PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Equipment at cost	$ 13,971	$ 13,971
Total property and equipment cost	1,441,300	1,320,700
Accumulated depreciation	(836,899)	(754,739)
Total property and equipment	604,401	565,961
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	250	250
Medical equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	714,400	649,034
Computer and office equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	127,540	119,467
Software costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	47,286	36,015
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 537,853	$ 501,963