Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 865,909	$ 1,019,457	$ 1,880,048	$ 2,061,501
Private pay
Disaggregation of Revenue [Line Items]
Revenue	604,192	640,222	1,244,968	1,288,901
Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	102,790	129,049	213,322	256,457
Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	24,647	32,592	56,046	65,984
Total resident fee revenue
Disaggregation of Revenue [Line Items]
Revenue	731,629	801,863	1,514,336	1,611,342
Independent Living | Private pay
Disaggregation of Revenue [Line Items]
Revenue	129,678	135,348	264,968	270,393
Independent Living | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	600	603	1,172	1,252
Independent Living | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Independent Living | Total resident fee revenue
Disaggregation of Revenue [Line Items]
Revenue	130,278	135,951	266,140	271,645
Assisted Living and Memory Care | Private pay
Disaggregation of Revenue [Line Items]
Revenue	414,276	433,589	854,889	875,500
Assisted Living and Memory Care | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	17,880	16,636	34,746	33,251
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 | Total resident fee revenue
Disaggregation of Revenue [Line Items]
Revenue	432,156	450,225	889,635	908,751
CCRCs | Private pay
Disaggregation of Revenue [Line Items]
Revenue	59,980	71,092	124,683	142,625
CCRCs | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	13,744	20,196	33,149	41,683
CCRCs | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	5,301	9,965	15,740	20,672
CCRCs | Total resident fee revenue
Disaggregation of Revenue [Line Items]
Revenue	79,025	101,253	173,572	204,980
Health Care Services | Private pay
Disaggregation of Revenue [Line Items]
Revenue	258	193	428	383
Health Care Services | Government reimbursement
Disaggregation of Revenue [Line Items]
Revenue	70,566	91,614	144,255	180,271
Health Care Services | Other third-party payor programs
Disaggregation of Revenue [Line Items]
Revenue	19,346	22,627	40,306	45,312
Health Care Services | Total resident fee revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 90,170	$ 114,434	$ 184,989	$ 225,966