Accumulated Other Comprehensive Loss - Schedule of Changes in Component of Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance	$ (1,554)	$ (1,304)
Unrealized holding gains net of tax	570	450
Reclassification adjustment, net of tax	34
Change during period	604	450
Accumulated other comprehensive loss, Ending Balance	(950)	(854)
Securities Available for Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance	(133)	(1,129)
Unrealized holding gains net of tax	570	450
Reclassification adjustment, net of tax	34
Change during period	604	450
Accumulated other comprehensive loss, Ending Balance	471	(679)
Adjustments Related to Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, Beginning Balance			(1,421)	(175)
Accumulated other comprehensive loss, Ending Balance	$ (1,421)	$ (175)	$ (1,421)	$ (175)

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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 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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- Definition

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

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