Investment Securities (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) securities	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Available-for-sale: [Abstract]
Amortized Cost	$ 491,504		$ 491,504		$ 516,829
Gross Unrealized Gains	10,701		10,701		5,052
Gross Unrealized (Losses)	(1,628)		(1,628)		(3,033)
Fair Value	500,577		500,577		518,848
Gain (Loss) on Sale of Securities, Net	404	$ 1	664	$ 230
Held-to-maturity: [Abstract]
Held-to-maturity Securities	112,161		112,161		85,208
Held-to-maturity Securities, Fair Value	113,112		113,112		85,737
Realized Investment Gains (Losses) [Abstract]
Gross gains	404	1	664	230
Gross losses	0	$ 0	0	$ 0
U.S. Treasury securities and obligations of U.S. government corporations & agencies
Available-for-sale: [Abstract]
Amortized Cost	50,065		50,065		90,368
Gross Unrealized Gains	163		163		41
Gross Unrealized (Losses)	(18)		(18)		(268)
Fair Value	50,210		50,210		90,141
Held-to-maturity: [Abstract]
Held-to-maturity Securities	112,161		112,161		85,208
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	1,012		1,012		743
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(61)		(61)		(214)
Held-to-maturity Securities, Fair Value	113,112		113,112		85,737
Obligations of states and political subdivisions
Available-for-sale: [Abstract]
Amortized Cost	107,874		107,874		107,164
Gross Unrealized Gains	5,167		5,167		3,608
Gross Unrealized (Losses)	0		0		(55)
Fair Value	113,041		113,041		110,717
Mortgage-backed securities: GSE residential
Available-for-sale: [Abstract]
Amortized Cost	326,436		326,436		312,132
Gross Unrealized Gains	5,309		5,309		1,374
Gross Unrealized (Losses)	(241)		(241)		(1,452)
Fair Value	331,504		331,504		312,054
Trust preferred securities
Available-for-sale: [Abstract]
Amortized Cost	3,094		3,094		3,130
Gross Unrealized Gains	0		0		0
Gross Unrealized (Losses)	(1,348)		(1,348)		(1,224)
Fair Value	1,746		$ 1,746		1,906
Number of trust preferred securities \| securities			1
Trust preferred securities \| Maximum [Member]
Available-for-sale: [Abstract]
Maturities of Debt Securities			twenty-one years
Other securities
Available-for-sale: [Abstract]
Amortized Cost	4,035		$ 4,035		4,035
Gross Unrealized Gains	62		62		29
Gross Unrealized (Losses)	(21)		(21)		(34)
Fair Value	$ 4,076		$ 4,076		$ 4,030

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of investments in debt securities classified as available-for-sale, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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