LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	[1],[2]	$ 116,660	$ 110,617
Loans held for sale		1,300	718
Mortgage loans serviced for others | Banking Subsidiaries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		69,600	20,300
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		56,783	52,031
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		40,857	37,562
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		13,023	11,308
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		2,903	3,161
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		59,877	58,586
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		18,978	17,045
Retail | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,073	1,392
Retail | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		12,710	13,483
Retail | Home equity loans serviced by others
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		399	542
Retail | Home equity lines of credit serviced by others
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		104	149
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		12,106	13,204
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		8,900	8,134
Retail | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,991	1,848
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		$ 3,616	$ 2,789

[1] Excluded from the table above are loans held for sale totaling $1.3 billion and $718 million as of December 31, 2018 and 2017, respectively.

[2] Mortgage loans serviced for others by the Company’s subsidiaries are not included above, and amounted to $69.6 billion and $20.3 billion at December 31, 2018 and 2017, respectively.