Equity (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | $ 205,659 | |
Net earnings | $ 1,523 | $ 1,303 | 4,339 | $ 3,418 |
Foreign currency translation adjustments | (991) | $ 533 | (1,110) | $ 1,220 |
Pension liability adjustment, net of tax | | | (236) | |
Balance, June 30, 2018 | 202,036 | | 202,036 | |
Common Stock [Member] | | | | |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | 10,162 | |
Net earnings | | | 0 | |
Foreign currency translation adjustments | | | 0 | |
Pension liability adjustment, net of tax | | | 0 | |
Cash dividends declared | | | 0 | |
Cash dividends paid to noncontrolling interest | | | 0 | |
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price | | | 197 | |
Issuance of restricted stock | | | 2 | |
Restricted stock forfeited | | | (2) | |
Stock-based compensation expense | | | 0 | |
Shares purchased and retired | | | (199) | |
Balance, June 30, 2018 | 10,160 | | 10,160 | |
Capital in Excess of Par Value [Member] | | | | |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | 55,884 | |
Net earnings | | | 0 | |
Foreign currency translation adjustments | | | 0 | |
Pension liability adjustment, net of tax | | | 0 | |
Cash dividends declared | | | 0 | |
Cash dividends paid to noncontrolling interest | | | 0 | |
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price | | | 3,239 | |
Issuance of restricted stock | | | (2) | |
Restricted stock forfeited | | | 2 | |
Stock-based compensation expense | | | 805 | |
Shares purchased and retired | | | 0 | |
Balance, June 30, 2018 | 59,928 | | 59,928 | |
Reinvested Earnings [Member] | | | | |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | 150,350 | |
Net earnings | | | 4,613 | |
Foreign currency translation adjustments | | | 0 | |
Pension liability adjustment, net of tax | | | 0 | |
Cash dividends declared | | | (4,652) | |
Cash dividends paid to noncontrolling interest | | | 0 | |
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price | | | 0 | |
Issuance of restricted stock | | | 0 | |
Restricted stock forfeited | | | 0 | |
Stock-based compensation expense | | | 0 | |
Shares purchased and retired | | | (6,390) | |
Balance, June 30, 2018 | 143,921 | | 143,921 | |
Accumulated Other Comprehensive Loss [Member] | | | | |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | (17,859) | |
Foreign currency translation adjustments | | | (796) | |
Pension liability adjustment, net of tax | | | 236 | |
Cash dividends declared | | | 0 | |
Cash dividends paid to noncontrolling interest | | | 0 | |
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price | | | 0 | |
Issuance of restricted stock | | | 0 | |
Restricted stock forfeited | | | 0 | |
Stock-based compensation expense | | | 0 | |
Shares purchased and retired | | | 0 | |
Balance, June 30, 2018 | (18,419) | | (18,419) | |
Noncontrolling Interest [Member] | | | | |
Stockholders Equity Note [Line Items] | | | | |
Balance, December 31, 2017 | | | 7,122 | |
Net earnings | | | (274) | |
Foreign currency translation adjustments | | | (314) | |
Pension liability adjustment, net of tax | | | 0 | |
Cash dividends declared | | | 0 | |
Cash dividends paid to noncontrolling interest | | | (88) | |
Common stock issued under equity incentive plans, net of shares withheld for employee taxes and strike price | | | 0 | |
Issuance of restricted stock | | | 0 | |
Restricted stock forfeited | | | 0 | |
Stock-based compensation expense | | | 0 | |
Shares purchased and retired | | | 0 | |
Balance, June 30, 2018 | $ 6,446 | | $ 6,446 | |