Segment Reporting - Summary Information for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	[1]
Segment Reporting Information [Line Items]
Resident fees and services	$ 1,511,524	$ 1,199,808	$ 4,265,271	$ 3,490,942
Rental income	430,486	384,507	1,183,949	1,152,005
Interest income	69,046	42,220	185,163	117,335
Other income	44,607	35,478	105,905	127,938
Total revenues	2,055,663	1,662,013	5,740,288	4,888,220
Property operating expenses	1,212,701	995,273	3,420,911	2,911,698
Consolidated net operating income (loss)	842,962	666,740		1,976,522
Depreciation and amortization	403,779	339,314	1,151,687	1,020,371
Interest expense	139,050	156,532	419,792	453,272
General and administrative expenses	77,901	46,106	186,784	134,764
Loss (gain) on derivatives and financial instruments, net	(9,906)	2,885	(18,785)	5,095
Loss (gain) on extinguishment of debt, net	419	1	2,130	7
Provision for loan losses, net	4,193	4,059	10,370	7,292
Impairment of assets	23,421	7,388	69,146	21,103
Other expenses	20,239	38,220	83,054	72,034
Income (loss) from continuing operations before income taxes and other items	183,866	72,235	415,199	262,584
Income tax (expense) benefit	4,706	(4,584)	(2,586)	(11,132)
Income (loss) from unconsolidated entities	(4,038)	(4,031)	(6,925)	(51,434)
Gain (loss) on real estate dispositions and acquisitions of controlling interests, net	272,266	71,102	443,416	69,681
Income (loss) from continuing operations	456,800	134,722	849,104	269,699
Net income (loss)	456,800	134,722	849,104	269,699
Total assets	48,953,698		48,953,698		$ 44,012,166
Seniors Housing Operating
Segment Reporting Information [Line Items]
Rental income			417,490	341,172
Operating Segments | Seniors Housing Operating
Segment Reporting Information [Line Items]
Resident fees and services	1,511,524	1,199,808	4,265,271	3,490,942
Rental income	0	0	0	0
Interest income	16,328	2,194	37,428	6,840
Other income	2,498	1,897	5,861	7,237
Total revenues	1,530,350	1,203,899	4,308,560	3,505,019
Property operating expenses	1,135,887	918,990	3,190,140	2,687,961
Consolidated net operating income (loss)	394,463	284,909	1,118,420	817,058
Depreciation and amortization	279,693	215,195	770,020	656,030
Interest expense	8,742	14,358	27,254	41,981
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	0	1,711	0
Provision for loan losses, net	5,543	384	13,253	2,178
Impairment of assets	20,887	2,400	65,996	15,029
Other expenses	17,914	34,865	64,395	60,504
Income (loss) from continuing operations before income taxes and other items	61,684	17,707	175,791	41,336
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	4,247	(6,021)	(2,546)	(61,055)
Gain (loss) on real estate dispositions and acquisitions of controlling interests, net	63	71,173	141,726	69,910
Income (loss) from continuing operations	65,994	82,859	314,971	50,191
Net income (loss)	65,994	82,859	314,971	50,191
Total assets	28,900,249		28,900,249
Operating Segments | Triple-net
Segment Reporting Information [Line Items]
Resident fees and services	0	0	0	0
Rental income	227,531	194,912	590,426	596,247
Interest income	51,866	39,928	145,183	110,211
Other income	1,118	1,482	3,248	70,057
Total revenues	280,515	236,322	738,857	776,515
Property operating expenses	9,345	10,044	30,657	32,365
Consolidated net operating income (loss)	271,170	226,278	708,200	744,150
Depreciation and amortization	57,583	58,196	181,884	167,958
Interest expense	90	374	800	(436)
General and administrative expenses	0	0	0	0
Loss (gain) on derivatives and financial instruments, net	(9,906)	2,885	(18,785)	5,095
Loss (gain) on extinguishment of debt, net	0	0	0	0
Provision for loan losses, net	(1,345)	3,675	(2,874)	5,116
Impairment of assets	2,534	4,988	3,150	6,074
Other expenses	2,445	1,627	12,070	4,912
Income (loss) from continuing operations before income taxes and other items	219,769	154,533	531,955	555,431
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	(8,680)	2,056	(9,219)	9,858
Gain (loss) on real estate dispositions and acquisitions of controlling interests, net	272,334	(12)	293,628	436
Income (loss) from continuing operations	483,423	156,577	816,364	565,725
Net income (loss)	483,423	156,577	816,364	565,725
Total assets	9,845,405		9,845,405
Operating Segments | Outpatient Medical
Segment Reporting Information [Line Items]
Resident fees and services	0	0	0	0
Rental income	202,955	189,595	593,523	555,758
Interest income	852	98	2,552	284
Other income	2,040	2,265	7,019	6,939
Total revenues	205,847	191,958	603,094	562,981
Property operating expenses	62,778	62,204	186,426	179,266
Consolidated net operating income (loss)	143,069	129,754	416,668	383,715
Depreciation and amortization	66,503	65,923	199,783	196,383
Interest expense	(573)	2,313	2,455	9,569
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	7
Provision for loan losses, net	(5)	0	(9)	(2)
Impairment of assets	0	0	0	0
Other expenses	(500)	1,117	440	2,311
Income (loss) from continuing operations before income taxes and other items	77,644	60,400	213,999	175,447
Income tax (expense) benefit	0	0	0	0
Income (loss) from unconsolidated entities	395	(66)	4,840	(237)
Gain (loss) on real estate dispositions and acquisitions of controlling interests, net	(131)	(59)	8,062	(665)
Income (loss) from continuing operations	77,908	60,275	226,901	174,545
Net income (loss)	77,908	60,275	226,901	174,545
Total assets	7,553,112		7,553,112
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	38,951	29,834	89,777	43,705
Total revenues	38,951	29,834	89,777	43,705
Property operating expenses	4,691	4,035	13,688	12,106
Consolidated net operating income (loss)	34,260	25,799	76,089	31,599
Depreciation and amortization	0	0	0	0
Interest expense	130,791	139,487	389,283	402,158
General and administrative expenses	77,901	46,106	186,784	134,764
Loss (gain) on derivatives and financial instruments, net	0	0	0	0
Loss (gain) on extinguishment of debt, net	419	0	419	0
Provision for loan losses, net	0	0	0	0
Impairment of assets	0	0	0	0
Other expenses	380	611	6,149	4,307
Income (loss) from continuing operations before income taxes and other items	(175,231)	(160,405)	(506,546)	(509,630)
Income tax (expense) benefit	4,706	(4,584)	(2,586)	(11,132)
Income (loss) from unconsolidated entities	0	0	0	0
Gain (loss) on real estate dispositions and acquisitions of controlling interests, net	0	0	0	0
Income (loss) from continuing operations	(170,525)	(164,989)	(509,132)	(520,762)
Net income (loss)	(170,525)	$ (164,989)	(509,132)	$ (520,762)
Total assets	$ 2,654,932		$ 2,654,932

[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.