Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
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	(486)	(787)	1,636	(869)
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	127	1,810	(1,646)	3,009
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	(667)	(2,660)	3,057	(3,965)
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	306	340	(105)	949
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	$ (252)	$ (277)	$ 330	$ (862)