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 ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2016
Changes in the Allowance for Doubtful Accounts [Roll Forward]      
Allowance for doubtful accounts, beginning of period $ 3,315 $ 7,836  
Charges to costs and expenses 64 0  
Account write-offs and other (86) (463)  
Allowance for doubtful accounts, end of period $ 3,293 $ 7,373 $ 7,836
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     $ 2,394