Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ 0	$ 0	$ (78)
Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	(707)	(1,145)	245
Commitments to originate fixed rate mortgage loans to be sold [Member] | Net gains on loan sales & commissions on loans originated for others [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	649	1,968	54
Commitments to sell fixed rate mortgage loans [Member] | Net gains on loan sales & commissions on loans originated for others [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	(1,611)	(3,119)	228
Interest rate swaps with customers [Member] | Net (losses) gains on interest rate swaps [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	1,147	2,658	3,785
Mirror swaps with counterparties [Member] | Net (losses) gains on interest rate swaps [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ (892)	$ (2,652)	$ (3,822)