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Revenue from Contracts with Customers - Narrative (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($) contract | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Minimum |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue recognition, contract term | 12 months |  |
Warranty, term | 1 year |  |
Maximum |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue recognition, contract term | 36 months |  |
Warranty, term | 2 years |  |
Transferred over Time | Product Concentration Risk | Revenue from Contract with Customer |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Concentration risk, percentage | 85.00% | 89.00% | 100.00%
Transferred at Point in Time | Product Concentration Risk | Revenue from Contract with Customer |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Concentration risk, percentage | 15.00% | 11.00% |
Heavy Civil Construction |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Number of contracts (more than) | contract | 150 |  |
Operating income (Loss) |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Estimated construction gain (loss) before tax | $ 7.1 | $ 0.9 | $ (6.3)
Costs and Estimated Earnings in Excess of Billings |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Contracts receivable unpaid project contract price | $ 9.3 | $ 10.0 |

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