Note 4 - Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Dividends and dividend equivalents	$ 31,679	$ 26,435
Stock rotation and sales returns	5,207	6,005
Accrued purchases of property and equipment	739	5,841
Income tax payable	3,959	3,755
Customer prepayments	7,383	7,238
Commissions	1,162	1,107
Warranty	10,873	6,895
Other	5,359	4,278
Total	68,570	62,960
Accrued Liabilities, Current [Member]
Operating lease liabilities	$ 2,209	$ 1,406