Loans and Leases - Schedule of Allowance for Loan Losses (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 21,502,000,000	$ 18,799,000,000
Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	21,475,000,000	18,771,000,000
Amount of loan losses related to institutional loans individually evaluated for impairment	0	0
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27,000,000	28,000,000
Collectively Evaluated for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	21,502,000,000	18,799,000,000
Collectively Evaluated for Impairment | Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	21,475,000,000	18,771,000,000
Collectively Evaluated for Impairment | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 27,000,000	$ 28,000,000