Income Taxes (Detail) - Deferred tax assets and deferred tax liabilities: (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Research and development credits	$ 1,707	$ 1,658
Other credits	347	985
Operating loss carry forwards	10,562	8,428
Inventories	469	370
Allowance for doubtful accounts	563	107
Depreciation	246	107
Deferred research and development expenses for income tax	327	331
Non-cash compensation	706	546
Other	536	617
Total gross deferred tax assets	15,463	13,149
Valuation allowance	(14,906)	(12,603)
Net deferred tax assets	557	546
Deferred tax liabilities
Other identifiable intangible assets	(1,354)	(1,488)
Total gross deferred tax liabilities	(1,354)	(1,488)
Net deferred tax liabilities	$ (797)	$ (942)