Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 21,502	$ 18,799
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	16,739	12,814
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,815	4,949
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	74	93
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	847	915
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27	28
Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	17,198	15,204
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15,828	12,415
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	422	1,780
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	74	93
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	847	888
Investment grade | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27	28
Speculative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,286	3,564
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	908	399
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,378	3,138
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	0	27
Speculative | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3	31
Special Mention | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3	0
Special Mention | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	31
Special Mention | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Special Mention | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Special Mention | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	$ 0
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15
Substandard | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Substandard | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15
Substandard | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Substandard | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Substandard | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0