Earnings Per Share - Reconciliation of Basic and Diluted Weighted Average Shares Outstanding (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 29, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jul. 01, 2016 |
Apr. 01, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||||||||||
| Net income | $ 41,568 | $ 5,800 | $ 5,461 | $ 6,668 | $ 4,409 | $ 6,607 | $ 6,050 | $ 6,589 | $ 59,497 | $ 23,655 | $ 30,973 |
| Weighted average common shares outstanding - basic (in shares) | 11,026 | 11,075 | 10,987 | 10,909 | 10,794 | 10,733 | 10,702 | 10,628 | 11,021 | 10,714 | 10,551 |
| Add: Dilutive impact of stock options (in shares) | 67 | 97 | 98 | ||||||||
| Diluted weighted average common shares outstanding (in shares) | 11,234 | 11,272 | 11,191 | 11,075 | 10,988 | 11,061 | 10,958 | 10,856 | 11,209 | 10,974 | 10,825 |
| Basic earnings per share (in dollars per share) | $ 3.77 | $ 0.52 | $ 0.50 | $ 0.61 | $ 0.40 | $ 0.62 | $ 0.57 | $ 0.62 | $ 5.40 | $ 2.21 | $ 2.94 |
| Diluted earnings per share (in dollars per share) | $ 3.70 | $ 0.51 | $ 0.49 | $ 0.60 | $ 0.40 | $ 0.60 | $ 0.55 | $ 0.61 | $ 5.31 | $ 2.16 | $ 2.86 |
| Anti-dilutive restricted stock units | |||||||||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||||||||||
| Add: Dilutive impact of restricted stock units (in shares) | 121 | 163 | 176 | ||||||||