Goodwill and Intangible Assets - Summary of Company's Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Cost	$ 12,167	$ 12,148
Accumulated amortization	(8,821)	(8,417)
Net carrying amount	3,346	3,731
Technology [Member]
Finite Lived Intangible Assets [Line Items]
Cost	5,770	5,770
Accumulated amortization	(5,770)	(5,770)
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Cost	5,647	5,628
Accumulated amortization	(2,301)	(1,897)
Net carrying amount	3,346	3,731
Non-Competition Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Cost	380	380
Accumulated amortization	(380)	(380)
Tradenames - Finite Life [Member]
Finite Lived Intangible Assets [Line Items]
Cost	370	370
Accumulated amortization	$ (370)	$ (370)