SEGMENT INFORMATION - Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Rental income	$ 350,982	$ 383,052	$ 1,051,721	$ 1,100,003
Income from loans and investments	12,672	28,729	33,271	65,404
Interest and other income	489	417	2,191	1,343
Total revenues	1,037,276	976,078	3,077,768	2,805,563
Less:
Interest and other income	489	417	2,191	1,343
Property-level operating expenses	569,826	523,328	1,686,906	1,504,123
Office building and other services costs	1,750	522	4,473	1,798
NOI	465,211	451,811	1,384,198	1,298,299
Interest and other income	489	417	2,191	1,343
Interest expense	(119,413)	(108,816)	(344,158)	(329,634)
Depreciation and amortization	(301,481)	(313,596)	(873,620)	(878,444)
General, administrative and professional fees	(35,421)	(30,259)	(111,334)	(101,156)
Loss on extinguishment of debt, net	(574)	(29,792)	(581)	(56,808)
Transaction expenses and deal costs	(4,782)	(22,662)	(37,852)	(28,000)
Allowance on loans receivable and investments	63	60	179	9,021
Other	(9,162)	(33,673)	(30,088)	(10,755)
Income (loss) from unconsolidated entities	1,970	2,772	(3,346)	7,289
Gain on real estate dispositions	136	150,292	2,557	194,083
Income tax benefit (expense)	6,027	(3,780)	14,307	(9,574)
Income from continuing operations	3,063	62,774	2,453	95,664
Net income	3,063	62,774	2,453	95,664
Net income attributable to noncontrolling interests	1,807	2,094	4,881	5,802
Net income (loss) attributable to common stockholders	1,256	60,680	(2,428)	89,862
Resident fees and services
Revenues:
Other revenues	668,583	558,039	1,977,760	1,622,641
Office building and other services revenue
Revenues:
Other revenues	4,550	5,841	12,825	16,172
Operating Segments
Less:
Office building and other services costs			4,473
Operating Segments | Triple-Net Leased Properties
Revenues:
Rental income	150,115	181,379	451,073	500,487
Income from loans and investments	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	150,115	181,379	451,073	500,487
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	3,756	3,268	11,349	12,525
Office building and other services costs	0	0	0	0
NOI	146,359	178,111	439,724	487,962
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 | Office building and other services revenue
Revenues:
Other revenues	0	0	0	0
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	668,583	558,039	1,977,760	1,622,641
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	499,972	453,659	1,482,948	1,296,301
Office building and other services costs	0	0	0	0
NOI	168,611	104,380	494,812	326,340
Interest and other income	0	0	0	0
Operating Segments | SHOP | Resident fees and services
Revenues:
Other revenues	668,583	558,039	1,977,760	1,622,641
Operating Segments | SHOP | Office building and other services revenue
Revenues:
Other revenues	0	0	0	0
Operating Segments | Office Operations
Revenues:
Rental income	200,867	201,673	600,648	599,516
Income from loans and investments	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	201,414	204,545	602,482	607,272
Less:
Interest and other income	0	0	0	0
Property-level operating expenses	66,098	66,401	192,609	195,297
Office building and other services costs	0	522	0	1,798
NOI	135,316	137,622	409,873	410,177
Interest and other income	0	0	0	0
Operating Segments | Office Operations | Resident fees and services
Revenues:
Other revenues	0	0	0	0
Operating Segments | Office Operations | Office building and other services revenue
Revenues:
Other revenues	547	2,872	1,834	7,756
Non-Segment
Revenues:
Rental income	0	0	0	0
Income from loans and investments	12,672	28,729	33,271	65,404
Interest and other income	489	417	2,191	1,343
Total revenues	17,164	32,115	46,453	75,163
Less:
Interest and other income	489	417	2,191	1,343
Property-level operating expenses	0	0	0	0
Office building and other services costs	1,750	0	4,473	0
NOI	14,925	31,698	39,789	73,820
Interest and other income	489	417	2,191	1,343
Non-Segment | Resident fees and services
Revenues:
Other revenues	0	0	0	0
Non-Segment | Office building and other services revenue
Revenues:
Other revenues	$ 4,003	$ 2,969	$ 10,991	$ 8,416