Note 12 - Segment Information - Net Sales for Geographic Areas (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net sales	$ 24,502,272	$ 18,388,381	$ 19,280,770	$ 20,149,845	$ 24,100,498	$ 18,628,362	$ 19,552,905	$ 20,672,227	$ 82,321,268	$ 82,923,992	$ 84,161,200
UNITED STATES
Net sales									70,453,773	70,886,401	72,061,009
CANADA
Net sales									7,224,894	7,199,155	7,543,468
All Other Countries [Member]
Net sales									$ 4,642,601	$ 4,838,436	$ 4,556,723