Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive (loss) income, Before Tax	$ 6,556	$ (2,812)
Total other comprehensive (loss) income, Tax Effect	(2,678)	1,149
Total other comprehensive income (loss)	3,878	(1,663)
Unrealized Gains on Securities Available for Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (losses) gains, Before Tax	6,287	(2,739)
Reclassification adjustment, Before Tax	350	(511)
Total other comprehensive (loss) income, Before Tax	6,637	(3,250)
Net (losses) gains, Tax Effect	(2,568)	1,119
Reclassification adjustment, Tax Effect	143	(209)
Total other comprehensive (loss) income, Tax Effect	(2,711)	1,328
Net (losses) gains, After Tax	3,719	(1,620)
Reclassification adjustment, After Tax	207	(302)
Total other comprehensive income (loss)	3,926	(1,922)
Post-Retirement Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive (loss) income, Before Tax	(81)	438
Total other comprehensive (loss) income, Tax Effect	33	(179)
Total other comprehensive income (loss)	$ (48)	$ 259