LOANS AND LEASES - Components of Investments in Leases (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total future minimum lease rentals	$ 2,922
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total future minimum lease rentals	2,922	$ 3,195
Estimated residual value of leased equipment (non-guaranteed)	1,166	1,157
Initial direct costs	20	22
Unearned income on minimum lease rentals and estimated residual value of leased equipment	(355)	(395)
Total leases	$ 3,753	$ 3,979