Loans Receivable - Narrative (Details)	1 Months Ended									3 Months Ended				6 Months Ended			12 Months Ended	18 Months Ended
	Jul. 31, 2022 USD ($)	May 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jul. 31, 2021 USD ($)	Jun. 30, 2021 USD ($) loan	May 31, 2021 USD ($) loan	Apr. 30, 2021 USD ($) loan property	Jan. 31, 2021 USD ($) facility	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($) loan	Mar. 31, 2021 USD ($)	Jun. 30, 2022 USD ($) loan	Dec. 31, 2021 USD ($) loan	Jun. 30, 2021 USD ($) loan	Dec. 31, 2021 USD ($) loan	Jun. 30, 2022 USD ($)	Dec. 31, 2020 USD ($)
Loans Receivable:
Net cash provided by financing activities														$ (72,082,000)		$ (2,009,272,000)
Gain (loss) on sales of real estate, net										$ 10,340,000		$ 175,238,000		14,196,000		175,238,000
Financing receivable, after allowance for credit loss										413,962,000				413,962,000	$ 415,811,000		$ 415,811,000	$ 413,962,000
Reserves for loans receivable										2,015,000				$ 2,015,000	$ 1,813,000		$ 1,813,000	2,015,000	$ 10,280,000
Gain (loss) on sale of financing receivable											$ 23,000,000
Number of loans sold | loan														1	2		6
Proceeds from sale of receivables															$ 53,000,000
Credit loss reserve on unfunded loan commitments										400,000				$ 400,000	300,000		$ 300,000	400,000
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
Sunrise Senior Housing Portfolio | SHOP | Subsequent Event
Loans Receivable:
Capital expenditure funding, amount committed	$ 40,000,000
Secured mortgage loans
Loans Receivable:
Financing receivable, gross										387,447,000				387,447,000	396,281,000		396,281,000	387,447,000
Mezzanine and Other
Loans Receivable:
Reserves for loans receivable										6,000				6,000	9,000		9,000	6,000	$ 7,128,000
SHOP
Loans Receivable:
Number of assets to be sold | facility									16
SHOP | Sunrise Senior Housing Portfolio
Loans Receivable:
Number of assets to be sold | facility									32
Proceeds from sale of property									$ 664,000,000
Proceeds from the collection of loans receivable			$ 8,000,000			246,000,000
Gain (loss) on sales of real estate, net						7,000,000
Financing receivable, after allowance for credit loss										157,000,000				157,000,000	165,000,000		165,000,000	157,000,000
SHOP | Sunrise Senior Housing Portfolio | Subsequent Event
Loans Receivable:
Proceeds from the collection of loans receivable	27,000,000
Capital expenditure funding, decrease in amount	$ 7,000,000
SHOP | Discovery SHOP Portfolio
Loans Receivable:
Gain (loss) on sales of real estate, net								$ 0
SHOP | Mezzanine and Other | Discovery SHOP Portfolio
Loans Receivable:
Number of loans held for sale | loan								2
Gain (loss) on sale of financing receivable								$ 0
Number of loans sold | property								2
Secured mortgage loans
Loans Receivable:
Financing receivable, after allowance for credit loss						$ 53,000,000						$ 53,000,000				$ 53,000,000
Principal repayments received		$ 2,000,000		$ 15,000,000	$ 8,000,000		$ 10,000,000
Number of loans held for sale | loan						2						2				2
Financing receivable, gross						$ 64,000,000						$ 64,000,000				$ 64,000,000
Decrease in financing receivable												11,000,000
Reserves for loans receivable						$ 8,000,000						8,000,000				8,000,000
Gain (loss) on sale of financing receivable												(3,000,000)				(3,000,000)
Number of loans receivable | loan							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		9,000,000		2,000,000		10,000,000
Noncash interest income, acceleration recognition												$ 7,000,000				$ 7,000,000
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 | Brookedale MTCA | Other Non-Reporting Segment | Lessor Asset Under Operating Lease
Loans Receivable:
Financing receivable, after allowance for credit loss										$ 30,000,000				$ 30,000,000	$ 24,000,000		$ 24,000,000	$ 30,000,000