Earnings and Dividends per Share - Number of Shares Outstanding for Calculation of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Basic net income and earnings per share, Numerator (Income)	$ 5,763	$ 38
Diluted earnings and earnings per share, Numerator (Income)	$ 5,763	$ 38
Basic net income and earnings per share, Denominator (Shares)	34,592,803	34,215,519
Common stock equivalents arising from stock options, restricted stock awards, and employee stock purchase plan, Denominator (Shares)	48,000	347,000
Diluted earnings and earnings per share, Denominator (Shares)	34,641,390	34,563,139
Basic net income and earnings per share, Per Share Amount	$ 0.17	$ 0.00
Diluted earnings and earnings per share, Per Share Amount	$ 0.17	$ 0.00

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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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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- Definition

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

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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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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