ACQUISITIONS AND DIVESTITURES - Narrative (Details) $ in Millions			2 Months Ended	3 Months Ended		7 Months Ended	12 Months Ended
	Aug. 09, 2018 USD ($)	Aug. 08, 2018 USD ($)	Feb. 20, 2020 USD ($) primary_care_center	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Aug. 08, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Disclosures by Disposal Groups [Line Items]
Purchase price allocated to goodwill							$ 31	$ 616
Disposed of by sale | KMG America Corporation
Disclosures by Disposal Groups [Line Items]
Cash contribution from parent to disposal group to fund transaction	$ 190
Statutory capital transferred with sale	160
Loss, including transaction costs, on disposal	786
Tax benefit on disposal transaction	$ 452
Cash transferred to third party prior to sale		$ 245
Disposal group revenues						$ 182			$ 261
Disposal group income						$ 47			$ 117
Enclara | Subsequent Event
Disclosures by Disposal Groups [Line Items]
Cash consideration for acquisition			$ 707
MCCI Holdings LLC
Disclosures by Disposal Groups [Line Items]
Cash consideration for acquisition					$ 169
Purchase price allocated to goodwill					483
Purchase price allocated to other intangible assets					80
Purchase price allocated to net tangible assets					$ 24
Estimated weighted average useful life of acquired intangible assets (in years)					8 years
Family Physicians Group
Disclosures by Disposal Groups [Line Items]
Cash consideration for acquisition				$ 185
Purchase price allocated to goodwill				133
Purchase price allocated to other intangible assets				38
Purchase price allocated to net tangible assets				$ 14
Estimated weighted average useful life of acquired intangible assets (in years)				4 years 10 months 24 days
WCAS | Subsequent Event
Disclosures by Disposal Groups [Line Items]
Expected number of payor-agnostic, senior-focused primary care centers to be opened by strategic partnership | primary_care_center			50
Expected time frame for opening primary care centers			3 years
Value of partnership entity			$ 600
Time frame for put and call option activity per partnership agreement, minimum			5 years
Time frame for put and call option activity per partnership agreement, maximum			10 years
MCCI Holdings LLC
Disclosures by Disposal Groups [Line Items]
Note receivable					$ 383