Financial Derivatives Schedule of Derivative Instruments, Gain(Loss) in Statement of Financial Performance (Details) (USD $)	3 Months Ended				12 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Designated as Hedging Instrument [Member] Interest Rate Swap, Pay Fixed Non-Callable [Member]	Mar. 31, 2013 Not Designated as Hedging Instrument [Member] Interest Rate Swap, Pay Fixed Non-Callable [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Interest Rate Swap, Pay Fixed Non-Callable [Member]	Mar. 31, 2013 Non-Interest Income [Member]	Mar. 31, 2012 Non-Interest Income [Member]	Mar. 31, 2013 Non-Interest Income [Member] Designated as Hedging Instrument [Member]		Mar. 31, 2012 Non-Interest Income [Member] Designated as Hedging Instrument [Member]		Mar. 31, 2013 Non-Interest Income [Member] Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Mar. 31, 2012 Non-Interest Income [Member] Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Mar. 31, 2013 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2013 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Mar. 31, 2012 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Mar. 31, 2013 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Credit Default Swap [Member]	Mar. 31, 2012 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Credit Default Swap [Member]	Mar. 31, 2013 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Agency Forward [Member]	Mar. 31, 2012 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Agency Forward [Member]	Mar. 31, 2013 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Treasury Futures [Member]	Mar. 31, 2012 Non-Interest Income [Member] Not Designated as Hedging Instrument [Member] Treasury Futures [Member]
Derivative [Line Items]
Derivative, Weighted-Average Receive Rate			0.30%	0.29%	0.32%
Gain (Loss) on Components Excluded from Assessment of Interest Rate Fair Value Hedge Effectiveness												$ 3,000,000
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments												5,791,000	0
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge								(3,138,000)		0
Gain (Loss) on Fair Value Hedges Recognized in Earnings								2,653,000	[1]	0	[1]
Gain (Loss) on Derivative Instruments, Net, Pretax														1,841,000	6,400,000	2,846,000	6,306,000	0	(75,000)	(984,000)	203,000	(21,000)	(34,000)
Gain (loss) on derivatives instruments and hedging activity net pretax	4,494,000	6,400,000				4,494,000	6,400,000
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net												$ (300,000)
Derivative, Average Remaining Maturity			3 years 9 months 29 days	4 years 2 months 5 days	4 years 1 month 20 days

[1] Includes gains of $3.0 million that are excluded from the assessment of hedge effectiveness and losses of $0.3 million due to hedge ineffectiveness for the three months ended March 31, 2013.