LOANS AND LEASES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value:	$ 1,219	$ 497
Other loans held for sale	101	221
Level 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value:	1,219	497
Other loans held for sale	0	0
Level 2 \| Residential loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value:	967	326
Level 2 \| Commercial loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value:	252	171
TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sales		78
Gain (loss) on sales of loans		17
Residential mortgages \| TDR Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sales		49
Retail \| Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral for FHLB borrowed funds	25,600	24,900
Loans pledged as collateral to support the contingent ability to borrow at the FRB discount window	16,800	18,100
Retail \| Education loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	457	862
Retail \| Automobile loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases		153
Retail \| Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sales		254
Retail \| Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sales		29
Commercial Portfolio Segment \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sales	$ 553	$ 603

The amount of other loans receivable that will be sold to other entities.

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+ References

No definition available.

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The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

+ References

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The face amount of loans that will be sold to other entities.

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- Definition

The cash outflow for the purchase of amounts due from customers, clients, lessees, borrowers, or others under the terms of its agreements therewith.

+ References

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of other debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

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- Definition

The cash inflow associated with the sale of receivables arising from the financing of goods and services.

+ References

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