Note 7 - Segment Information - Net Sales for Geographic Areas (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
UNITED STATES
Net sales	$ 15,955,084	$ 16,558,873	$ 50,293,346	$ 51,144,236
CANADA
Net sales	1,597,652	1,693,958	5,085,955	5,432,724
All Other Countries [Member]
Net sales	1,075,626	1,103,106	3,444,193	3,341,269
Net sales	$ 18,628,362	$ 19,355,937	$ 58,823,494	$ 59,918,229