Earnings Per Share - Computation of Earnings Per Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 8,336us-gaap_NetIncomeLoss	$ 5,650us-gaap_NetIncomeLoss	$ 8,234us-gaap_NetIncomeLoss	$ 4,859us-gaap_NetIncomeLoss	$ 7,365us-gaap_NetIncomeLoss
Average number of common shares outstanding	22,727				16,097
Effect of dilutive stock options and restricted stock	223				225
Average number of common shares outstanding used to calculate diluted earnings per share	22,950				16,322
Options excluded from diluted earnings per share because the effect of these options was antidilutive	23				101

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-Glossary Diluted Earnings Per Share

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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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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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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