Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment									5
Revenues	$ 1,068,930	$ 1,120,062	$ 1,155,200	$ 1,187,234	$ 1,165,890	$ 1,177,988	$ 1,186,472	$ 1,216,766	$ 4,531,426	$ 4,747,116	$ 4,976,980
Segment Operating Income									1,067,869	1,253,830	1,439,981
General and administrative (including non-cash stock-based compensation expense)									250,495	255,446	313,409
Transaction costs									8,980	22,573	3,990
Facility lease expense									303,294	339,721	373,635
Depreciation and amortization									447,455	482,077	520,402
Goodwill and asset impairment	37,927	5,500	16,103	430,363	18,966	368,551	1,559	20,706	489,893	409,782	248,515
Loss on facility lease termination and modification, net	13,197	2,337	146,467	0					162,001	14,276	11,113
Income (loss) from operations	(46,455)	$ 3,626	$ (137,589)	$ (413,831)	2,625	$ (350,970)	$ 30,174	$ 48,126	(594,249)	(270,045)	(31,083)
Total interest expense									280,269	326,154	385,617
Total capital expenditures for property, plant and equipment, and leasehold intangibles									220,810	221,476	300,113
Assets	6,467,260				7,675,449				6,467,260	7,675,449
Health Care Services
Segment Reporting Information [Line Items]
Goodwill and asset impairment									9,100	14,600
Operating segments | Independent Living
Segment Reporting Information [Line Items]
Revenues									599,977	654,196	679,503
Segment Operating Income									240,609	271,417	294,530
Facility lease expense									93,496	117,131	120,272
Depreciation and amortization									91,899	95,226	94,049
Goodwill and asset impairment									2,013	2,968	31,384
Total interest expense									58,783	55,436	56,827
Total capital expenditures for property, plant and equipment, and leasehold intangibles									51,510	47,309	59,978
Assets	1,104,774				1,266,076				1,104,774	1,266,076
Operating segments | Assisted Living and Memory Care
Segment Reporting Information [Line Items]
Revenues									1,995,851	2,210,688	2,419,459
Segment Operating Income									628,982	749,058	876,817
Facility lease expense									178,716	185,971	193,670
Depreciation and amortization									261,365	290,344	308,639
Goodwill and asset impairment									436,892	342,788	132,389
Total interest expense									174,459	207,861	249,449
Total capital expenditures for property, plant and equipment, and leasehold intangibles									125,750	119,717	156,732
Assets	3,684,170				4,535,114				3,684,170	4,535,114
Operating segments | CCRCs
Segment Reporting Information [Line Items]
Revenues									416,408	468,994	592,826
Segment Operating Income									92,212	106,162	133,409
Facility lease expense									24,856	29,464	51,727
Depreciation and amortization									53,551	44,294	66,431
Goodwill and asset impairment									6,669	18,083	46,329
Total interest expense									26,746	27,665	39,824
Total capital expenditures for property, plant and equipment, and leasehold intangibles									26,615	24,297	37,800
Assets	707,819				667,234				707,819	667,234
Operating segments | Health Care Services
Segment Reporting Information [Line Items]
Revenues									436,975	446,262	476,833
Segment Operating Income									34,080	51,348	64,463
Facility lease expense									0	0	0
Depreciation and amortization									3,201	3,723	4,075
Goodwill and asset impairment									9,055	14,599	1,596
Total interest expense									0	892	1,461
Total capital expenditures for property, plant and equipment, and leasehold intangibles									902	755	1,576
Assets	254,950				257,257				254,950	257,257
Operating segments | Corporate and Management Services
Segment Reporting Information [Line Items]
Revenues									1,082,215	966,976	808,359
Segment Operating Income									71,986	75,845	70,762
Facility lease expense									6,226	7,155	7,966
Depreciation and amortization									37,439	48,490	47,208
Goodwill and asset impairment									35,264	31,344	36,817
Total interest expense									20,281	34,300	38,056
Total capital expenditures for property, plant and equipment, and leasehold intangibles									16,033	29,398	$ 44,027
Assets	$ 715,547				$ 949,768				$ 715,547	$ 949,768