Goodwill and Intangible Assets - Changes to Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 2,910	$ 2,910
Translation adjustment	(430)	(621)
Accumulated amortization	(1,736)	(1,320)
Balance	744	969
Trademark [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	300	300
Translation adjustment	(53)	(53)
Accumulated amortization	(247)	(247)
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,370	1,370
Translation adjustment	(198)	(298)
Accumulated amortization	(839)	(617)
Balance	333	455
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,240	1,240
Translation adjustment	(179)	(270)
Accumulated amortization	(650)	(456)
Balance	$ 411	$ 514