Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Quarterly Financial Data [Abstract] | |||||||||||
| Revenues | $ 214,901 | $ 172,780 | $ 160,473 | $ 143,636 | $ 144,669 | $ 137,396 | $ 131,126 | $ 120,791 | $ 691,790 | $ 533,982 | $ 424,071 |
| Costs and operating expenses | 201,615 | 159,157 | 148,594 | 130,895 | 129,553 | 124,153 | 119,630 | 110,107 | |||
| Operating income | 13,286 | 13,623 | 11,879 | 12,741 | 15,116 | 13,243 | 11,496 | 10,684 | 51,529 | 50,539 | 36,930 |
| Net income | $ 7,184 | $ 7,088 | $ 5,969 | $ 6,552 | $ 7,745 | $ 6,474 | $ 5,479 | $ 5,220 | $ 26,793 | $ 24,918 | $ 19,365 |
| Basic earnings per share: | |||||||||||
| Net income (in dollars per share) | $ 0.67 | $ 0.66 | $ 0.55 | $ 0.61 | $ 0.72 | $ 0.60 | $ 0.51 | $ 0.49 | $ 2.48 | $ 2.32 | $ 1.81 |
| Basic weighted average shares outstanding (in shares) | 10,799,000 | 10,799,000 | 10,799,000 | 10,778,000 | 10,750,000 | 10,750,000 | 10,750,000 | 10,739,000 | 10,793,723 | 10,747,226 | 10,707,824 |
| Diluted earnings per share [Abstract] | |||||||||||
| Net income (in dollars per share) | $ 0.66 | $ 0.65 | $ 0.55 | $ 0.61 | $ 0.72 | $ 0.60 | $ 0.51 | $ 0.49 | $ 2.47 | $ 2.31 | $ 1.81 |
| Diluted weighted average shares outstanding (in shares) | 10,853,000 | 10,826,000 | 10,826,000 | 10,806,000 | 10,814,000 | 10,792,000 | 10,782,000 | 10,760,000 | 10,828,152 | 10,787,270 | 10,742,400 |
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- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References No definition available.
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References No definition available.
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- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes Selling, General and Administrative Expense. No definition available.
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- Definition The net result for the period of deducting operating expenses from operating revenues. No definition available.
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- References No definition available.
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- Definition Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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