FAIR VALUE MEASUREMENTS - Schedule of Fair Values of Corporation's Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities available for sale	$ 3,254	$ 3,275
Debt securities held to maturity	3,593	3,687
Net loans and leases, including loans held for sale	45	12
Derivative assets	116	96
Long-term borrowings	616
Derivative liabilities	328	411
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,576	1,674
Debt securities available for sale	3,254	3,275
Debt securities held to maturity	3,911	4,087
Net loans and leases, including loans held for sale	32,405	29,977
Loan servicing rights	61	55
Derivative assets	116	96
Accrued interest receivable	160	126
Deposits	34,711	34,770
Short-term borrowings	2,506	1,372
Long-term borrowings	1,971	1,093
Derivative liabilities	328	411
Accrued interest payable	69	31
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,576	1,674
Debt securities available for sale	3,254	3,275
Debt securities held to maturity	3,593	3,687
Net loans and leases, including loans held for sale	30,641	29,008
Loan servicing rights	73	71
Derivative assets	116	96
Accrued interest receivable	160	126
Deposits	34,654	34,673
Short-term borrowings	2,505	1,369
Long-term borrowings	1,928	1,061
Derivative liabilities	328	411
Accrued interest payable	69	31
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,576	1,674
Debt securities available for sale	420	257
Debt securities held to maturity	0	0
Net loans and leases, including loans held for sale	0	0
Loan servicing rights	0	0
Derivative assets	0	0
Accrued interest receivable	160	126
Deposits	28,496	31,158
Short-term borrowings	2,505	1,369
Long-term borrowings	0	0
Derivative liabilities	0	0
Accrued interest payable	69	31
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Debt securities available for sale	2,834	3,018
Debt securities held to maturity	3,593	3,687
Net loans and leases, including loans held for sale	150	91
Loan servicing rights	0	0
Derivative assets	111	96
Accrued interest receivable	0	0
Deposits	6,158	3,515
Short-term borrowings	0	0
Long-term borrowings	1,192	0
Derivative liabilities	328	399
Accrued interest payable	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Debt securities available for sale	0	0
Debt securities held to maturity	0	0
Net loans and leases, including loans held for sale	30,491	28,917
Loan servicing rights	73	71
Derivative assets	5	0
Accrued interest receivable	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	736	1,061
Derivative liabilities	0	12
Accrued interest payable	$ 0	$ 0