Loans and Leases (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Mar. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Allowance for Loan and Lease Losses, Write-offs	$ 0	$ 0	$ 0	$ 0
Loans and leases, allowance for losses	32,000,000		32,000,000		28,000,000
Aggregate short-duration advances	5,410,000,000		5,410,000,000		2,450,000,000
Loans modified in troubled debt restructurings			0		0
Provisions	2,000,000	0	4,000,000	0
Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Provisions	12,000,000
Institutional
Financing Receivable, Recorded Investment [Line Items]
Allowance for Loan and Lease Losses, Write-offs	0	0	0	0
Amount of loan losses related to institutional loans collectively evaluated for impairment	32,000,000		32,000,000		28,000,000
Provisions	2,000,000	0	4,000,000	0
Institutional | Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Commercial and financial	1,320,000,000		1,320,000,000		724,000,000
Commercial and Financial
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	12,000,000		12,000,000
Adjustment to Provision for Loans and Lease Losses	10,000,000
Commercial and Financial | Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	20,000,000		20,000,000
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Allowance for Loan and Lease Losses, Write-offs	0	0	0	0
Amount of loan losses related to institutional loans collectively evaluated for impairment					28,000,000
Loan modification, recorded investment					130,000,000	130,000,000
Impairment loss recognized					0
Provisions	$ 0	$ 0	$ 0	$ 0