Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 19,187	$ 18,799
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	13,928	12,814
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,248	4,949
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	86	93
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	898	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	15,450	15,204
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	13,563	12,415
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	904	1,780
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	86	93
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	870	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	3,722	3,564
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	365	399
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,329	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	28	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	0	31
Special Mention | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	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	0
Substandard | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Substandard | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15	0
Substandard | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Substandard | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Substandard | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0	$ 0