GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance	$ 3,897	$ 3,281
Acquisitions	31	616
Ending balance	3,928	3,897
Retail
Goodwill [Roll Forward]
Beginning balance	1,535	1,059
Acquisitions	0	476
Ending balance	1,535	1,535
Group and Specialty
Goodwill [Roll Forward]
Beginning balance	261	261
Acquisitions	0	0
Ending balance	261	261
Healthcare Services
Goodwill [Roll Forward]
Beginning balance	2,101	1,961
Acquisitions	31	140
Ending balance	$ 2,132	$ 2,101

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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