Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			5
Revenue	$ 807,980	$ 1,008,949	$ 2,688,028	$ 3,070,450
Segment operating income	146,675	199,084	607,979	665,278
General and administrative expense (including non-cash stock-based compensation expense)	54,138	56,409	161,251	170,296
Facility lease expense	51,620	67,253	178,480	203,610
Depreciation and amortization	87,821	93,550	271,713	284,462
Asset impairment	8,213	2,094	96,729	6,254
Loss (gain) on facility lease termination and modification, net	0	0	0	2,006
Income (loss) from operations	(55,117)	(20,222)	(100,194)	(1,350)
Total assets	7,007,927		7,007,927		$ 7,194,433
Operating Segments | Independent Living
Segment Reporting Information [Line Items]
Revenue	125,858	136,874	391,998	408,519
Segment operating income	42,438	49,414	134,890	153,749
Asset impairment	0	0	31,317	0
Total assets	1,434,312		1,434,312		1,441,652
Operating Segments | Assisted Living and Memory Care
Segment Reporting Information [Line Items]
Revenue	410,631	452,474	1,300,418	1,361,225
Segment operating income	87,152	116,856	306,861	390,699
Asset impairment	8,213	802	51,301	2,340
Total assets	3,853,458		3,853,458		4,157,610
Operating Segments | CCRCs
Segment Reporting Information [Line Items]
Revenue	79,252	100,104	262,370	305,084
Segment operating income	9,954	14,472	43,735	53,956
Asset impairment	0	1,252	12,173	1,252
Total assets	759,743		759,743		742,809
Operating Segments | Health Care Services
Segment Reporting Information [Line Items]
Revenue	95,795	111,785	297,779	337,751
Segment operating income	1,462	4,778	2,033	22,118
Total assets	238,621		238,621		256,715
Operating Segments | Management Services
Segment Reporting Information [Line Items]
Revenue	96,444	207,712	435,463	657,871
Segment operating income	5,669	13,564	120,460	44,756
Asset impairment	0	$ 40	1,938	$ 2,662
Total assets	721,793		721,793		$ 595,647
CARES Act
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund			20,000,000
CARES Act | Independent Living
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	100		100
CARES Act | Assisted Living and Memory Care
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	1,900		2,100
CARES Act | CCRCs
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	2,800		12,400
CARES Act | Health Care Services
Segment Reporting Information [Line Items]
Cash made available for Provider Relief Fund	$ 5,900		$ 22,900