Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 1,019,457	$ 1,155,200	$ 2,061,501	$ 2,342,434
Private pay
Disaggregation of Revenue [Line Items]
Revenue	640,222	735,760	1,288,901	1,478,521
Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	129,049	131,093	256,457	266,332
Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	32,592	29,116	65,984	57,382
Resident fees
Disaggregation of Revenue [Line Items]
Revenue	801,863	895,969	1,611,342	1,802,235
Independent Living | Private pay
Disaggregation of Revenue [Line Items]
Revenue	135,348	158,405	270,393	315,912
Independent Living | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	603	888	1,252	1,778
Independent Living | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Independent Living | Resident fees
Disaggregation of Revenue [Line Items]
Revenue	135,951	159,293	271,645	317,690
Assisted Living and Memory Care | Private pay
Disaggregation of Revenue [Line Items]
Revenue	433,589	503,806	875,500	1,018,070
Assisted Living and Memory Care | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	16,636	18,221	33,251	36,237
Assisted Living and Memory Care | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Assisted Living and Memory Care | Resident fees
Disaggregation of Revenue [Line Items]
Revenue	450,225	522,027	908,751	1,054,307
CCRCs | Private pay
Disaggregation of Revenue [Line Items]
Revenue	71,092	73,392	142,625	144,113
CCRCs | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	20,196	21,379	41,683	45,085
CCRCs | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	9,965	10,025	20,672	20,667
CCRCs | Resident fees
Disaggregation of Revenue [Line Items]
Revenue	101,253	104,796	204,980	209,865
Health Care Services | Private pay
Disaggregation of Revenue [Line Items]
Revenue	193	157	383	426
Health Care Services | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	91,614	90,605	180,271	183,232
Health Care Services | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	22,627	19,091	45,312	36,715
Health Care Services | Resident fees
Disaggregation of Revenue [Line Items]
Revenue	$ 114,434	$ 109,853	$ 225,966	$ 220,373