Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comprehensive Income [Abstract]
Net income	$ 19,925	$ 17,507	$ 13,926
Other comprehensive income, net of tax:
Reclassification adjustments for OTTI losses included in income	652	870	342
Reclassification adjustments for OTTI losses included in income, Tax effect	(178)	(265)	(119)
Unrealized gains and losses on securities available-for-sale: Reclassification adjustment on OTTI losses included in income, Net of tax amount	474	605	223
Unrealized (losses) gains on available for sale securities	(8,741)	19,819	8,990
Unrealized (losses) gains on available for sale securities, Tax effect	3,578	(7,444)	(3,486)
Unrealized (losses) gains on available for sale securities: Unrealized holding gains arising during the period, Net of tax amount	(5,163)	12,375	5,504
Reclassification adjustment for realized gains arising during this period	(2,363)	(2,882)	(3,976)
Reclassification adjustment for realized gains arising during this period, Tax effect	645	879	1,380
Unrealized gains and losses on securities available-for-sale: Reclassification adjustment for realized gains arising during the period, Net of tax amount	(1,718)	(2,003)	(2,596)
Unrealized holding gains on securities transferred from available-for-sale to held-to-maturity securities	(2,612)	0	291
Unrealized holding gains on securities transferred from available-for-sale to held-to-maturity securities, Tax effect	1,064	0	(110)
Unrealized gains and losses on securities available-for-sale: Unrealized holding losses / gains on securities transferred from available-for-sale to held-to-maturity securities, Net of tax amount	(1,548)	0	181
Amortization of unrealized holding gains on securities transferred from available-for-sale to held-to-maturity securities	(58)	(2)	(46)
Amortization of unrealized holding gains on securities transferred from available-for-sale to held-to-maturity securities, Tax effect	19	1	28
Unrealized gains and losses on securities available-for-sale: Amortization of unrealized holding gains on securities transferred from available-for-sale to held-to-maturity securities, Net of tax amount	(39)	(1)	(18)
Pension plan:
Actuarial gains (losses)	654	(790)	(1,649)
Actuarial gains (losses), Tax effect	(267)	323	584
Actuarial gains (losses), Net of tax amount	387	(467)	(1,065)
Total other comprehensive (loss) income	(7,607)	10,509	2,229
Total comprehensive income	$ 12,318	$ 28,016	$ 16,155