Financial Derivatives Schedule of Financial Derivatives - Non Printing Section (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Interest Rate Swap, Pay Fixed Non-Callable [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity	4 years 0 months 25 days
Interest Rate Swap, Pay Fixed Non-Callable [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity	4 years 1 month 20 days	4 years 5 months 23 days
Interest Rate Swap, Receive Fixed Non-Callable [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity	8 months 26 days	11 months 19 days
Interest Rate Swap, Receive Fixed Callable [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity	3 years 10 months 20 days
Basis Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity	1 year 3 months 14 days	1 year 3 months 18 days
Credit Default Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity		8 months 19 days