LOANS AND LEASES - Gross Charge-offs of Loans and Leases (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
2025	$ 10	$ 10	$ 18	$ 22
2024	19	22	53	57
2023	39	39	86	119
2022	11	22	73	61
2021	8	4	26	22
Prior	27	10	59	56
Revolver Gross Charge-offs	9	12	29	33
Revolver Converted to Term Loans Gross Charge-offs	14	10	37	32
Total	137	129	381	402
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	80	74	210	243
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	57	55	171	159
Commercial and industrial | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2025	4	1	6	1
2024	6	7	17	17
2023	30	30	54	60
2022	4	13	47	35
2021	3	1	8	12
Prior	3	2	16	6
Revolver Gross Charge-offs	9	8	27	28
Revolver Converted to Term Loans Gross Charge-offs	3	1	5	2
Total	62	63	180	161
Commercial real estate | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	2	2	11
2024	0	2	0	4
2023	0	0	0	30
2022	1	1	1	3
2021	0	0	1	0
Prior	16	0	16	24
Revolver Gross Charge-offs	0	4	1	4
Revolver Converted to Term Loans Gross Charge-offs	0	0	0	0
Total	17	9	21	76
Lease financing | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0	0	0
2024	0	1	1	2
2023	0	0	1	1
2022	1	1	4	2
2021	0	0	1	0
Prior	0	0	2	1
Revolver Gross Charge-offs	0	0	0	0
Revolver Converted to Term Loans Gross Charge-offs	0	0	0	0
Total	1	2	9	6
Residential mortgage | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0	0	0
2024	0	0	0	0
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
Prior	0	0	2	2
Revolver Gross Charge-offs	0	0	0	0
Revolver Converted to Term Loans Gross Charge-offs	0	0	0	0
Total	0	0	2	2
Automobile | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2025	2	2	2	2
2024	6	5	16	13
2023	4	4	13	13
2022	3	3	12	10
2021	3	1	9	4
Prior	1	1	3	3
Revolver Gross Charge-offs	0	0	0	0
Revolver Converted to Term Loans Gross Charge-offs	0	0	0	0
Total	19	16	55	45
Home equity | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0	0	0
2024	0	0	0	0
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
Prior	0	1	0	1
Revolver Gross Charge-offs	0	0	1	1
Revolver Converted to Term Loans Gross Charge-offs	2	1	4	4
Total	2	2	5	6
RV and marine | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0	0	0	0
2024	1	1	2	2
2023	2	1	6	3
2022	0	2	3	5
2021	1	1	4	3
Prior	3	2	10	8
Revolver Gross Charge-offs	0	0	0	0
Revolver Converted to Term Loans Gross Charge-offs	0	0	0	0
Total	7	7	25	21
Other consumer | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2025	4	5	8	8
2024	6	6	17	19
2023	3	4	12	12
2022	2	2	6	6
2021	1	1	3	3
Prior	4	4	10	11
Revolver Gross Charge-offs	0	0	0	0
Revolver Converted to Term Loans Gross Charge-offs	9	8	28	26
Total	$ 29	$ 30	$ 84	$ 85