Financial Derivatives - Schedule of Derivative Instruments, Gain(Loss) in Statement of Financial Performance (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Derivative [Line Items]
Gain (loss) on derivatives instruments and hedging activity net pretax	$ 3,024,000		$ 1,558,000		$ 22,501,000		$ (23,334,000)
Non-Interest Income [Member]
Derivative [Line Items]
Gain (loss) on derivatives instruments and hedging activity net pretax	3,024,000		1,558,000		22,501,000		(23,334,000)
Non-Interest Income [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	2,996,000		8,378,000		(14,871,000)		8,378,000
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3,000,000		3,236,000		8,458,000		3,236,000
Non-Interest Income [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Gain (Loss) on Components Excluded from Assessment of Interest Rate Fair Value Hedge Effectiveness	(3,100,000)		(3,000,000)		(8,000,000)		(3,000,000)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	4,000	[1]	(5,142,000)	[1]	23,329,000	[1]	(5,142,000)	[1]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	(100,000)		200,000		500,000		200,000
Non-Interest Income [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	24,000		(1,678,000)		14,043,000		(26,570,000)
Non-Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	1,192,000		(1,970,000)		14,950,000		(25,853,000)
Non-Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0		(18,000)		0		(93,000)
Non-Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Agency Forward [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(861,000)		452,000		(768,000)		(153,000)
Non-Interest Income [Member] | Not Designated as Hedging Instrument [Member] | Treasury Futures [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (307,000)		$ (142,000)		$ (139,000)		$ (471,000)

[1] he assessment of hedge effectiveness at September 30, 2013, but excluded from the amounts in the table, were losses of $3.1 million and $8.0 million for the three and nine months ended September 30, 2013, respectively, attributable to the fair value of the swaps at the inception of the hedging relationship. Accordingly, the amounts recognized as hedge ineffectiveness for the three and nine months ended September 30, 2013 were losses of $0.1 million and gains of $0.5 million, respectively. The comparable amounts at September 30, 2012 were losses of $3.0 million for the three and nine months ended September 30, 2012 attributable to the fair value of the swaps at the inception of the hedging relationship and, accordingly, gains of $0.2 million for the three and nine months ended September 30, 2012 attributable to hedge ineffectiveness.