Fair Value Of Assets And Liabilities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 number	Sep. 30, 2012	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain/(loss) on instrument specific credit risk	$ (1,400,000)	$ (900,000)	$ 400,000	$ (400,000)
Number of levels assets and liabilities are grouped in			3
Trading securities	1,343,134,000	1,204,366,000	1,343,134,000	1,204,366,000	1,262,720,000
Capital Markets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	1,327,420,000	1,185,165,000	1,327,420,000	1,185,165,000
Capital Markets [Member] | Trading Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 145,505,000		$ 145,505,000