LOANS AND LEASES - Schedule of Loans Charge-offs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 159	$ 176	$ 287	$ 238
Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			4	19
Year two			49	56
Year three			88	34
Year four			32	51
Year five			7	22
Prior year			60	25
Revolving			46	31
Revolving Converted to Term Loans			1	0
Total			287	238
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	96	70	171	124
Commercial | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			4	3
Year two			23	36
Year three			49	19
Year four			12	6
Year five			4	21
Prior year			54	23
Revolving			24	16
Revolving Converted to Term Loans			1	0
Total			171	124
Commercial | Non-owner occupied commercial mortgage | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	0
Year two			0	0
Year three			0	0
Year four			0	0
Year five			0	17
Prior year			46	12
Revolving			0	0
Revolving Converted to Term Loans			0	0
Total			46	29
Commercial | Commercial and industrial | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			4	3
Year two			17	31
Year three			39	16
Year four			7	5
Year five			2	3
Prior year			6	10
Revolving			24	16
Revolving Converted to Term Loans			1	0
Total			100	84
Commercial | Leases | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	0
Year two			6	5
Year three			10	3
Year four			5	1
Year five			2	1
Prior year			2	1
Revolving			0	0
Revolving Converted to Term Loans			0	0
Total			25	11
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	6	6	13	14
Consumer | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	3
Year two			2	2
Year three			2	1
Year four			1	0
Year five			0	0
Prior year			0	2
Revolving			8	6
Revolving Converted to Term Loans			0	0
Total			13	14
Consumer | Residential mortgage | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one				0
Year two				0
Year three				0
Year four				0
Year five				0
Prior year				2
Revolving				0
Revolving Converted to Term Loans				0
Total				2
Consumer | Consumer auto | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	0
Year two			1	1
Year three			1	0
Year four			1	0
Year five			0	0
Prior year			0	0
Revolving			0	0
Revolving Converted to Term Loans			0	0
Total			3	1
Consumer | Consumer other | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	3
Year two			1	1
Year three			1	1
Year four			0	0
Year five			0	0
Prior year			0	0
Revolving			8	6
Revolving Converted to Term Loans			0	0
Total			10	11
SVB
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 57	$ 100	103	100
SVB | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	13
Year two			24	18
Year three			37	14
Year four			19	45
Year five			3	1
Prior year			6	0
Revolving			14	9
Revolving Converted to Term Loans			0	0
Total			103	100
SVB | Investor dependent - early stage | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	12
Year two			23	13
Year three			30	4
Year four			12	0
Year five			2	0
Prior year			4	0
Revolving			4	0
Revolving Converted to Term Loans			0	0
Total			75	29
SVB | Investor dependent - growth stage | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	1
Year two			0	5
Year three			7	10
Year four			7	3
Year five			1	1
Prior year			0	0
Revolving			1	4
Revolving Converted to Term Loans			0	0
Total			16	24
SVB | Innovation C&I and cash flow dependent | Amount of Principal Forgiven
Accounts, Notes, Loans and Financing Receivable [Line Items]
Year one			0	0
Year two			1	0
Year three			0	0
Year four			0	42
Year five			0	0
Prior year			2	0
Revolving			9	5
Revolving Converted to Term Loans			0	0
Total			$ 12	$ 47