LOANS AND LEASES - Schedule of Origination Year (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	$ 5,418.0		$ 5,486.0
Fiscal year before current fiscal year	4,916.0		6,624.0
Two years before current fiscal year	5,924.0		6,015.0
Three years before current fiscal year	5,165.0		3,537.0
Four years before current fiscal year	2,997.0		2,255.0
Prior	6,092.0		5,148.0
Revolving Loans Amortized Cost Basis	3,427.0		3,258.0
Total Loans and Leases	33,939.0	[1]	32,323.0	[1]	$ 30,255.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.4		0.8
Fiscal year before current fiscal year, charge-off	7.4		5.2
Two years before current fiscal year, charge-off	7.7		5.2
Three years before current fiscal year, charge-off	20.5		2.4
Four years before current fiscal year, charge-off	17.0		2.7
Prior, charge-off	28.8		64.8
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	81.8		81.1
Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	33,658.0		32,097.0
Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	281.0		226.0
Commercial and industrial
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total Loans and Leases, charge-off	31.9
Total commercial loans and leases
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	3,002.0		3,371.0
Fiscal year before current fiscal year	3,089.0		3,762.0
Two years before current fiscal year	3,571.0		3,449.0
Three years before current fiscal year	2,897.0		2,238.0
Four years before current fiscal year	1,874.0		1,726.0
Prior	4,447.0		3,740.0
Revolving Loans Amortized Cost Basis	2,284.0		2,210.0
Total Loans and Leases	21,164.0		20,496.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total Loans and Leases, charge-off	64.0		68.1		23.4
Total commercial loans and leases | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	20,982.0		20,378.0
Total commercial loans and leases | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	182.0		118.0
Total commercial loans and leases | Commercial real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,408.0		1,523.0
Fiscal year before current fiscal year	1,687.0		2,226.0
Two years before current fiscal year	2,321.0		2,401.0
Three years before current fiscal year	2,079.0		1,598.0
Four years before current fiscal year	1,362.0		1,295.0
Prior	3,611.0		3,012.0
Revolving Loans Amortized Cost Basis	237.0		250.0
Total Loans and Leases	12,705.0		12,305.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.0		0.2
Fiscal year before current fiscal year, charge-off	0.8		0.4
Two years before current fiscal year, charge-off	1.0		0.4
Three years before current fiscal year, charge-off	15.0		0.7
Four years before current fiscal year, charge-off	10.5		0.2
Prior, charge-off	11.3		10.5
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	38.6		12.4		12.5
Total commercial loans and leases | Commercial real estate | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	12,591.0		12,242.0
Total commercial loans and leases | Commercial real estate | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	114.0		63.0
Total commercial loans and leases | Commercial real estate | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,405.0		1,508.0
Fiscal year before current fiscal year	1,661.0		2,133.0
Two years before current fiscal year	2,025.0		2,298.0
Three years before current fiscal year	1,984.0		1,449.0
Four years before current fiscal year	1,200.0		1,131.0
Prior	3,235.0		2,711.0
Revolving Loans Amortized Cost Basis	197.0		230.0
Total Loans and Leases	11,707.0		11,460.0
Total commercial loans and leases | Commercial real estate | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1.0		10.0
Fiscal year before current fiscal year	10.0		66.0
Two years before current fiscal year	177.0		76.0
Three years before current fiscal year	52.0		136.0
Four years before current fiscal year	107.0		105.0
Prior	181.0		197.0
Revolving Loans Amortized Cost Basis	37.0		5.0
Total Loans and Leases	565.0		595.0
Total commercial loans and leases | Commercial real estate | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	2.0		5.0
Fiscal year before current fiscal year	16.0		27.0
Two years before current fiscal year	119.0		27.0
Three years before current fiscal year	43.0		13.0
Four years before current fiscal year	55.0		59.0
Prior	195.0		104.0
Revolving Loans Amortized Cost Basis	3.0		15.0
Total Loans and Leases	433.0		250.0
Total commercial loans and leases | Commercial and industrial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,251.0		1,555.0
Fiscal year before current fiscal year	1,149.0		1,398.0
Two years before current fiscal year	1,142.0		962.0
Three years before current fiscal year	754.0		586.0
Four years before current fiscal year	481.0		406.0
Prior	791.0		678.0
Revolving Loans Amortized Cost Basis	1,982.0		1,897.0
Total Loans and Leases	7,550.0		7,482.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.1		0.1
Fiscal year before current fiscal year, charge-off	3.9		0.3
Two years before current fiscal year, charge-off	1.5		1.0
Three years before current fiscal year, charge-off	1.8		1.0
Four years before current fiscal year, charge-off	6.0		2.2
Prior, charge-off	7.6		46.6
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	20.9		51.2		7.4
Total commercial loans and leases | Commercial and industrial | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	7,488.0		7,434.0
Total commercial loans and leases | Commercial and industrial | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	62.0		48.0
Total commercial loans and leases | Commercial and industrial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,241.0		1,509.0
Fiscal year before current fiscal year	1,079.0		1,369.0
Two years before current fiscal year	1,074.0		844.0
Three years before current fiscal year	647.0		575.0
Four years before current fiscal year	461.0		370.0
Prior	669.0		585.0
Revolving Loans Amortized Cost Basis	1,861.0		1,773.0
Total Loans and Leases	7,032.0		7,025.0
Total commercial loans and leases | Commercial and industrial | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	6.0		12.0
Fiscal year before current fiscal year	20.0		3.0
Two years before current fiscal year	57.0		56.0
Three years before current fiscal year	74.0		2.0
Four years before current fiscal year	12.0		12.0
Prior	63.0		35.0
Revolving Loans Amortized Cost Basis	41.0		35.0
Total Loans and Leases	273.0		155.0
Total commercial loans and leases | Commercial and industrial | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	4.0		34.0
Fiscal year before current fiscal year	50.0		26.0
Two years before current fiscal year	11.0		62.0
Three years before current fiscal year	33.0		9.0
Four years before current fiscal year	8.0		24.0
Prior	59.0		58.0
Revolving Loans Amortized Cost Basis	80.0		89.0
Total Loans and Leases	245.0		302.0
Total commercial loans and leases | Commercial leases
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	331.0		254.0
Fiscal year before current fiscal year	191.0		138.0
Two years before current fiscal year	108.0		86.0
Three years before current fiscal year	64.0		54.0
Four years before current fiscal year	31.0		25.0
Prior	40.0		42.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	765.0		599.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.0		0.0
Fiscal year before current fiscal year, charge-off	0.0		0.0
Two years before current fiscal year, charge-off	0.0		0.0
Three years before current fiscal year, charge-off	0.0		0.0
Four years before current fiscal year, charge-off	0.0		0.0
Prior, charge-off	0.3		0.0
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	0.3		0.0		0.1
Total commercial loans and leases | Commercial leases | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	762.0		594.0
Total commercial loans and leases | Commercial leases | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	3.0		5.0
Total commercial loans and leases | Commercial leases | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	331.0		247.0
Fiscal year before current fiscal year	184.0		134.0
Two years before current fiscal year	106.0		82.0
Three years before current fiscal year	60.0		47.0
Four years before current fiscal year	26.0		24.0
Prior	39.0		41.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	746.0		575.0
Total commercial loans and leases | Commercial leases | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0.0		0.0
Fiscal year before current fiscal year	1.0		1.0
Two years before current fiscal year	0.0		0.0
Three years before current fiscal year	0.0		0.0
Four years before current fiscal year	0.0		0.0
Prior	1.0		1.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	2.0		2.0
Total commercial loans and leases | Commercial leases | Substandard
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0.0		7.0
Fiscal year before current fiscal year	6.0		3.0
Two years before current fiscal year	2.0		4.0
Three years before current fiscal year	4.0		7.0
Four years before current fiscal year	5.0		1.0
Prior	0.0		0.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	17.0		22.0
Total commercial loans and leases | Other
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	12.0		39.0
Fiscal year before current fiscal year	62.0		0.0
Two years before current fiscal year	0.0		0.0
Three years before current fiscal year	0.0		0.0
Four years before current fiscal year	0.0		0.0
Prior	5.0		8.0
Revolving Loans Amortized Cost Basis	65.0		63.0
Total Loans and Leases	144.0		110.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.0		0.0
Fiscal year before current fiscal year, charge-off	0.0		0.0
Two years before current fiscal year, charge-off	0.0		0.0
Three years before current fiscal year, charge-off	0.0		0.0
Four years before current fiscal year, charge-off	0.0		0.0
Prior, charge-off	4.2		4.5
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	4.2		4.5		3.4
Total commercial loans and leases | Other | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	141.0		108.0
Total commercial loans and leases | Other | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	3.0		2.0
Total commercial loans and leases | Other | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	12.0		39.0
Fiscal year before current fiscal year	62.0		0.0
Two years before current fiscal year	0.0		0.0
Three years before current fiscal year	0.0		0.0
Four years before current fiscal year	0.0		0.0
Prior	5.0		8.0
Revolving Loans Amortized Cost Basis	65.0		63.0
Total Loans and Leases	144.0		110.0
Total consumer loans
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	2,416.0		2,115.0
Fiscal year before current fiscal year	1,827.0		2,862.0
Two years before current fiscal year	2,353.0		2,566.0
Three years before current fiscal year	2,268.0		1,299.0
Four years before current fiscal year	1,123.0		529.0
Prior	1,645.0		1,408.0
Revolving Loans Amortized Cost Basis	1,143.0		1,048.0
Total Loans and Leases	12,775.0		11,827.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total Loans and Leases, charge-off	17.8		13.0		8.3
Total consumer loans | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	12,676.0		11,719.0
Total consumer loans | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total Loans and Leases	99.0		108.0
Total consumer loans | Direct installment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	346.0		340.0
Fiscal year before current fiscal year	278.0		713.0
Two years before current fiscal year	624.0		784.0
Three years before current fiscal year	684.0		393.0
Four years before current fiscal year	342.0		137.0
Prior	402.0		374.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	2,676.0		2,741.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.0		0.0
Fiscal year before current fiscal year, charge-off	0.2		0.2
Two years before current fiscal year, charge-off	0.3		0.1
Three years before current fiscal year, charge-off	0.2		0.1
Four years before current fiscal year, charge-off	0.0		0.0
Prior, charge-off	1.1		0.2
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	1.8		0.6		0.6
Total consumer loans | Direct installment | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	346.0		340.0
Fiscal year before current fiscal year	277.0		712.0
Two years before current fiscal year	621.0		784.0
Three years before current fiscal year	683.0		392.0
Four years before current fiscal year	341.0		136.0
Prior	396.0		364.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	2,664.0		2,728.0
Total consumer loans | Direct installment | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0.0		0.0
Fiscal year before current fiscal year	1.0		1.0
Two years before current fiscal year	3.0		0.0
Three years before current fiscal year	1.0		1.0
Four years before current fiscal year	1.0		1.0
Prior	6.0		10.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	12.0		13.0
Total consumer loans | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,665.0		1,424.0
Fiscal year before current fiscal year	1,493.0		1,692.0
Two years before current fiscal year	1,604.0		1,521.0
Three years before current fiscal year	1,422.0		802.0
Four years before current fiscal year	729.0		346.0
Prior	1,073.0		854.0
Revolving Loans Amortized Cost Basis	0.0		1.0
Total Loans and Leases	7,986.0		6,640.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.1		0.0
Fiscal year before current fiscal year, charge-off	0.6		0.0
Two years before current fiscal year, charge-off	0.3		0.0
Three years before current fiscal year, charge-off	0.2		0.0
Four years before current fiscal year, charge-off	0.0		0.0
Prior, charge-off	1.4		0.7
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	2.6		0.7		0.6
Total consumer loans | Residential mortgages | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,663.0		1,421.0
Fiscal year before current fiscal year	1,478.0		1,686.0
Two years before current fiscal year	1,598.0		1,516.0
Three years before current fiscal year	1,417.0		799.0
Four years before current fiscal year	728.0		343.0
Prior	1,048.0		819.0
Revolving Loans Amortized Cost Basis	0.0		1.0
Total Loans and Leases	7,932.0		6,585.0
Total consumer loans | Residential mortgages | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	2.0		3.0
Fiscal year before current fiscal year	15.0		6.0
Two years before current fiscal year	6.0		5.0
Three years before current fiscal year	5.0		3.0
Four years before current fiscal year	1.0		3.0
Prior	25.0		35.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	54.0		55.0
Total consumer loans | Indirect installment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	397.0		313.0
Fiscal year before current fiscal year	27.0		395.0
Two years before current fiscal year	73.0		246.0
Three years before current fiscal year	148.0		102.0
Four years before current fiscal year	51.0		43.0
Prior	43.0		50.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	739.0		1,149.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.2		0.4
Fiscal year before current fiscal year, charge-off	1.8		4.3
Two years before current fiscal year, charge-off	4.5		3.7
Three years before current fiscal year, charge-off	3.2		0.6
Four years before current fiscal year, charge-off	0.5		0.3
Prior, charge-off	1.6		1.4
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	11.8		10.7		6.1
Total consumer loans | Indirect installment | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	396.0		311.0
Fiscal year before current fiscal year	24.0		387.0
Two years before current fiscal year	67.0		238.0
Three years before current fiscal year	142.0		100.0
Four years before current fiscal year	49.0		42.0
Prior	42.0		49.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	720.0		1,127.0
Total consumer loans | Indirect installment | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1.0		2.0
Fiscal year before current fiscal year	3.0		8.0
Two years before current fiscal year	6.0		8.0
Three years before current fiscal year	6.0		2.0
Four years before current fiscal year	2.0		1.0
Prior	1.0		1.0
Revolving Loans Amortized Cost Basis	0.0		0.0
Total Loans and Leases	19.0		22.0
Total consumer loans | Consumer lines of credit
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	8.0		38.0
Fiscal year before current fiscal year	29.0		62.0
Two years before current fiscal year	52.0		15.0
Three years before current fiscal year	14.0		2.0
Four years before current fiscal year	1.0		3.0
Prior	127.0		130.0
Revolving Loans Amortized Cost Basis	1,143.0		1,047.0
Total Loans and Leases	1,374.0		1,297.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, charge-off	0.0		0.1
Fiscal year before current fiscal year, charge-off	0.1		0.0
Two years before current fiscal year, charge-off	0.1		0.0
Three years before current fiscal year, charge-off	0.1		0.0
Four years before current fiscal year, charge-off	0.0		0.0
Prior, charge-off	1.3		0.9
Revolving Loans Amortized Cost Basis, charge-off	0.0		0.0
Total Loans and Leases, charge-off	1.6		1.0		$ 1.0
Total consumer loans | Consumer lines of credit | Current
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	8.0		38.0
Fiscal year before current fiscal year	29.0		61.0
Two years before current fiscal year	51.0		14.0
Three years before current fiscal year	13.0		2.0
Four years before current fiscal year	1.0		3.0
Prior	117.0		117.0
Revolving Loans Amortized Cost Basis	1,141.0		1,044.0
Total Loans and Leases	1,360.0		1,279.0
Total consumer loans | Consumer lines of credit | Past due
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0.0		0.0
Fiscal year before current fiscal year	0.0		1.0
Two years before current fiscal year	1.0		1.0
Three years before current fiscal year	1.0		0.0
Four years before current fiscal year	0.0		0.0
Prior	10.0		13.0
Revolving Loans Amortized Cost Basis	2.0		3.0
Total Loans and Leases	$ 14.0		$ 18.0

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