LOANS AND LEASES - Loans Held For Sale (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	$ 3,616	$ 3,564
Other loans held for sale	82	439
Residential loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	3,499	3,416
Other loans held for sale	0	0
Commercial loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	117	148
Other loans held for sale	$ 82	$ 439