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Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Schedule of Quarterly Financial Information Disclosure [Line Items] |  |  |  |  |  |  |  |  |  |  |
Sales | $ 205,522 | $ 216,766 | $ 211,489 | $ 210,971 | $ 224,431 | $ 231,614 | $ 215,734 | $ 207,798 |  |  |
Gross profit | 47,933 | 54,711 | 52,178 | 50,277 | 48,737 | 57,509 | 50,665 | 45,537 | $ 205,099 | $ 202,448 | $ 189,228
Net income | $ 7,588 | $ 13,236 | $ 10,562 | $ 8,659 | $ 11,384 | $ 14,756 | $ 9,710 | $ 7,359 | $ 40,045 | $ 43,209 | $ 41,151
Per common share - diluted |  |  |  |  |  |  |  |  |  |  |
Diluted (in dollars per share) | $ 0.65 | $ 1.14 | $ 0.92 | $ 0.75 | $ 0.99 | $ 1.28 | $ 0.84 | $ 0.64 | $ 3.46 | $ 3.76 | $ 3.42
Average shares |  |  |  |  |  |  |  |  |  |  |
Diluted (in shares) | 11,608 | 11,595 | 11,550 | 11,507 | 11,500 | 11,496 | 11,498 | 11,436 | 11,565 | 11,482 | 12,039
Dividends per share (in dollars per share) | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.08 | $ 0.08 | $ 0.08 | $ 0.08 |  |  |
High |  |  |  |  |  |  |  |  |  |  |
Market price of common stock |  |  |  |  |  |  |  |  |  |  |
Share Price (in dollars per share) | 78.91 | 68.04 | 66.01 | 61.82 | 57.51 | 55.12 | 64.45 | 63.39 | $ 78.91 | $ 57.51 |
Low |  |  |  |  |  |  |  |  |  |  |
Market price of common stock |  |  |  |  |  |  |  |  |  |  |
Share Price (in dollars per share) | $ 59.55 | $ 61.49 | $ 52.82 | $ 48.26 | $ 43.98 | $ 44.48 | $ 48.1 | $ 44.74 | $ 59.55 | $ 43.98 |

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