Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019		Jan. 31, 2020	Jan. 01, 2020	Jan. 01, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Residency agreement term, minimum	30 days
Residency agreement term, maximum	1 year
Maximum period available for occupancy from cessation of significant construction activity	1 year
Advertising expense	$ 11,000	$ 18,000	$ 13,000
Cumulative effect of new accounting principle	7,058,760	7,289,950	6,658,859					$ 6,512,591
Present value of lease liability	204,547	179,895
Right-of-use asset, net	233,942	192,349
Intangible assets, net	$ 519,760	519,917
Building and Building Improvements
Schedule of Equity Method Investments [Line Items]
Property, plant and equipment, useful life	50 years
Brookedale MTCA | CCRC JV Investment
Schedule of Equity Method Investments [Line Items]
Non refundable entrance fee liabilities	$ 496,000	484,000			$ 436,000
Discontinued Operations
Schedule of Equity Method Investments [Line Items]
Advertising expense	3,000	12,000	13,000
ASU 2016-02
Schedule of Equity Method Investments [Line Items]
Present value of lease liability							$ 153,000
Right-of-use asset, net							166,000
Accrued rent							20,000
Intangible assets, net							33,000
Cumulative Dividends In Excess Of Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle	$ (4,120,774)	$ (3,976,232)	(3,601,199)					(2,927,196)
Cumulative Effect, Period of Adoption, Adjustment
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle			(1,524)	[1]		$ 2,000		590	[2]
Cumulative Effect, Period of Adoption, Adjustment | Cumulative Dividends In Excess Of Earnings
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle			$ (1,524)	[1]				$ 590	[2]
Cumulative Effect, Period of Adoption, Adjustment | Cumulative Dividends In Excess Of Earnings | ASU 2016-02
Schedule of Equity Method Investments [Line Items]
Cumulative effect of new accounting principle							$ 1,000

[1] On January 1, 2020, the Company adopted a series of ASUs related to accounting for credit losses and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.

[2] On January 1, 2019, the Company adopted a series of Accounting Standards Updates (“ASUs”) related to accounting for leases, and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.