Note 4 - Balance Sheet Components (Details) - Accrued Liabilities (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	$ 18,626	$ 14,703
Dividends and Dividend Equivalents [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	8,196	6,080
Deferred Revenue And Customer Prepayments [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	5,073	3,908
Stock Rotation Reserve [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	2,376	1,757
Commissions [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	833	767
Deferred Compensation Plan [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	704
Sales Rebate [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	337	586
Warranty [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	296	240
Other Liability [Member]
Note 4 - Balance Sheet Components (Details) - Accrued Liabilities [Line Items]
Accrued liabilities	$ 811	$ 1,365