SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Nov. 02, 2017
Significant Accounting Policies [Line Items]
Health services term		1 year
Number of days notice for employer group to cancel short-duration prepaid health services policies		30 days
Consumer discounts on brand name prescription drugs		50.00%
Pharmaceutical rebates		$ 2,000,000,000	$ 2,000,000,000
Typical term (in years) of short-duration employer-group prepaid health services policies		1 year
Goodwill		$ 9,142,000,000	11,092,000,000	$ 4,447,000,000
Goodwill impairment loss		0	0	0
Value Creation Initiatives
Significant Accounting Policies [Line Items]
Restructuring and impairment charge		473,000,000
Assets held for abandonment		248,000,000
Severance costs		116,000,000
Home Solutions Reporting Unit
Significant Accounting Policies [Line Items]
Goodwill		4,300,000,000
Provider reporting unit
Significant Accounting Policies [Line Items]
Goodwill		$ 1,100,000,000
Equipment | Minimum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		3 years
Equipment | Maximum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		10 years
Computer software | Minimum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		3 years
Computer software | Maximum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		5 years
Building | Minimum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		10 years
Building | Maximum
Significant Accounting Policies [Line Items]
Long-lived assets estimated useful life (in years)		20 years
Services
Significant Accounting Policies [Line Items]
Accounts receivable		$ 291,000,000	$ 475,000,000
Medicare Supplement Product | Revenue Benchmark | Product Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk (percent)		1.00%
Reinsurance Policy, Type [Axis]: CMS brand name prescription drug discounts | Minimum
Significant Accounting Policies [Line Items]
Settlement period after close		14 months
Reinsurance Policy, Type [Axis]: CMS brand name prescription drug discounts | Maximum
Significant Accounting Policies [Line Items]
Settlement period after close		18 months
Reinsurance Policy, Type [Axis]: CMS reinsurance subsidies and discounts
Significant Accounting Policies [Line Items]
Settlement period after close		9 months
US Risk Corridor Premium Stabilization Program
Significant Accounting Policies [Line Items]
Litigation recoveries sought					$ 611,000,000
Payment received upon judgement	$ 609,000,000			609,000,000
Related legal fees and expenses				31,000,000
Health Care Reform
Significant Accounting Policies [Line Items]
Payment of annual health insurance industry fee				$ 1,180,000,000