Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies- Accounts Receivable (Details)

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Summary of Significant Accounting Policies- Accounts Receivable (Details) - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2016
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Allowance for doubtful accounts, beginning of period   $ 3,729,000 $ 2,851,000 $ 2,851,000
Charges to costs and expenses   1,852,000 83,000  
Account write-offs and other   376,000 (256,000)  
Allowance for doubtful accounts, end of period $ 5,957,000 5,957,000 $ 2,678,000 3,729,000
Asset retirement obligation       0
Loss contingency, additional exposure 2,952,000 $ 2,952,000    
Contracts receivable retainage allowances and reserves       $ 1,282,000
Canada | Operating Segments        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Bad debt expense 1,934,000      
Minimum        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Accounts receivable retainage   5.00%    
Maximum        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Accounts receivable retainage   10.00%    
Accounts Receivable        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Allowance for doubtful accounts receivable, period increase   $ 200,000    
Bad debt expense 1,655,000      
Reclassification adjustment recorded during 2015   (1,021,000)    
Costs in Excess of Billings        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Allowance for doubtful accounts receivable, period increase   476,000    
Construction in Progress, Gross        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Allowance for doubtful accounts receivable, period increase   $ 325,000    
Contract Receivable Retainage, Net        
Changes in the Allowance for Doubtful Accounts [Roll Forward]        
Bad debt expense $ 279,000