Loans and Leases - Schedule of Allowance for Loan Losses (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 19,187,000,000	$ 18,799,000,000
Total Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	19,160,000,000	18,771,000,000
Amount of loan losses related to institutional loans individually evaluated for impairment	1,000,000	0
Amount of loan losses related to institutional loans collectively evaluated for impairment	46,000,000	46,000,000
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27,000,000	28,000,000
Individually Evaluated for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15,000,000	0
Individually Evaluated for Impairment | Total Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15,000,000	0
Individually Evaluated for Impairment | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Collectively Evaluated for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	19,172,000,000	18,799,000,000
Collectively Evaluated for Impairment | Total Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	19,145,000,000	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