Loans and Leases - Schedule of Allowance for Loan Losses (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
Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	18,771	18,171
Amount of loan losses related to institutional loans collectively evaluated for impairment	46	38
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	28	28
Collectively Evaluated for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	18,799	18,199
Collectively Evaluated for Impairment | Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	18,771	18,171
Collectively Evaluated for Impairment | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 28	$ 28