Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ 0	$ 0
Interest Rate Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	572	277
Commitments to sell mortgage loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(941)	(313)
Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	276	224
Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Commitments [Member] | Net gains on loan sales and commissions on loans originated for others [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	572	277
Derivatives not Designated as Hedging Instruments [Member] | Commitments to sell mortgage loans [Member] | Net gains on loan sales and commissions on loans originated for others [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(941)	(313)
Derivatives not Designated as Hedging Instruments [Member] | Interest rate swaps with customers [Member] | Net gains (losses) on interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	3,633	1,030
Derivatives not Designated as Hedging Instruments [Member] | Mirror swaps with counterparties [Member] | Net gains (losses) on interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(2,836)	(770)
Derivatives not Designated as Hedging Instruments [Member] | Risk participation agreement [Member] | Net gains (losses) on interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ (152)	$ 0