DERIVATIVES ACTIVITIES - Cumulative Basis Adjustment (Details) $ in Millions	Sep. 30, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Debt securities AFS, carrying amount of hedged asset/liability	$ 80,244
Debt securities AFS, cumulative fair value hedging adjustment included in the carrying amount, active	(326)
Debt securities AFS, cumulative fair value hedging adjustment included in the carrying amount, de-designated	421
Long-term debt, carrying amount of hedged asset/liability	154,540
Long-term debt, cumulative fair value hedging adjustment included in the carrying amount, active	(775)
Long-term debt, cumulative fair value hedging adjustment included in the carrying amount, de-designated	$ 1,218

No definition available.

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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- Definition

Amount of asset hedged in fair value hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of liability hedged in fair value hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

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