Segment Reporting - Summary Information for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	[1]
Segment Reporting Information [Line Items]
Resident fees and services	$ 1,393,473	$ 1,159,449	$ 2,753,747	$ 2,291,134
Rental income	335,811	383,439	753,463	767,498
Interest income	63,453	38,710	116,117	75,115
Other income	32,147	83,880	61,298	92,460
Total revenues	1,824,884	1,665,478	3,684,625	3,226,207
Property operating expenses	1,111,297	958,672	2,208,210	1,916,425
Consolidated net operating income (loss)	713,587	706,806	1,476,415	1,309,782
Depreciation and amortization	382,045	341,945	747,908	681,057
Interest expense	133,424	152,337	280,742	296,740
General and administrative expenses	55,565	44,287	108,883	88,658
Loss (gain) on derivatives and financial instruments, net	(5,825)	1,280	(8,879)	2,210
Loss (gain) on extinguishment of debt, net	1,705	1	1,711	6
Provision for loan losses, net	5,163	2,456	6,177	3,233
Impairment of assets	2,394	1,086	45,725	13,715
Other expenses	48,684	11,069	62,815	33,814
Income (loss) from continuing operations before income taxes and other items	90,432	152,345	231,333	190,349
Income tax (expense) benefit	(1,101)	(3,503)	(7,292)	(6,548)
Income (loss) from unconsolidated entities	4,896	(40,332)	(2,887)	(47,403)
Gain (loss) on real estate dispositions, net	166,443	(2,168)	171,150	(1,421)
Income (loss) from continuing operations	260,670	106,342	392,304	134,977
Net income (loss)	260,670	106,342	392,304	134,977
Total assets	45,533,937		45,533,937		$ 44,012,166
Seniors Housing Operating
Segment Reporting Information [Line Items]
Rental income			265,959	222,452
Operating Segments | Seniors Housing Operating
Segment Reporting Information [Line Items]
Resident fees and services	1,393,473	1,159,449	2,753,747	2,291,134
Rental income	0	0	0	0
Interest income	16,077	2,095	21,100	4,646
Other income	1,900	2,895	3,363	5,340
Total revenues	1,411,450	1,164,439	2,778,210	2,301,120
Property operating expenses	1,034,906	885,187	2,054,253	1,768,971
Consolidated net operating income (loss)	376,544	279,252	723,957	532,149
Depreciation and amortization	253,531	220,428	490,327	440,835
Interest expense	7,326	16,136	18,512	27,623
General and administrative expenses	0	0	0	0
Loss (gain) on derivatives and financial instruments, net	0	0	0	0
Loss (gain) on extinguishment of debt, net	1,705	0	1,711	0
Provision for loan losses, net	6,142	1,867	7,710	1,794
Impairment of assets	1,778	0	45,109	12,629
Other expenses	37,724	8,060	46,481	25,639
Income (loss) from continuing operations before income taxes and other items	68,338	32,761	114,107	23,629
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	(2,526)	(39,445)	(6,793)	(55,034)
Gain (loss) on real estate dispositions, net	137,061	(2,096)	141,663	(1,263)
Income (loss) from continuing operations	202,873	(8,780)	248,977	(32,668)
Net income (loss)	202,873	(8,780)	248,977	(32,668)
Total assets	26,007,665		26,007,665
Operating Segments | Triple-net
Segment Reporting Information [Line Items]
Resident fees and services	0	0	0	0
Rental income	141,151	198,916	362,895	401,335
Interest income	46,528	36,520	93,317	70,283
Other income	931	66,692	2,130	68,575
Total revenues	188,610	302,128	458,342	540,193
Property operating expenses	10,495	10,598	21,312	22,321
Consolidated net operating income (loss)	178,115	291,530	437,030	517,872
Depreciation and amortization	61,766	55,234	124,301	109,762
Interest expense	352	(795)	710	(810)
General and administrative expenses	0	0	0	0
Loss (gain) on derivatives and financial instruments, net	(5,825)	1,280	(8,879)	2,210
Loss (gain) on extinguishment of debt, net	0	0	0	0
Provision for loan losses, net	(962)	591	(1,529)	1,441
Impairment of assets	616	1,086	616	1,086
Other expenses	8,420	818	9,625	3,285
Income (loss) from continuing operations before income taxes and other items	113,748	233,316	312,186	400,898
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	2,614	(630)	(539)	7,802
Gain (loss) on real estate dispositions, net	21,268	(72)	21,294	448
Income (loss) from continuing operations	137,630	232,614	332,941	409,148
Net income (loss)	137,630	232,614	332,941	409,148
Total assets	9,454,889		9,454,889
Operating Segments | Outpatient Medical
Segment Reporting Information [Line Items]
Resident fees and services	0	0	0	0
Rental income	194,660	184,523	390,568	366,163
Interest income	848	95	1,700	186
Other income	2,577	1,574	4,979	4,674
Total revenues	198,085	186,192	397,247	371,023
Property operating expenses	61,185	58,697	123,648	117,062
Consolidated net operating income (loss)	136,900	127,495	273,599	253,961
Depreciation and amortization	66,748	66,283	133,280	130,460
Interest expense	1,310	3,152	3,028	7,256
General and administrative expenses	0	0	0	0
Loss (gain) on derivatives and financial instruments, net	0	0	0	0
Loss (gain) on extinguishment of debt, net	0	1	0	6
Provision for loan losses, net	(17)	(2)	(4)	(2)
Impairment of assets	0	0	0	0
Other expenses	331	647	940	1,194
Income (loss) from continuing operations before income taxes and other items	68,528	57,414	136,355	115,047
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	4,808	(257)	4,445	(171)
Gain (loss) on real estate dispositions, net	8,114	0	8,193	(606)
Income (loss) from continuing operations	81,450	57,157	148,993	114,270
Net income (loss)	81,450	57,157	148,993	114,270
Total assets	7,487,100		7,487,100
Non-segment/Corporate
Segment Reporting Information [Line Items]
Resident fees and services	0	0	0	0
Rental income	0	0	0	0
Interest income	0	0	0	0
Other income	26,739	12,719	50,826	13,871
Total revenues	26,739	12,719	50,826	13,871
Property operating expenses	4,711	4,190	8,997	8,071
Consolidated net operating income (loss)	22,028	8,529	41,829	5,800
Depreciation and amortization	0	0	0	0
Interest expense	124,436	133,844	258,492	262,671
General and administrative expenses	55,565	44,287	108,883	88,658
Loss (gain) on derivatives and financial instruments, net	0	0	0	0
Loss (gain) on extinguishment of debt, net	0	0	0	0
Provision for loan losses, net	0	0	0	0
Impairment of assets	0	0	0	0
Other expenses	2,209	1,544	5,769	3,696
Income (loss) from continuing operations before income taxes and other items	(160,182)	(171,146)	(331,315)	(349,225)
Income tax (expense) benefit	(1,101)	(3,503)	(7,292)	(6,548)
Income (loss) from unconsolidated entities	0	0	0	0
Gain (loss) on real estate dispositions, net	0	0	0	0
Income (loss) from continuing operations	(161,283)	(174,649)	(338,607)	(355,773)
Net income (loss)	(161,283)	$ (174,649)	(338,607)	$ (355,773)
Total assets	$ 2,584,283		$ 2,584,283

[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.