GOODWILL AND INTANGIBLE ASSETS - Goodwill Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance	$ 6,923	$ 6,887
Business acquisitions	118	59
Adjustments	3	(23)
Ending balance	7,044	6,923
Consumer Banking
Goodwill [Roll Forward]
Beginning balance	2,172	2,136
Business acquisitions	83	59
Adjustments	3	(23)
Ending balance	2,258	2,172
Commercial Banking
Goodwill [Roll Forward]
Beginning balance	4,751	4,751
Business acquisitions	35	0
Adjustments	0	0
Ending balance	$ 4,786	$ 4,751

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
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-Section 45
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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
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-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e961-128460

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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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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