LOANS AND LEASES - Loans Held For Sale (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	$ 505	$ 676
Other loans held for sale	50	103
Residential loans held for sale | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	437	614
Other loans held for sale	0	0
Commercial loans held for sale | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	68	62
Other loans held for sale	$ 50	$ 103