SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)		12 Months Ended
	Jan. 01, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Significant Accounting Policies [Line Items]
Impairment of indefinite-lived intangible assets		$ 55,000,000	$ 0	$ 0
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		$ 2,300,000,000	2,000,000,000
Typical term (in years) of short-duration employer-group prepaid health services policies		1 year
Goodwill		$ 9,550,000,000	9,142,000,000	11,092,000,000
Goodwill impairment loss		0	0	$ 0
Value Creation Initiatives
Significant Accounting Policies [Line Items]
Restructuring and impairment charge		436,000,000	473,000,000
Assets held for abandonment		237,000,000	248,000,000
Severance costs		199,000,000	116,000,000
Exit From Employer Group Commercial Medical Products Business
Significant Accounting Policies [Line Items]
Severance costs		70,000,000
Asset impairment charges		91,000,000
Impairment of indefinite-lived intangible assets		55,000,000
Home Solutions Reporting Unit
Significant Accounting Policies [Line Items]
Goodwill		4,400,000,000
Provider reporting unit
Significant Accounting Policies [Line Items]
Goodwill		$ 1,200,000,000
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		$ 357,000,000	$ 291,000,000
Medicare Supplement | 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