Earnings per Share - Reconciliation of Average Shares Outstanding for Basic and Diluted Earnings Per Share (Detail) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Weighted average shares outstanding	17,197	17,614	18,303
Less: Unallocated ESOP shares	(412)	(446)	(480)
Unallocated Incentive award shares and shares held by deferred compensation plan	(98)	(97)	(93)
Average basic shares outstanding	16,687	17,071	17,730
Average basic shares outstanding	16,687	17,071	17,730
Add: Effect of dilutive securities:
Incentive awards and shares held by deferred compensation plan	110	86	99
Average diluted shares outstanding	16,797	17,157	17,829

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Unallocated Incentive Award Shares And Shares Held By Deferred Compensation Plan

+ References

No definition available.

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- Definition

Number of shares issued pursuant to the terms of a deferred compensation arrangement.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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- Definition

Number of employee stock ownership plan (ESOP) shares that have not been committed to be released determined by relating the portion of time within a reporting period that these shares have been outstanding to the total time in that period.

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- Definition

This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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-Glossary Weighted-Average Number of Common Shares Outstanding

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