LOANS AND LEASES - Narrative (Details) - USD ($)		12 Months Ended
	Mar. 27, 2023	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, accrued interest receivable		$ 603,000,000	$ 625,000,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]		Other assets	Other assets
Financing receivable, amortization of purchase discount		$ 505,000,000	$ 733,000,000
Financing receivable, threshold period past due		30 days
Mortgage servicing rights		$ 64,000,000	62,000,000
Modified loans that subsequently defaulted		62,000,000
Financing receivable, troubled debt restructuring, commitment to lend		55,000,000	13,000,000
Other secured financings | Federal Reserve Bank of Richmond | Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Long-term line of credit		0	0
Purchase Money Note
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt instrument, term	5 years
Notes payable	$ 36,070,000,000.00
FDIC Credit Facility
Accounts, Notes, Loans and Financing Receivable [Line Items]
FDIC advances, maximum amount available	$ 70,000,000,000
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, amortization of purchase discount		$ 81,000,000	$ 128,000,000