Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 19,839	$ 18,799
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,433	12,814
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,421	4,949
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	79	93
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	879	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	16,148	15,204
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,116	12,415
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,075	1,780
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	79	93
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	851	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	3,674	3,564
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	315	399
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,331	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	2	31
Special Mention | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2	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
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15
Doubtful | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Doubtful | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15
Doubtful | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Doubtful | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0
Doubtful | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0