000
CCRC JV | Lessor Asset Under Operating Lease | Brookedale MTCA | Other Non-Reporting Segment
Loans Receivable:
Financing receivable, after allowance for credit loss								$ 25,000,000			$ 24,000,000	$ 24,000,000	$ 24,000,000	$ 25,000,000