Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	$ 58,170	$ 60,515
Accumulated amortization	(54,204)	(56,454)
Intangible asset, Net amount	3,966	4,061
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	19,288	20,194
Accumulated amortization	(19,288)	(20,194)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	27,702	29,002
Accumulated amortization	(27,702)	(29,002)
Intellectual Property Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	11,180	11,319
Accumulated amortization	(7,214)	(7,258)
Intangible asset, Net amount	$ 3,966	$ 4,061