LOANS AND LEASES - Loans Held For Sale (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	$ 3,631	$ 1,946
Other loans held for sale	1,362	1,384
Residential loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	3,449	1,778
Other loans held for sale	0	1,101
Commercial loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	182	168
Other loans held for sale	426	$ 283
Education loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	0
Other loans held for sale	$ 936