VARIABLE INTEREST ENTITIES - Schedule of Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
LIHTC Investments
Variable Interest Entity [Line Items]
LIHTC investment included in other assets	$ 951	$ 793
LIHTC unfunded commitments included in other liabilities	491	428
Renewable Energy
Variable Interest Entity [Line Items]
Renewable energy investments included in other assets	$ 335	$ 220

Amount of investment in renewable energy projects.

No definition available.

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- Definition

Amount of investment in qualified affordable housing projects.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

+ Details

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- Definition

Amount of commitment or contingent commitments to qualified affordable housing project investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Details

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- Details

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