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Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Accounting Policies and General Information [Line Items]          
Advertising expenses $ 0.8 $ 0.8 $ 2.4 $ 2.2  
Other Non-Current Assets [Member]          
Accounting Policies and General Information [Line Items]          
Retainage receivables 0.6   0.6    
Accounts Receivable [Member]          
Accounting Policies and General Information [Line Items]          
Retainage receivables $ 22.1   $ 22.1   $ 10.3