Segment Reporting - Summary of Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenues [Abstract]
Amount	$ 1,662,013	$ 1,473,844	$ 4,888,220	$ 4,342,084
Assets:
Amount	41,654,702		41,654,702		$ 37,893,233	[1]
Resident fees and services
Revenues [Abstract]
Non-cash consideration	1,199,808	1,068,706	3,490,942	3,073,040
United States
Revenues [Abstract]
Amount	1,384,381	1,220,306	4,072,915	3,578,201
Assets:
Amount	34,990,725		34,990,725		31,740,907
United States | Resident fees and services
Revenues [Abstract]
Non-cash consideration	967,360	855,822	2,806,301	2,438,744
United Kingdom
Revenues [Abstract]
Amount	153,765	136,896	455,669	420,739
Assets:
Amount	3,385,630		3,385,630		3,476,793
United Kingdom | Resident fees and services
Revenues [Abstract]
Non-cash consideration	111,947	99,405	334,544	300,121
Canada
Revenues [Abstract]
Amount	123,867	116,642	359,636	343,144
Assets:
Amount	3,278,347		3,278,347		$ 2,675,533
Canada | Resident fees and services
Revenues [Abstract]
Non-cash consideration	$ 120,501	$ 113,479	$ 350,097	$ 334,175
Revenue | Geographic Concentration Risk
Assets:
Percentage	100.00%	100.00%	100.00%	100.00%
Revenue | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	100.00%	100.00%	100.00%	100.00%
Revenue | United States | Geographic Concentration Risk
Assets:
Percentage	83.20%	82.80%	83.30%	82.40%
Revenue | United States | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	80.70%	80.10%	80.40%	79.30%
Revenue | United Kingdom | Geographic Concentration Risk
Assets:
Percentage	9.30%	9.30%	9.30%	9.70%
Revenue | United Kingdom | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	9.30%	9.30%	9.60%	9.80%
Revenue | Canada | Geographic Concentration Risk
Assets:
Percentage	7.50%	7.90%	7.40%	7.90%
Revenue | Canada | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	10.00%	10.60%	10.00%	10.90%
Assets | Geographic Concentration Risk
Assets:
Percentage			100.00%		100.00%
Assets | United States | Geographic Concentration Risk
Assets:
Percentage			84.00%		83.80%
Assets | United Kingdom | Geographic Concentration Risk
Assets:
Percentage			8.10%		9.20%
Assets | Canada | Geographic Concentration Risk
Assets:
Percentage			7.90%		7.00%

[1] The consolidated balance sheet at December 31, 2022 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements.