Note 13 - Quarterly Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Net sales	$ 71,914	$ 72,404	$ 75,706	$ 72,963	$ 63,342	$ 62,806	$ 66,665	$ 64,379
Gross profit	50,633	50,713	51,293	50,971	43,999	43,458	46,502	44,933
Income from operations	6,927	6,666	8,438	7,195	3,789	3,706	7,120	6,961
Net loss	$ 3,786	$ 3,761	$ 4,490	$ 3,659	$ 1,506	$ 1,504	$ 3,828	$ 3,709
Basic (in dollars per share)	$ 0.08	$ 0.07	$ 0.09	$ 0.07	$ 0.03	$ 0.03	$ 0.08	$ 0.07
Diluted (in dollars per share)	$ 0.08	$ 0.07	$ 0.09	$ 0.07	$ 0.03	$ 0.03	$ 0.07	$ 0.07