Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Intangible assets and goodwill	$ 2,271	$ 2,628
Inventories and related reserves	11,298	17,665
Deferred revenue and cost of goods sold	6,816	11,263
Other accruals and reserves	2,336	4,066
Accrued compensation	4,054	6,747
Allowance for doubtful accounts	2,617	2,898
Accrued interest		4,621
Net operating loss carryforwards	42,675	37,930
Other, net	2,369	3,032
Total	74,436	90,850
Valuation allowance	(46,271)	(41,701)
Deferred tax asset	28,165	49,149
Withholding taxes	381	648
Property, plant and equipment	(4,469)	(1,176)
Deferred tax liability	(4,850)	(1,824)
Net deferred tax assets	$ 23,315	$ 47,325