Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Deferred Tax Assets and Liabilities [Line Items]
Accounts receivable	$ 32	$ 470
Inventory	4,132	5,061
Accruals not currently deductible for tax purposes	8,641	3,729
Net operating loss and credit carryforwards	15,184	27,198
Capital loss carryforward	2,391	3,134
Depreciation	0	8,395
Equity compensation	3,658	5,134
Asset impairments	452	1,467
Other, net	2,549	4,356
Gross deferred tax assets	37,039	58,944
Valuation allowance	(17,494)	(14,661)
Total deferred tax assets	19,545	44,283
Purchased intangible assets	(28,956)	(55,809)
Depreciation	(2,512)	0
Gross deferred tax liabilities	(31,468)	(55,809)
Total deferred tax liabilities	$ (11,923)	$ (11,526)