Goodwill and Intangible Assets - Summary of Company's Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Cost	$ 12,175	$ 12,167
Accumulated amortization	(8,925)	(8,821)
Net carrying amount	3,250	3,346
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	5,655	5,647
Accumulated amortization	(2,405)	(2,301)
Net carrying amount	3,250	3,346
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)