Note 4 - Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Dividends and dividend equivalents	$ 21,895	$ 15,044
Stock rotation and sales returns	7,884	5,363
Customer prepayments	4,160	2,520
Income tax payable	2,778	7,018
Operating lease liabilities	1,318	0
Warranty	1,267	4,564
Commissions	976	1,369
Other	5,706	3,084
Total	$ 45,984	$ 38,962