LOANS AND LEASES - Schedule of Age Analysis of Past Due Loans (Details) - USD ($) $ in Millions	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	$ 33,939	[1]	$ 32,323	[1]	$ 30,255
90 Days Past Due and Still Accruing	14		12
Non-accrual loans	159		107
Non-accrual with No ACL	43		25
30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	108		107
Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	281		226
Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	33,658		32,097
Total commercial loans and leases
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	21,164		20,496
90 Days Past Due and Still Accruing	0		1
Non-accrual loans	144		84
Non-accrual with No ACL	43		25
Total commercial loans and leases | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	38		33
Total commercial loans and leases | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	182		118
Total commercial loans and leases | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	20,982		20,378
Total commercial loans and leases | Commercial real estate
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	12,705		12,305
90 Days Past Due and Still Accruing	0		0
Non-accrual loans	88		42
Non-accrual with No ACL	24		18
Total commercial loans and leases | Commercial real estate | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	26		21
Total commercial loans and leases | Commercial real estate | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	114		63
Total commercial loans and leases | Commercial real estate | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	12,591		12,242
Total commercial loans and leases | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,550		7,482
90 Days Past Due and Still Accruing	0		0
Non-accrual loans	52		39
Non-accrual with No ACL	19		7
Total commercial loans and leases | Commercial and industrial | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	10		9
Total commercial loans and leases | Commercial and industrial | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	62		48
Total commercial loans and leases | Commercial and industrial | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,488		7,434
Total commercial loans and leases | Commercial leases
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	765		599
90 Days Past Due and Still Accruing	0		0
Non-accrual loans	2		3
Non-accrual with No ACL	0		0
Total commercial loans and leases | Commercial leases | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1		2
Total commercial loans and leases | Commercial leases | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3		5
Total commercial loans and leases | Commercial leases | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	762		594
Total commercial loans and leases | Other
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	144		110
90 Days Past Due and Still Accruing	0		1
Non-accrual loans	2		0
Non-accrual with No ACL	0		0
Total commercial loans and leases | Other | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1		1
Total commercial loans and leases | Other | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3		2
Total commercial loans and leases | Other | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	141		108
Total consumer loans
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	12,775		11,827
90 Days Past Due and Still Accruing	14		11
Non-accrual loans	15		23
Non-accrual with No ACL	0		0
Total consumer loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	70		74
Total consumer loans | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	99		108
Total consumer loans | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	12,676		11,719
Total consumer loans | Direct installment
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,676		2,741
90 Days Past Due and Still Accruing	2		1
Non-accrual loans	2		5
Non-accrual with No ACL	0		0
Total consumer loans | Direct installment | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	8		7
Total consumer loans | Direct installment | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	12		13
Total consumer loans | Direct installment | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,664		2,728
Total consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,986		6,640
90 Days Past Due and Still Accruing	9		7
Non-accrual loans	7		10
Non-accrual with No ACL	0		0
Total consumer loans | Residential mortgages | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	38		38
Total consumer loans | Residential mortgages | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	54		55
Total consumer loans | Residential mortgages | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,932		6,585
Total consumer loans | Indirect installment
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	739		1,149
90 Days Past Due and Still Accruing	1		1
Non-accrual loans	2		2
Non-accrual with No ACL	0		0
Total consumer loans | Indirect installment | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	16		19
Total consumer loans | Indirect installment | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	19		22
Total consumer loans | Indirect installment | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	720		1,127
Total consumer loans | Consumer lines of credit
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,374		1,297
90 Days Past Due and Still Accruing	2		2
Non-accrual loans	4		6
Non-accrual with No ACL	0		0
Total consumer loans | Consumer lines of credit | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	8		10
Total consumer loans | Consumer lines of credit | Past due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	14		18
Total consumer loans | Consumer lines of credit | Current
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	$ 1,360		$ 1,279

[1] Amount represents loans for which we have elected the fair value option. See Note 25.