LOANS AND LEASES - Troubled Debt Restructurings (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021 USD ($) Contract	Sep. 30, 2020 USD ($) Contract	Sep. 30, 2021 USD ($) Contract	Sep. 30, 2020 USD ($) Contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	36	36	102	147
Pre- Modification Outstanding Recorded Investment	$ 4	$ 4	$ 26	$ 18
Post- Modification Outstanding Recorded Investment	$ 4	$ 4	$ 25	$ 14
Total Commercial Loans and Leases [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	9	11	30	43
Pre- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 21	$ 11
Post- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 20	$ 8
Total Commercial Loans and Leases [Member] \| Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	5	7	21	23
Pre- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 20	$ 8
Post- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 20	$ 6
Total Commercial Loans and Leases [Member] \| Commercial and Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	3	4	8	19
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 1	$ 3
Post- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 0	$ 2
Total Commercial Loans and Leases [Member] \| Other [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	1	0	1	1
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 0	$ 0
Post- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 0	$ 0
Total Consumer Loan [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	27	25	72	104
Pre- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 5	$ 7
Post- Modification Outstanding Recorded Investment	$ 2	$ 2	$ 5	$ 6
Total Consumer Loan [Member] \| Direct Installment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	8	14	26	50
Pre- Modification Outstanding Recorded Investment	$ 0	$ 1	$ 1	$ 3
Post- Modification Outstanding Recorded Investment	$ 0	$ 1	$ 1	$ 3
Total Consumer Loan [Member] \| Residential Mortgages [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	12	2	15	18
Pre- Modification Outstanding Recorded Investment	$ 2	$ 1	$ 2	$ 3
Post- Modification Outstanding Recorded Investment	$ 2	$ 1	$ 2	$ 2
Total Consumer Loan [Member] \| Consumer Lines of Credit [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| Contract	7	9	31	36
Pre- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 2	$ 1
Post- Modification Outstanding Recorded Investment	$ 0	$ 0	$ 2	$ 1

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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