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Goodwill and Intangible Assets - Intangible Assets by Major Asset Class (Detail) - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Intangible Assets By Major Class [Line Items]    
Gross $ 265,725 $ 265,725
Accumulated Amortization 40,767 39,967
Net Book Value 224,958 225,758
Patents    
Intangible Assets By Major Class [Line Items]    
Gross 31,581 31,581
Accumulated Amortization 31,530 31,491
Net Book Value $ 51 90
Patents | Minimum    
Intangible Assets By Major Class [Line Items]    
Useful Life (years) 2 years  
Patents | Maximum    
Intangible Assets By Major Class [Line Items]    
Useful Life (years) 16 years  
Other Intangible Assets    
Intangible Assets By Major Class [Line Items]    
Gross $ 15,780 15,780
Accumulated Amortization 9,237 8,476
Net Book Value $ 6,543 7,304
Other Intangible Assets | Minimum    
Intangible Assets By Major Class [Line Items]    
Useful Life (years) 1 year  
Other Intangible Assets | Maximum    
Intangible Assets By Major Class [Line Items]    
Useful Life (years) 9 years  
Trade name, trademark and trade dress and other    
Intangible Assets By Major Class [Line Items]    
Gross $ 218,364 218,364
Net Book Value $ 218,364 $ 218,364