Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 18,799	$ 18,199
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	12,814	13,721
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,949	3,317
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	93	130
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	915	1,003
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	28	28
Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15,204	15,421
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	12,415	13,304
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,780	1,011
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	93	130
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	888	976
Investment grade | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	28	0
Speculative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,564	2,778
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	399	417
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,138	2,306
Speculative | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Speculative | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27	27
Speculative | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	$ 28
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	31
Special Mention | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Special Mention | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	31
Special Mention | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Special Mention | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Special Mention | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0