NET OPERATING REVENUES - Sources of Net Operating Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Net operating revenues	$ 4,894	$ 4,557	$ 14,629	$ 12,725
Restatement Adjustment
Disaggregation of Revenue [Line Items]
Net operating revenues			21	3
Ambulatory Care
Disaggregation of Revenue [Line Items]
Net operating revenues	666	565	1,976	1,423
Conifer
Disaggregation of Revenue [Line Items]
Net operating revenues	314	325	943	962
Operating Segments | Hospital Operations
Disaggregation of Revenue [Line Items]
Net operating revenues	4,030	3,803	12,072	10,725
Operating Segments | Ambulatory Care
Disaggregation of Revenue [Line Items]
Net operating revenues	666	565	1,976	1,423
Operating Segments | Conifer
Disaggregation of Revenue [Line Items]
Net operating revenues	314	325	943	962
Inter-segment eliminations
Disaggregation of Revenue [Line Items]
Net operating revenues	(116)	(136)	(362)	(385)
Continuing Operations
Disaggregation of Revenue [Line Items]
Net operating revenues	4,894	4,557	14,629	12,725
Continuing Operations | Operating Segments | Hospital Operations
Disaggregation of Revenue [Line Items]
Net operating revenues	4,030	3,803	12,072	10,725
Continuing Operations | Operating Segments | Hospital Operations | Other Revenues
Disaggregation of Revenue [Line Items]
Net operating revenues	319	295	929	848
Continuing Operations | Operating Segments | Ambulatory Care
Disaggregation of Revenue [Line Items]
Net operating revenues	666	565	1,976	1,423
Continuing Operations | Operating Segments | Conifer
Disaggregation of Revenue [Line Items]
Net operating revenues	314	325	943	962
Continuing Operations | Inter-segment eliminations
Disaggregation of Revenue [Line Items]
Net operating revenues	(116)	(136)	(362)	(385)
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Medicare
Disaggregation of Revenue [Line Items]
Net operating revenues	616	662	2,001	1,964
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Medicaid
Disaggregation of Revenue [Line Items]
Net operating revenues	336	251	883	791
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Managed care
Disaggregation of Revenue [Line Items]
Net operating revenues	2,567	2,374	7,592	6,519
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Uninsured
Disaggregation of Revenue [Line Items]
Net operating revenues	33	50	140	112
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Indemnity and other
Disaggregation of Revenue [Line Items]
Net operating revenues	159	171	527	491
Continuing Operations | Acute Care Hospitals and Related Outpatient Facilities | Operating Segments | Hospital Operations | Total
Disaggregation of Revenue [Line Items]
Net operating revenues	$ 3,711	$ 3,508	$ 11,143	$ 9,877