Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			5
Revenue	$ 1,019,457	$ 1,155,200	$ 2,061,501	$ 2,342,434
Segment Operating Income	227,066	285,964	466,194	578,586
General and administrative expense (including non-cash stock-based compensation expense)	57,576	62,907	113,887	144,342
Facility lease expense	67,689	81,960	136,357	162,360
Depreciation and amortization	94,024	116,116	190,912	230,371
Goodwill and asset impairment	3,769	16,103	4,160	446,466
Loss on facility lease termination and modification, net	1,797	146,467	2,006	146,467
Income (loss) from operations	2,211	(137,589)	18,872	(551,420)
Total assets	7,459,482		7,459,482		$ 6,467,260
Operating Segments | Independent Living
Segment Reporting Information [Line Items]
Revenue	135,951	159,293	271,645	317,690
Segment Operating Income	51,459	65,134	104,335	129,556
Total assets	1,469,683		1,469,683		1,104,774
Operating Segments | Assisted Living and Memory Care
Segment Reporting Information [Line Items]
Revenue	450,225	522,027	908,751	1,054,307
Segment Operating Income	133,144	169,737	273,843	346,275
Total assets	4,293,648		4,293,648		3,684,170
Operating Segments | CCRCs Rental
Segment Reporting Information [Line Items]
Revenue	101,253	104,796	204,980	209,865
Segment Operating Income	17,847	23,819	39,484	48,482
Total assets	792,344		792,344		707,819
Operating Segments | Health Care Services
Segment Reporting Information [Line Items]
Revenue	114,434	109,853	225,966	220,373
Segment Operating Income	9,167	10,203	17,340	18,521
Total assets	270,496		270,496		254,950
Operating Segments | Management Services
Segment Reporting Information [Line Items]
Revenue	217,594	259,231	450,159	540,199
Segment Operating Income	15,449	$ 17,071	31,192	$ 35,752
Total assets	$ 633,311		$ 633,311		$ 715,547