LOANS AND LEASES - Loans Held For Sale (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	$ 2,911	$ 1,946
Other loans held for sale	350	1,384
Residential loans held for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at fair value	2,708	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	203	168
Other loans held for sale	$ 350	$ 283