Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating losses	$ 23,926,000	$ 25,418,000
Foreign tax credits	16,800,000	21,346,000
Accruals	4,242,000	5,921,000
Stock-based compensation	3,173,000	3,023,000
Property and equipment	2,008,000	1,111,000
Accounts receivable	1,980,000	2,124,000
Goodwill and other intangibles	1,296,000	4,717,000
Deferred revenue	1,016,000	600,000
Inventories	133,000	1,930,000
Other	2,487,000	335,000
Gross deferred tax assets	57,061,000	66,525,000
Valuation allowances	(40,630,000)	(45,995,000)	$ (30,972,000)
Total deferred tax assets	16,431,000	20,530,000
Deferred tax liabilities:
Inventories	(4,885,000)
Accrued withholding tax	(1,303,000)	(1,452,000)
Goodwill and other intangibles	(1,202,000)	(1,587,000)
Other	(1,757,000)	(1,144,000)
Total deferred tax liabilities	(9,147,000)	(4,183,000)
Net deferred tax assets	$ 7,284,000	$ 16,347,000