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Summary of Significant Accounting Policies (Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts) - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Receivables [Abstract]    
Number of days after accounts receivable are treated as delinquent 30 days  
Number of days related to outstanding accounts receivable for analysis of the allowance for doubtful accounts At least 90 days  
Allowances for doubtful accounts on current receivable $ 5,008 $ 2,752
Current retainage balances 253,000 231,000
Non-current retainage balances 9,400 5,200
Unbilled receivables $ 296,700 $ 206,800