Segment Reporting - Summary of Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Revenues [Abstract]
Amount	$ 1,824,884	$ 1,665,478	$ 3,684,625	$ 3,226,207
Resident fees and services	1,393,473	1,159,449	2,753,747	2,291,134
Assets:
Amount	45,533,937		45,533,937		$ 44,012,166	[1]
Resident fees and services
Revenues [Abstract]
Resident fees and services	1,393,473	1,159,449	2,753,747	2,291,134
United States
Revenues [Abstract]
Amount	1,530,174	1,392,512	3,077,070	2,688,534
Assets:
Amount	38,799,436		38,799,436		36,929,186
United States | Resident fees and services
Revenues [Abstract]
Resident fees and services	1,148,809	929,997	2,246,148	1,838,941
United Kingdom
Revenues [Abstract]
Amount	163,264	154,028	324,772	301,904
Assets:
Amount	3,604,871		3,604,871		3,587,230
United Kingdom | Resident fees and services
Revenues [Abstract]
Resident fees and services	117,794	113,585	234,673	222,597
Canada
Revenues [Abstract]
Amount	131,446	118,938	282,783	235,769
Assets:
Amount	3,129,630		3,129,630		$ 3,495,750
Canada | Resident fees and services
Revenues [Abstract]
Resident fees and services	$ 126,870	$ 115,867	$ 272,926	$ 229,596
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	83.90%	83.70%	83.50%	83.30%
Revenue | United States | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	82.40%	80.20%	81.60%	80.30%
Revenue | United Kingdom | Geographic Concentration Risk
Assets:
Percentage	8.90%	9.20%	8.80%	9.40%
Revenue | United Kingdom | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	8.50%	9.80%	8.50%	9.70%
Revenue | Canada | Geographic Concentration Risk
Assets:
Percentage	7.20%	7.10%	7.70%	7.30%
Revenue | Canada | Resident fees and services | Geographic Concentration Risk
Assets:
Percentage	9.10%	10.00%	9.90%	10.00%
Assets | Geographic Concentration Risk
Assets:
Percentage			100.00%		100.00%
Assets | United States | Geographic Concentration Risk
Assets:
Percentage			85.20%		83.90%
Assets | United Kingdom | Geographic Concentration Risk
Assets:
Percentage			7.90%		8.20%
Assets | Canada | Geographic Concentration Risk
Assets:
Percentage			6.90%		7.90%

[1] The consolidated balance sheet at December 31, 2023 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.