Net Income Per Common Share	6 Months Ended
Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income Per Common Share	Net Income Per Common Share For the purpose of computing diluted net income per common share, the weighted-average number of common shares outstanding is increased for the potential dilutive effects of stock-based incentive plans. For the purpose of computing diluted net income per common share, the weighted-average number of common shares outstanding was increased by 553,938 and 544,960 for the three month periods ended June 30, 2018 and 2017, respectively, and by 552,467 and 507,987 for the six month periods ended June 30, 2018 and 2017, respectively, to account for the potential dilutive effect of stock-based incentive plans. There were no adjustments to net income for the purposes of computing income available to common stockholders for the periods. The calculation of weighted-average diluted shares outstanding excludes all shares that would have been anti-dilutive. During the three month periods ended June 30, 2018 and 2017, the Company excluded 139,307 and 0 stock awards, respectively, from the calculation of weighted-average diluted shares outstanding as the stock awards were considered anti-dilutive. During the six month periods ended June 30, 2018 and 2017, the Company excluded 146,607 and 88,891 stock awards, respectively, from the calculation of weighted-average diluted shares outstanding as the stock awards were considered anti-dilutive. The Company granted 102,400 stock options, 88,543 restricted stock unit awards and 70,005 performance share awards ("PSAs") in February 2018 as part of its annual grant awards. All of the stock options and the restricted stock unit awards vest upon meeting certain service conditions. The restricted stock unit awards are included in basic weighted-average common shares outstanding as they contain nonforfeitable rights to dividend payments. The PSAs are part of the long-term Performance Share Award Program (the "Awards Program") and are based on performance goals that are driven by a combination of independently measured metrics (depending on the grant year) with each metric being weighted equally. The metrics for awards granted in 2018 include the Company’s total shareholder return (“TSR”), return on invested capital (“ROIC”) and operating income before depreciation and amortization growth ("EBITDA growth"). The TSR and EBITDA growth metrics are designed to assess the long-term Company performance relative to the performance of companies included in the Russell 2000 Index over a three-year performance period. ROIC is designed to assess the Company's performance compared to pre-established Company targets over a three-year performance period. The participants can earn from zero to 250% of the target award and the award includes a forfeitable right to dividend equivalents, which are not included in the aggregate target award numbers. The fair value of the TSR portion of the PSA was determined using a Monte Carlo valuation method as the award contains a market condition.

Net Income Per Common Share

For the purpose of computing diluted net income per common share, the weighted-average number of common shares outstanding is increased for the potential dilutive effects of stock-based incentive plans. For the purpose of computing diluted net income per common share, the weighted-average number of common shares outstanding was increased by 553,938 and 544,960 for the three month periods ended June 30, 2018 and 2017, respectively, and by 552,467 and 507,987 for the six month periods ended June 30, 2018 and 2017, respectively, to account for the potential dilutive effect of stock-based incentive plans. There were no adjustments to net income for the purposes of computing income available to common stockholders for the periods.

The calculation of weighted-average diluted shares outstanding excludes all shares that would have been anti-dilutive. During the three month periods ended June 30, 2018 and 2017, the Company excluded 139,307 and 0 stock awards, respectively, from the calculation of weighted-average diluted shares outstanding as the stock awards were considered anti-dilutive. During the six month periods ended June 30, 2018 and 2017, the Company excluded 146,607 and 88,891 stock awards, respectively, from the calculation of weighted-average diluted shares outstanding as the stock awards were considered anti-dilutive.

The Company granted 102,400 stock options, 88,543 restricted stock unit awards and 70,005 performance share awards ("PSAs") in February 2018 as part of its annual grant awards. All of the stock options and the restricted stock unit awards vest upon meeting certain service conditions. The restricted stock unit awards are included in basic weighted-average common shares outstanding as they contain nonforfeitable rights to dividend payments. The PSAs are part of the long-term Performance Share Award Program (the "Awards Program") and are based on performance goals that are driven by a combination of independently measured metrics (depending on the grant year) with each metric being weighted equally. The metrics for awards granted in 2018 include the Company’s total shareholder return (“TSR”), return on invested capital (“ROIC”) and operating income before depreciation and amortization growth ("EBITDA growth"). The TSR and EBITDA growth metrics are designed to assess the long-term Company performance relative to the performance of companies included in the Russell 2000 Index over a three-year performance period. ROIC is designed to assess the Company's performance compared to pre-established Company targets over a three-year performance period. The participants can earn from zero to 250% of the target award and the award includes a forfeitable right to dividend equivalents, which are not included in the aggregate target award numbers. The fair value of the TSR portion of the PSA was determined using a Monte Carlo valuation method as the award contains a market condition.