Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowances and reserves	$ 259	$ 705
Accrued expenses	1,808	1,452
Inventory reserves	4,443	7,071
Net operating loss carryforwards	35,975	37,444
Property and equipment	1,249	2,730
Intangible asset	2,046	3,291
Stock-based compensation	1,542	1,766
Legal settlement	6,881	11,494
Goodwill	1,755	3,029
Income tax credit carryforwards	3,326	5,429
Total deferred tax assets	59,284	74,411
Valuation allowance	(44,389)	(58,202)
Total deferred tax assets, net of valuation allowance	14,895	16,209
Deferred tax liabilities:
Investment in foreign partnership	14,859	16,215
Total deferred tax liabilities	14,859	16,215
Net deferred tax assets (liabilities)	$ 36
Net deferred tax assets (liabilities)		$ (6)