Supplemental Disclosure of Cash Flow Information - Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Supplemental Cash Flow Information [Abstract]
Interest paid	$ 188,791	$ 204,696	$ 244,469
Income taxes paid, net of refunds	5,923	8,878	1,534
Capital expenditures, net of related payables	176,657	185,871	304,092
Loss (gain) on debt modification and extinguishment, net	(1,932)	10,896	(5,247)
Accounts receivable, net	(502)	(24,277)	(292)
Investments in unconsolidated ventures	5,436	4,082	4,346
Prepaid expenses and other assets, net	(15,483)	24,707	55,873
Refundable fees and deferred revenue	(10,066)	62,614	(25,117)
Loss (gain) on sale of assets, net	(288,835)	(374,532)	(7,245)
Capital expenditures, net of related payables:
Supplemental Cash Flow Information [Abstract]
Capital expenditures, net of related payables	176,657	185,871	304,092
Trade accounts payable	(6,061)	4,766	8,891
Acquisition of communities from Healthpeak:
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	0	286,734	0
Operating lease right-of-use assets	0	(63,285)	0
Financing lease obligations	0	129,196	0
Operating lease obligations	0	74,335	0
Loss (gain) on debt modification and extinguishment, net	0	(19,731)	0
Net cash paid	0	407,249	0
Master Agreement with Ventas:
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	0	(66,444)	0
Operating lease right-of-use assets	0	(153,213)	0
Financing lease obligations	0	7,077	0
Operating lease obligations	0	362,944	0
Net cash paid	0	119,180	0
Other assets, net	0	(42,354)	0
Long-term debt	0	34,053	0
Additional paid-in-capital	0	(22,883)	0
Proceeds from HCS Sale, net:
Supplemental Cash Flow Information [Abstract]
Trade accounts payable	1,387	0	0
Property, plant and equipment and leasehold intangibles, net	(1,806)	0	0
Operating lease right-of-use assets	(8,145)	0	0
Operating lease obligations	8,145	0	0
Accounts receivable, net	(57,582)	0	0
Investments in unconsolidated ventures	100,000	0	0
Goodwill	(126,810)	0	0
Prepaid expenses and other assets, net	(32,963)	0	0
Accrued expenses	25,226	0	0
Refundable fees and deferred revenue	57,314	0	0
Other liabilities	9,165	0	0
Loss (gain) on sale of assets, net	(286,489)	0	0
Net cash received	(312,558)	0	0
Acquisition of other assets, net of related payables and cash received:
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	0	684	44
Financing lease obligations	0	64,260	0
Net cash paid	0	64,944	497
Other intangible assets, net	0	0	453
Proceeds from sale of CCRC Venture, net:
Supplemental Cash Flow Information [Abstract]
Investments in unconsolidated ventures	0	14,848	0
Other liabilities	0	60,748	0
Loss (gain) on sale of assets, net	0	(369,831)	0
Current portion of long-term debt	0	34,706	0
Net cash received	0	(289,225)	0
Proceeds from sale of other assets, net:
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	(878)	(938)	(379)
Prepaid expenses and other assets, net	(1,983)	(1,318)	(4,422)
Other liabilities	75	786	1,479
Loss (gain) on sale of assets, net	(2,346)	(4,701)	(7,245)
Assets held for sale	(16,166)	(34,348)	(79,054)
Investments in unconsolidated ventures	0	0	(156)
Net cash received	(21,448)	(42,091)	(92,735)
Non-Development | Capital expenditures, net of related payables:
Supplemental Cash Flow Information [Abstract]
Capital expenditures, net of related payables	137,410	139,592	235,797
Development | Capital expenditures, net of related payables:
Supplemental Cash Flow Information [Abstract]
Capital expenditures, net of related payables	3,208	13,667	24,595
Non-development - Reimbursable | Capital expenditures, net of related payables:
Supplemental Cash Flow Information [Abstract]
Capital expenditures, net of related payables	$ 42,100	$ 27,846	$ 34,809