Segment Reporting - Summary of Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenues:
Amount	$ 7,991,118	$ 6,637,995	$ 5,860,615
Resident fees and services	6,027,149	4,753,804	4,173,711
Assets:
Amount	51,044,308	44,012,166
Seniors Housing Operating
Revenues:
Resident fees and services	587,224	466,162	410,749
Operating Segments | Seniors Housing Operating
Revenues:
Amount	6,035,461	4,763,547	4,237,550
Resident fees and services	6,027,149	4,753,804	4,173,711
Assets:
Amount	30,094,016	24,622,107
Operating Segments | Triple-net
Revenues:
Amount	788,771	887,106	790,711
Resident fees and services	0	0	0
Assets:
Amount	7,934,415	8,394,073
Operating Segments | Outpatient Medical
Revenues:
Amount	802,113	750,489	678,455
Resident fees and services	0	0	0
Assets:
Amount	7,530,815	7,327,102
Non-segment/Corporate
Revenues:
Amount	364,773	236,853	153,899
Resident fees and services	0	0	0
Assets:
Amount	5,485,062	3,668,884
United States
Revenues:
Amount	6,564,077	5,521,933	4,843,417
Resident fees and services	4,808,221	3,811,915	3,325,466
Assets:
Amount	41,966,871	36,929,186
United Kingdom
Revenues:
Amount	872,479	606,750	558,308
Resident fees and services	683,803	447,219	401,195
Assets:
Amount	5,892,598	3,587,230
Canada
Revenues:
Amount	554,562	509,312	458,890
Resident fees and services	535,125	494,670	$ 447,050
Assets:
Amount	$ 3,184,839	$ 3,495,750
Revenue | Geographic Concentration Risk
Assets:
Percentage	100.00%	100.00%	100.00%
Revenue | United States | Geographic Concentration Risk
Assets:
Percentage	82.10%	83.20%	82.60%
Revenue | United Kingdom | Geographic Concentration Risk
Assets:
Percentage	10.90%	9.10%	9.50%
Revenue | Canada | Geographic Concentration Risk
Assets:
Percentage	7.00%	7.70%	7.90%
Revenue from Contract with Customer | Geographic Concentration Risk
Assets:
Percentage	100.00%	100.00%	100.00%
Revenue from Contract with Customer | United States | Geographic Concentration Risk
Assets:
Percentage	79.80%	80.20%	79.70%
Revenue from Contract with Customer | United Kingdom | Geographic Concentration Risk
Assets:
Percentage	11.30%	9.40%	9.60%
Revenue from Contract with Customer | Canada | Geographic Concentration Risk
Assets:
Percentage	8.90%	10.40%	10.70%
Assets | Segment Concentration Risk
Assets:
Percentage	100.00%	100.00%
Assets | Segment Concentration Risk | Operating Segments | Seniors Housing Operating
Assets:
Percentage	59.00%	55.90%
Assets | Segment Concentration Risk | Operating Segments | Triple-net
Assets:
Percentage	15.50%	19.10%
Assets | Segment Concentration Risk | Operating Segments | Outpatient Medical
Assets:
Percentage	14.80%	16.60%
Assets | Segment Concentration Risk | Non-segment/Corporate
Assets:
Percentage	10.70%	8.40%
Assets | Geographic Concentration Risk
Assets:
Percentage	100.00%	100.00%
Assets | United States | Geographic Concentration Risk
Assets:
Percentage	82.20%	83.90%
Assets | United Kingdom | Geographic Concentration Risk
Assets:
Percentage	11.50%	8.20%
Assets | Canada | Geographic Concentration Risk
Assets:
Percentage	6.30%	7.90%