Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ 0	$ 0	$ 0	$ 0
Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(341)	(46)	(82)	(432)
Commitments to originate fixed rate mortgage loans to be sold [Member] | Net gains on loan sales and commissions on loans originated for others [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	1,248	(53)	1,199	33
Commitments to sell fixed rate mortgage loans [Member] | Net gains on loan sales and commissions on loans originated for others [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(1,586)	42	(1,305)	(506)
Interest rate swaps with customers [Member] | Net gains (losses) on interest rate swaps [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	398	1,214	609	1,118
Mirror swaps with counterparties [Member] | Net gains (losses) on interest rate swaps [Member] | Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ (401)	$ (1,249)	$ (585)	$ (1,077)