Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

v3.7.0.1
Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Changes in the Allowance for Doubtful Accounts [Roll Forward]            
Allowance for doubtful accounts, beginning of period $ 5,957,000   $ 3,729,000 $ 7,836,000 $ 3,729,000 $ 3,729,000
Charges to costs and expenses       15,000 1,852,000  
Account write-offs and other       (3,945,000) 376,000  
Allowance for doubtful accounts, end of period   $ 5,957,000   3,906,000 $ 5,957,000 7,836,000
Loss contingency, additional exposure       0    
Contracts receivable retainage allowances and reserves       $ 547,000   $ 887,000
Canada            
Changes in the Allowance for Doubtful Accounts [Roll Forward]            
Allowance for doubtful accounts receivable, period increase   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 $ 2,194,000 1,655,000 200,000      
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            
Changes in the Allowance for Doubtful Accounts [Roll Forward]            
Allowance for doubtful accounts receivable, period increase   $ 279,000