Financial Derivatives - Schedule of Derivative Instruments, Impact on Results of Operations (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(losses) on financial derivatives and hedging activities	$ 808,000	$ 3,024,000	$ (12,468,000)	$ 22,501,000
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(2,549,000)	2,996,000	4,019,000	(14,871,000)
Gain (Loss) on Fair Value Hedges Recognized in Earnings	3,061,000	3,000,000	9,029,000	8,458,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(losses) on financial derivatives and hedging activities	(2,253,000)	24,000	(21,497,000)	14,043,000
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	5,610,000	4,000	5,010,000	23,329,000
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	200,000	(100,000)	300,000	500,000
Gain (Loss) on Components Excluded from Assessment of Interest Rate Fair Value Hedge Effectiveness	(2,900,000)	(3,100,000)	(8,700,000)	(8,000,000)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(losses) on financial derivatives and hedging activities	(2,074,000)	1,192,000	(19,748,000)	14,950,000
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(losses) on financial derivatives and hedging activities	(210,000)	(861,000)	(1,297,000)	(768,000)
Future [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(losses) on financial derivatives and hedging activities	$ 31,000	$ (307,000)	$ (452,000)	$ (139,000)