Goodwill and Intangible Assets - Summary of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Cost	$ 34,334	$ 34,334
Accumulated Amortization	32,511	32,221
Net Book Value	1,823	2,113
Customer Contracts and Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Cost	16,880	16,880
Accumulated Amortization	16,880	16,880
Net Book Value	0	0
Patents and Technology [Member]
Finite Lived Intangible Assets [Line Items]
Cost	10,114	10,114
Accumulated Amortization	8,837	8,670
Net Book Value	1,277	1,444
Trademarks and Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Cost	4,834	4,834
Accumulated Amortization	4,422	4,335
Net Book Value	412	499
Other [Member]
Finite Lived Intangible Assets [Line Items]
Cost	2,506	2,506
Accumulated Amortization	2,372	2,336
Net Book Value	$ 134	$ 170