Segment Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment		5
Revenue		$ 3,540,195	$ 4,057,088	$ 4,531,426
Segment operating income		797,147	876,544	1,067,869
General and administrative (including non-cash stock-based compensation expense)		206,575	219,289	259,475
Facility operating lease expense		224,033	269,666	303,294
Depreciation and amortization		359,226	379,433	447,455
Asset impairment		107,308	49,266	489,893
Loss (gain) on facility lease termination and modification, net		(2,303)	3,388	162,001
Income (loss) from operations		(97,692)	(44,498)	(594,249)
Total interest expense		208,779	248,341	280,269
Total capital expenditures for property, plant and equipment, and leasehold intangibles		181,105	295,201	220,810
Assets	$ 6,901,758	6,901,758	7,194,433
Independent Living | CARES Act
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	11,800
Assisted Living and Memory Care | CARES Act
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	62,600
CCRCs | CARES Act
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	18,500
Health Care Services | CARES Act
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	22,900
Operating segments | Independent Living
Segment Reporting Information [Line Items]
Revenue		524,421	544,558	599,977
Segment operating income		182,813	203,741	240,609
Facility operating lease expense		60,445	81,680	93,496
Depreciation and amortization		70,803	81,745	91,899
Asset impairment		31,317	1,812	2,013
Total interest expense		44,682	46,713	58,783
Total capital expenditures for property, plant and equipment, and leasehold intangibles		47,889	78,831	51,510
Assets	1,419,838	1,419,838	1,441,652
Operating segments | Assisted Living and Memory Care
Segment Reporting Information [Line Items]
Revenue		1,753,861	1,815,938	1,995,851
Segment operating income		428,601	518,636	628,982
Facility operating lease expense		137,900	157,823	178,716
Depreciation and amortization		224,790	222,574	261,365
Asset impairment		61,640	32,229	436,892
Total interest expense		134,015	166,097	174,459
Total capital expenditures for property, plant and equipment, and leasehold intangibles		90,354	157,845	125,750
Assets	3,787,611	3,787,611	4,157,610
Operating segments | CCRCs
Segment Reporting Information [Line Items]
Revenue		340,337	402,175	416,408
Segment operating income		53,180	72,072	92,212
Facility operating lease expense		20,406	24,248	24,856
Depreciation and amortization		38,426	44,163	53,551
Asset impairment		12,413	4,983	6,669
Total interest expense		19,928	27,426	26,746
Total capital expenditures for property, plant and equipment, and leasehold intangibles		18,709	33,535	26,615
Assets	738,121	738,121	742,809
Operating segments | Health Care Services
Segment Reporting Information [Line Items]
Revenue		389,697	447,260	436,975
Segment operating income		1,863	24,987	34,080
Depreciation and amortization		749	2,247	3,201
Asset impairment		0	7,578	9,055
Total capital expenditures for property, plant and equipment, and leasehold intangibles		515	484	902
Assets	233,178	233,178	256,715
Operating segments | Corporate and Management Services
Segment Reporting Information [Line Items]
Revenue		531,879	847,157	1,082,215
Segment operating income		130,690	57,108	71,986
Facility operating lease expense		5,282	5,915	6,226
Depreciation and amortization		24,458	28,704	37,439
Asset impairment		1,938	2,664	35,264
Total interest expense		10,154	8,105	20,281
Total capital expenditures for property, plant and equipment, and leasehold intangibles		23,638	24,506	$ 16,033
Assets	$ 723,010	$ 723,010	$ 595,647