LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	[1],[2]	$ 110,617	$ 107,669
Loans held for sale		718	625
Mortgage loans serviced for others | Banking Subsidiaries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		20,300	17,300
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		52,031	51,651
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		37,562	37,274
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		11,308	10,624
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		3,161	3,753
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		58,586	56,018
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		17,045	15,115
Retail | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,392	1,858
Retail | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		13,483	14,100
Retail | Home equity loans serviced by others
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		542	750
Retail | Home equity lines of credit serviced by others
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		149	219
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		13,204	13,938
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	[3]	8,134	6,610
Retail | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,848	1,691
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		$ 2,789	$ 1,737

[1] Excluded from the table above are loans held for sale totaling $718 million and $625 million as of December 31, 2017 and 2016, respectively.

[2] Mortgage loans serviced for others by the Company’s subsidiaries are not included above, and amounted to $20.3 billion and $17.3 billion at December 31, 2017 and 2016, respectively.

[3] During first quarter 2017, student loans were renamed “education” loans. Refer to Note 1 “Significant Accountant Policies” for more information.