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Summary of Business and Significant Accounting Policies - Narrative (Details)
 12 Months Ended
Dec. 31, 2017
USD ($)
reporting_unit
segment
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Financing Receivable, Impaired [Line Items]      
Ownership interest in joint venture, entity is consolidated 50.00%    
Contract receivable retainage $ 43,500,000 $ 23,400,000  
Unbilled contracts receivable 0 0  
Provision for doubtful accounts 0 0 $ 0
Allowance for doubtful accounts 0 0  
Inventories 4,621,000 3,708,000  
Depreciation 15,100,000 15,700,000 16,200,000
Capital lease obligations 300,000 400,000  
Impairment of long-lived assets $ 0 0 0
Number of reportable segments | segment 2    
Number of reporting units | reporting_unit 2    
Costs and Estimated Earnings in Excess of Billings      
Financing Receivable, Impaired [Line Items]      
Unapproved change orders $ 5,000,000 2,200,000  
Claims 5,000,000 9,200,000  
Unpaid project contract price 0 3,900,000  
Operating Income (Loss)      
Financing Receivable, Impaired [Line Items]      
Estimated construction gross profit (loss), before tax $ 900,000 (6,300,000) $ (9,700,000)
Minimum      
Financing Receivable, Impaired [Line Items]      
Revenue recognition, percentage of completion range 12 months    
Warranty term 1 year    
Minimum | Notes Payable for Transportation and Construction Equipment      
Financing Receivable, Impaired [Line Items]      
Debt instrument, term 2 years    
Stated interest rate 3.15%    
Maximum      
Financing Receivable, Impaired [Line Items]      
Revenue recognition, percentage of completion range 36 months    
Warranty term 2 years    
Maximum | Notes Payable for Transportation and Construction Equipment      
Financing Receivable, Impaired [Line Items]      
Debt instrument, term 5 years    
Stated interest rate 6.92%    
JBC Former Owners      
Financing Receivable, Impaired [Line Items]      
Business acquisition earn-out expense   1,200,000  
JBC Former Owners | Other Operating Income (Expense)      
Financing Receivable, Impaired [Line Items]      
Business acquisition earn-out expense $ 1,300,000    
Tealstone      
Financing Receivable, Impaired [Line Items]      
Business acquisition earn-out expense $ 400,000    
Residential Construction      
Financing Receivable, Impaired [Line Items]      
Revenue recognition, percentage of completion range 1 month    
Notes Payable for Transportation and Construction Equipment      
Financing Receivable, Impaired [Line Items]      
Notes payable for transportation and construction equipment and other $ 1,557,000 $ 2,665,000  
Notes Payable for Transportation and Construction Equipment | Minimum      
Financing Receivable, Impaired [Line Items]      
Debt instrument, term 3 years    
Stated interest rate 3.15%    
Notes Payable for Transportation and Construction Equipment | Maximum      
Financing Receivable, Impaired [Line Items]      
Debt instrument, term 5 years    
Stated interest rate 6.92%