SEGMENT INFORMATION - Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues:
Rental income	$ 370,162	$ 348,638	$ 722,905	$ 700,739
Income from loans and investments	6,554	10,752	20,143	20,599
Interest and other income	1,032	1,166	2,775	1,702
Total revenues	1,106,358	1,022,938	2,183,603	2,040,492
Less:
Interest and other income	1,032	1,166	2,775	1,702
Property-level operating expenses	622,818	574,359	1,230,749	1,117,080
Third party capital management expenses	1,436	1,410	3,142	2,723
NOI	481,072	446,003	946,937	918,987
Interest and other income	1,032	1,166	2,775	1,702
Interest expense	(143,265)	(113,951)	(271,340)	(224,745)
Depreciation and amortization	(304,689)	(283,075)	(586,808)	(572,139)
General, administrative and professional fees	(34,399)	(32,915)	(79,197)	(75,913)
Transaction expenses and deal costs	(3,069)	(13,078)	(4,455)	(33,070)
Allowance on loans receivable and investments	12,065	62	20,129	116
Gain on foreclosure of real estate	29,127	0	29,127	0
Other	17,959	(48,116)	10,197	(20,926)
Income (loss) from unconsolidated entities	31,254	(1,047)	25,631	(5,316)
Gain on real estate dispositions	1,405	(34)	11,606	2,421
Income tax benefit	9,773	3,790	12,575	8,280
Income (loss) from continuing operations	105,066	(41,202)	123,978	(610)
Net income (loss)	105,066	(41,202)	123,978	(610)
Net income attributable to noncontrolling interests	1,613	1,214	3,008	3,074
Net income (loss) attributable to common stockholders	103,453	(42,416)	120,970	(3,684)
Resident fees and services
Revenues:
Other revenues	724,614	658,056	1,429,607	1,309,177
Third party capital management revenues
Revenues:
Other revenues	3,996	4,326	8,173	8,275
Operating Segments
Less:
Third party capital management expenses			3,142
Operating Segments | Triple-Net Leased Properties
Revenues:
Rental income	154,355	149,397	304,094	300,958
Income from loans and investments	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	154,355	149,397	304,094	300,958
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	3,537	3,585	7,333	7,593
Third party capital management expenses	0	0	0	0
NOI	150,818	145,812	296,761	293,365
Interest and other income	0	0	0	0
Operating Segments | Triple-Net Leased Properties | Resident fees and services
Revenues:
Other revenues	0	0	0	0
Operating Segments | Triple-Net Leased Properties | Third party capital management revenues
Revenues:
Other revenues	0	0	0	0
Operating Segments | Outpatient Medical and Research Portfolio
Revenues:
Rental income	215,807	199,241	418,811	399,781
Income from loans and investments	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	216,366	199,911	419,998	401,068
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	72,171	63,328	139,084	126,511
Third party capital management expenses	0	0	0
NOI	144,195	136,583	280,914	274,557
Interest and other income	0	0	0	0
Operating Segments | Outpatient Medical and Research Portfolio | Resident fees and services
Revenues:
Other revenues	0	0	0	0
Operating Segments | Outpatient Medical and Research Portfolio | Third party capital management revenues
Revenues:
Other revenues	559	670	1,187	1,287
Operating Segments | SHOP
Revenues:
Rental income	0	0	0	0
Income from loans and investments	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	724,614	658,056	1,429,607	1,309,177
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	547,110	507,446	1,084,332	982,976
Third party capital management expenses	0	0	0	0
NOI	177,504	150,610	345,275	326,201
Interest and other income	0	0	0	0
Operating Segments | SHOP | Resident fees and services
Revenues:
Other revenues	724,614	658,056	1,429,607	1,309,177
Operating Segments | SHOP | Third party capital management revenues
Revenues:
Other revenues	0	0	0	0
Non-Segment
Revenues:
Rental income	0	0	0	0
Income from loans and investments	6,554	10,752	20,143	20,599
Interest and other income	1,032	1,166	2,775	1,702
Total revenues	11,023	15,574	29,904	29,289
Less:
Interest and other income	1,032	1,166	2,775	1,702
Property-level operating expenses	0	0	0	0
Third party capital management expenses	1,436	1,410	3,142	2,723
NOI	8,555	12,998	23,987	24,864
Interest and other income	1,032	1,166	2,775	1,702
Non-Segment | Resident fees and services
Revenues:
Other revenues	0	0	0	0
Non-Segment | Third party capital management revenues
Revenues:
Other revenues	$ 3,437	$ 3,656	$ 6,986	$ 6,988