Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 19,067	$ 18,199
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	14,019	13,721
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	3,981	3,317
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	99	130
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	917	1,003
Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	23	0
Other
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	15,701	15,421
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	13,683	13,304
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	1,001	1,011
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	99	130
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	890	976
Investment grade | Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	0	0
Investment grade | Other
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	3,341	2,778
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	336	417
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	2,955	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 | Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	23	0
Speculative | Other
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	25
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	25
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 | Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	0
Special Mention | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$ 0