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Segments - Additional Information (Detail)
3 Months Ended
Mar. 31, 2018
USD ($)
segment
Mar. 31, 2017
USD ($)
Segment Reporting Information [Line Items]    
Number of reportable segments | segment 2  
Revenues, net $ 585,500,000 $ 520,433,000
Intersegment Eliminations    
Segment Reporting Information [Line Items]    
Revenues, net $ 0