Segment Reporting - Summary Information for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	[1]
Segment Reporting Information [Line Items]
Resident fees and services	$ 1,360,274	$ 1,131,685
Rental income	417,652	384,059
Interest income	52,664	36,405
Other income	29,151	8,580
Total revenues	1,859,741	1,560,729
Property operating expenses	1,096,913	957,753
Consolidated net operating income (loss)	762,828	602,976
Depreciation and amortization	365,863	339,112
Interest expense	147,318	144,403
General and administrative expenses	53,318	44,371
Loss (gain) on derivatives and financial instruments, net	(3,054)	930
Loss (gain) on extinguishment of debt, net	6	5
Provision for loan losses, net	1,014	777
Impairment of assets	43,331	12,629
Other expenses	14,131	22,745
Income (loss) from continuing operations before income taxes and other items	140,901	38,004
Income tax (expense) benefit	(6,191)	(3,045)
Income (loss) from unconsolidated entities	(7,783)	(7,071)
Gain (loss) on real estate dispositions, net	4,707	747
Income (loss) from continuing operations	131,634	28,635
Net income (loss)	131,634	28,635
Total assets	44,553,585		$ 44,012,166
Seniors Housing Operating
Segment Reporting Information [Line Items]
Rental income	130,565	108,915
Operating Segments | Seniors Housing Operating
Segment Reporting Information [Line Items]
Resident fees and services	1,360,274	1,131,685
Rental income	0	0
Interest income	5,023	2,551
Other income	1,463	2,445
Total revenues	1,366,760	1,136,681
Property operating expenses	1,019,347	883,784
Consolidated net operating income (loss)	347,413	252,897
Depreciation and amortization	236,796	220,407
Interest expense	11,186	11,487
General and administrative expenses	0	0
Loss (gain) on derivatives and financial instruments, net	0	0
Loss (gain) on extinguishment of debt, net	6	0
Provision for loan losses, net	1,568	(73)
Impairment of assets	43,331	12,629
Other expenses	8,757	17,579
Income (loss) from continuing operations before income taxes and other items	45,769	(9,132)
Income tax (expense) benefit	0	0
Income (loss) from unconsolidated entities	(4,267)	(15,589)
Gain (loss) on real estate dispositions, net	4,602	833
Income (loss) from continuing operations	46,104	(23,888)
Net income (loss)	46,104	(23,888)
Total assets	25,009,470
Operating Segments | Triple-net
Segment Reporting Information [Line Items]
Resident fees and services	0	0
Rental income	221,744	202,419
Interest income	46,789	33,763
Other income	1,199	1,883
Total revenues	269,732	238,065
Property operating expenses	10,817	11,723
Consolidated net operating income (loss)	258,915	226,342
Depreciation and amortization	62,535	54,528
Interest expense	358	(15)
General and administrative expenses	0	0
Loss (gain) on derivatives and financial instruments, net	(3,054)	930
Loss (gain) on extinguishment of debt, net	0	0
Provision for loan losses, net	(567)	850
Impairment of assets	0	0
Other expenses	1,205	2,467
Income (loss) from continuing operations before income taxes and other items	198,438	167,582
Income tax (expense) benefit	0	0
Income (loss) from unconsolidated entities	(3,153)	8,432
Gain (loss) on real estate dispositions, net	26	520
Income (loss) from continuing operations	195,311	176,534
Net income (loss)	195,311	176,534
Total assets	9,883,758
Operating Segments | Outpatient Medical
Segment Reporting Information [Line Items]
Resident fees and services	0	0
Rental income	195,908	181,640
Interest income	852	91
Other income	2,402	3,100
Total revenues	199,162	184,831
Property operating expenses	62,463	58,365
Consolidated net operating income (loss)	136,699	126,466
Depreciation and amortization	66,532	64,177
Interest expense	1,718	4,104
General and administrative expenses	0	0
Loss (gain) on derivatives and financial instruments, net	0	0
Loss (gain) on extinguishment of debt, net	0	5
Provision for loan losses, net	13	0
Impairment of assets	0	0
Other expenses	609	547
Income (loss) from continuing operations before income taxes and other items	67,827	57,633
Income tax (expense) benefit	0	0
Income (loss) from unconsolidated entities	(363)	86
Gain (loss) on real estate dispositions, net	79	(606)
Income (loss) from continuing operations	67,543	57,113
Net income (loss)	67,543	57,113
Total assets	7,414,657
Non-segment/Corporate
Segment Reporting Information [Line Items]
Resident fees and services	0	0
Rental income	0	0
Interest income	0	0
Other income	24,087	1,152
Total revenues	24,087	1,152
Property operating expenses	4,286	3,881
Consolidated net operating income (loss)	19,801	(2,729)
Depreciation and amortization	0	0
Interest expense	134,056	128,827
General and administrative expenses	53,318	44,371
Loss (gain) on derivatives and financial instruments, net	0	0
Loss (gain) on extinguishment of debt, net	0	0
Provision for loan losses, net	0	0
Impairment of assets	0	0
Other expenses	3,560	2,152
Income (loss) from continuing operations before income taxes and other items	(171,133)	(178,079)
Income tax (expense) benefit	(6,191)	(3,045)
Income (loss) from unconsolidated entities	0	0
Gain (loss) on real estate dispositions, net	0	0
Income (loss) from continuing operations	(177,324)	(181,124)
Net income (loss)	(177,324)	$ (181,124)
Total assets	$ 2,245,700

[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.