Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic and Diluted Earnings per Share [Line Items]
Net income	$ 2,958	$ 3,114	$ 22,894	$ 25,541
Weighted-average common shares outstanding (in shares)	25,133,035	25,366,283	25,288,068	25,288,086
Weighted-average common shares for EPS calculation (in shares)	25,624,686	25,795,476	25,752,525	25,629,577
Basic earnings per common share (in dollars per share)	$ 0.12	$ 0.12	$ 0.91	$ 1.01
Diluted earnings per common share (in dollars per share)	$ 0.12	$ 0.12	$ 0.89	$ 1.00
Awards excluded from diluted earnings per share calculation (in shares)	0	0	0	0
Restricted Stock Unit Awards
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)	248,717	155,270	248,717	155,270
Stock Options
Basic and Diluted Earnings per Share [Line Items]
Add dilutive effect of share-based awards outstanding (in shares)	242,934	273,923	215,740	186,221

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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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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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 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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