Derivative Financial Instruments (Derivatives not Designated as Hedging Instruments, Effect in Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ 0	$ 0	$ 0	$ 0
Interest Rate Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	864	498	1,002	1,101
Commitments to sell mortgage loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(1,470)	(672)	(999)	(1,737)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	(279)	165	1,692	(74)
Not Designated as Hedging Instrument [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	864	498	1,002	1,101
Not Designated as Hedging Instrument [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	(1,470)	(672)	(999)	(1,737)
Not Designated as Hedging Instrument [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	6,448	317	8,717	2,467
Not Designated as Hedging Instrument [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	(6,081)	22	(6,799)	(1,905)
Not Designated as Hedging Instrument [Member] | Risk participation-out agreement [Member] | Net gains (losses) on interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income	$ (40)	$ 0	$ (229)	$ 0