Annual report pursuant to Section 13 and 15(d)

Intangible Assets - Summary of Intangible Assets (Detail)

v3.10.0.1
Intangible Assets - Summary of Intangible Assets (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Cost of intangible assets gross $ 25,027 $ 25,027 $ 25,027
Accumulated amortization, beginning balance (13,449) (11,623)  
Amortization expense (1,685) (1,826) (1,927)
Accumulated amortization, ending balance (15,134) (13,449) (11,623)
Net book value $ 9,893 11,578  
Minimum      
Useful lives 3 years    
Maximum      
Useful lives 20 years    
Customer Relationships      
Cost of intangible assets gross $ 22,560 22,560 22,560
Accumulated amortization, beginning balance (11,367) (9,721)  
Amortization expense (1,520) (1,646)  
Accumulated amortization, ending balance (12,887) (11,367) (9,721)
Net book value $ 9,673 $ 11,193  
Customer Relationships | Minimum      
Useful lives 10 years 10 years  
Customer Relationships | Maximum      
Useful lives 20 years 20 years  
Other Intangible Assets      
Cost of intangible assets gross $ 2,467 $ 2,467 2,467
Accumulated amortization, beginning balance (2,082) (1,902)  
Amortization expense (165) (180)  
Accumulated amortization, ending balance (2,247) (2,082) $ (1,902)
Net book value $ 220 $ 385  
Other Intangible Assets | Minimum      
Useful lives 3 years 3 years  
Other Intangible Assets | Maximum      
Useful lives 5 years 5 years