Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Component of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance	$ (1,304)	$ (859)	$ 991
Unrealized holding gains (losses), net of tax	1,456	(2,899)	(111)
Reclassification adjustment, net of tax	(460)		(1,285)
Pension liability adjustment, net of tax	(1,246)	2,454	(454)
Change during period	(250)	(445)	(1,850)
Accumulated other comprehensive loss, Ending Balance	(1,554)	(1,304)	(859)
Securities Available for Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance	(1,129)	1,770	3,166
Unrealized holding gains (losses), net of tax	1,456	(2,899)	(111)
Reclassification adjustment, net of tax	(460)		(1,285)
Change during period	996	(2,899)	(1,396)
Accumulated other comprehensive loss, Ending Balance	(133)	(1,129)	1,770
Adjustments Related to Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance	(175)	(2,629)	(2,175)
Pension liability adjustment, net of tax	(1,246)	2,454	(454)
Change during period	(1,246)	2,454	(454)
Accumulated other comprehensive loss, Ending Balance	$ (1,421)	$ (175)	$ (2,629)

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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- Definition

Amount after tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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