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Retirement Plans - Narrative (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 USD ($) plan | Dec. 31, 2018 USD ($) | Dec. 31, 2017 plan
Defined Benefit Plan Disclosure |  |  |
Net loss to be recognize during the next fiscal period | $ 47 |  |
United States |  |  |
Defined Benefit Plan Disclosure |  |  |
Defined benefit plans, estimated future employer contributions in current fiscal year | $ 660 |  |
Pension Plan |  |  |
Defined Benefit Plan Disclosure |  |  |
Defined contribution plan number | plan | 6 |  |
Pension Plan | United States |  |  |
Defined Benefit Plan Disclosure |  |  |
Number of retirement plans | plan | 3 |  |
Number of defined benefit plans | plan | 1 |  |
Defined contribution plan number | plan | 2 |  |
Accrued pension obligation | $ 3,449 | $ 4,249 |
Defined benefit plan, contributions | $ 550 | 0 |
Pension Plan | Canada |  |  |
Defined Benefit Plan Disclosure |  |  |
Defined contribution plan number | plan | 2 |  |
Pension Plan | United Kingdom |  |  |
Defined Benefit Plan Disclosure |  |  |
Number of defined benefit plans | plan |  |  | 0
Defined contribution plan number | plan | 2 |  |
Defined benefit plans, estimated future employer contributions in current fiscal year | $ 318 |  |
Accrued pension obligation | 1,811 | 1,403 |
Defined benefit plan, contributions | $ 314 | 271 |
Other Postretirement Benefits Plan |  |  |
Defined Benefit Plan Disclosure |  |  |
Service period | 10 years |  |
Other Postretirement Benefits Plan | Rail Technologies |  |  |
Defined Benefit Plan Disclosure |  |  |
Accrued pension obligation | $ 840 | $ 724 |

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