Note 1 - Summary of Significant Interim Accounting Policies - Adjustments to Retained Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Net sales	$ 82,392	$ 65,604	$ 155,479	$ 126,591
Cost of goods sold	53,114	42,230	101,326	81,003
Selling and administrative expenses	23,327	16,994	44,509	34,423
Income before taxes on income	5,097	5,701	8,417	11,106
Income tax expense	1,280	$ 1,360	2,150	$ 2,930
Adjustment to opening retained earnings	97,664		97,664		$ 83,129
Accounting Standards Update 2014-09 [Member]
Net sales			42,880
Cost of goods sold			27,397
Selling and administrative expenses			706
Income before taxes on income			14,777
Income tax expense			3,542
Adjustment to opening retained earnings	$ 11,235		$ 11,235