MORTGAGE BANKING AND OTHER - Other Serviced Loans (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other serviced loans	$ 621	$ 761
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other serviced loans	604	80
Commercial and industrial | Loans Insured or Guaranteed by US Government Authorities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other serviced loans	92
Commercial and industrial | Investors Acquisition
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other serviced loans	512
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other serviced loans	$ 354	$ 0