Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 17,574	$ 20,385	$ 12,555
Available-for-sale investment securities:
Gross unrealized holding (loss) gain arising in the period	(25,130)	2,706	15,053
Related tax benefit (expense)	8,795	(947)	(5,269)
Less: reclassification adjustment for net gain included in net income	489	3,548	473
Related tax expense	(171)	(1,242)	(166)
Net effect on other comprehensive (loss) income	(16,653)	(547)	9,477
Defined benefit plans:
Net gain (loss) arising during the period	3,788	(1,320)	(6,448)
Related tax (expense) benefit	(1,326)	462	2,257
Amortization of unrecognized loss and service cost on benefit plans	182	161	76
Related tax expense	(64)	(57)	(27)
Recognition of loss due to settlement and curtailment	270	835	815
Related tax expense	(95)	(292)	(285)
Net effect on other comprehensive income (loss)	2,755	(211)	(3,612)
Total other comprehensive (loss) income, net of tax	(13,898)	(758)	5,865
Total comprehensive income	$ 3,676	$ 19,627	$ 18,420