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 9 Months Ended 12 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Cost, beginning balance     $ 25,027 $ 25,027 $ 25,027
Cost, ending balance $ 25,027   25,027   25,027
Accumulated amortization, beginning balance     (11,623) (9,696) (9,696)
Amortization expense (456) $ (486) (1,369) (1,459) (1,927)
Accumulated amortization, ending balance (12,992)   (12,992)   (11,623)
Net book value 12,035   $ 12,035   13,404
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   22,560
Accumulated amortization, beginning balance     (9,721) (8,062) (8,062)
Amortization expense     (1,234)   (1,659)
Accumulated amortization, ending balance (10,955)   (10,955)   (9,721)
Net book value 11,605   $ 11,605   $ 12,839
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   2,467
Accumulated amortization, beginning balance     (1,902) $ (1,634) (1,634)
Amortization expense     (135)   (268)
Accumulated amortization, ending balance (2,037)   (2,037)   (1,902)
Net book value $ 430   $ 430   $ 565
Other Intangible Assets | Minimum          
Useful lives     3 years   3 years
Other Intangible Assets | Maximum          
Useful lives     5 years   5 years