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Summary of Business and Significant Accounting Policies - Narrative (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 USD ($) reporting_unit segment | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Jan. 01, 2019 USD ($)
Financing Receivable, Impaired [Line Items] |  |  |  |
Ownership interest in joint venture, entity is consolidated | 50.00% |  |  |
Contract receivable retainage | $ 47,400,000 | $ 43,500,000 |  |
Unbilled contracts receivable | 0 | 0 |  |
Allowance for doubtful accounts | 0 | 0 |  |
Inventories | 3,159,000 | 4,621,000 |  |
Depreciation | 14,200,000 | 15,100,000 | $ 15,700,000 |
Capital lease obligations | 200,000 | 300,000 |  |
Impairment long-lived assets | $ 0 | 0 | 0 |
Number of reportable segments | segment | 2 |  |  |
Number of reporting units | reporting_unit | 2 |  |  |
Operating leases, remaining terms | 4 years |  |  |
Retainage estimated to collect | 75.00% |  |  |
Costs and Estimated Earnings in Excess of Billings |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Unpaid project contract price | $ 9,300,000 | 10,000,000 |  |
Minimum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Revenue recognition, percentage of completion range | 12 months |  |  |
Warranty term | 1 year |  |  |
Lessee, operating lease, discount rate | 5.00% |  |  |
Maximum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Revenue recognition, percentage of completion range | 36 months |  |  |
Warranty term | 2 years |  |  |
Lessee, operating lease, discount rate | 8.00% |  |  |
JBC Former Owners |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Business acquisition earn-out expense |  | 1,300,000 | $ 1,200,000 |
Tealstone |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Business acquisition earn-out expense | $ 1,600,000 | $ 400,000 |  |
Building and improvements | Minimum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Property, plant and equipment, useful life | 5 years |  |  |
Building and improvements | Maximum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Property, plant and equipment, useful life | 39 years |  |  |
Plant and field equipment | Minimum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Property, plant and equipment, useful life | 5 years |  |  |
Plant and field equipment | Maximum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Property, plant and equipment, useful life | 15 years |  |  |
Forecast | Subsequent Event | Minimum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Operating lease, right-of-use asset |  |  |  | $ 14,000,000
Operating lease, right-of-use liability |  |  |  | 14,000,000
Forecast | Subsequent Event | Maximum |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |
Operating lease, right-of-use asset |  |  |  | 16,000,000
Operating lease, right-of-use liability |  |  |  | $ 16,000,000

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