Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets, Net - Summary of Intangible Assets (Detail)

v3.8.0.1
Intangible Assets, Net - Summary of Intangible Assets (Detail) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Cost, beginning balance $ 25,027 $ 25,027 $ 25,027
Cost, ending balance 25,027   25,027
Accumulated amortization, beginning balance (13,449) (11,623) (11,623)
Amortization expense (425) (457) (1,826)
Accumulated amortization, ending balance (13,874)   (13,449)
Net book value $ 11,153   11,578
Minimum      
Useful lives 3 years    
Maximum      
Useful lives 20 years    
Customer Relationships      
Cost, beginning balance $ 22,560 22,560 22,560
Cost, ending balance 22,560   22,560
Accumulated amortization, beginning balance (11,367) (9,721) (9,721)
Amortization expense (380)   (1,646)
Accumulated amortization, ending balance (11,747)   (11,367)
Net book value $ 10,813   $ 11,193
Customer Relationships | Minimum      
Useful lives 10 years   10 years
Customer Relationships | Maximum      
Useful lives 20 years   20 years
Other Intangible Assets      
Cost, beginning balance $ 2,467 2,467 $ 2,467
Cost, ending balance 2,467   2,467
Accumulated amortization, beginning balance (2,082) $ (1,902) (1,902)
Amortization expense (45)   (180)
Accumulated amortization, ending balance (2,127)   (2,082)
Net book value $ 340   $ 385
Other Intangible Assets | Minimum      
Useful lives 3 years   3 years
Other Intangible Assets | Maximum      
Useful lives 5 years   5 years