Note 14 - Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Sales	$ 24,100,498	$ 18,628,362	$ 19,552,905	$ 20,672,227	$ 24,292,971	$ 19,355,937	$ 19,773,528	$ 20,788,764	$ 82,923,992	$ 84,161,200	$ 83,430,912
Gross Profit	14,519,835	11,644,871	12,895,790	12,652,746	14,841,054	11,832,697	12,814,382	12,582,927	51,713,242	52,071,060	52,124,757
Net income	$ 2,059,997	$ 1,000,350	$ 1,820,915	$ 1,520,997	$ 2,338,758	$ 1,111,344	$ 1,507,896	$ 1,444,407	$ 6,402,259	$ 6,402,405	$ 7,706,921
NET INCOME PER COMMON SHARE:
BASIC (in dollars per share)	$ 0.23	$ 0.11	$ 0.19	$ 0.16	$ 0.24	$ 0.11	$ 0.15	$ 0.14	$ 0.69	$ 0.64	$ 0.76
Earnings per share - diluted (in dollars per share)	0.23	0.11	0.19	0.16	0.24	0.11	0.15	0.14	0.69	0.63	0.75
Earnings per share – basic (in dollars per share)	$ 0.23	$ 0.11	$ 0.19	$ 0.16	$ 0.24	$ 0.11	$ 0.15	$ 0.14	$ 0.69	$ 0.64	$ 0.76
Weighted average number of common shares outstanding:
Basic (in shares)	9,188,483	9,188,483	9,209,446	9,698,951	9,692,860	10,175,650	10,212,933	10,211,333	9,301,867	10,077,506	10,203,063
Diluted (in shares)	9,301,867	9,206,382	9,227,941	9,718,453	9,712,571	10,199,092	10,241,164	10,241,096	9,321,558	10,102,760	10,241,121
Net Sales	$ 24,100,498	$ 18,628,362	$ 19,552,905	$ 20,672,227	$ 24,292,971	$ 19,355,937	$ 19,773,528	$ 20,788,764	$ 82,923,992	$ 84,161,200	$ 83,430,912
Gross Profit	14,519,835	11,644,871	12,895,790	12,652,746	14,841,054	11,832,697	12,814,382	12,582,927	51,713,242	52,071,060	52,124,757
Net income	$ 2,059,997	$ 1,000,350	$ 1,820,915	$ 1,520,997	$ 2,338,758	$ 1,111,344	$ 1,507,896	$ 1,444,407	$ 6,402,259	$ 6,402,405	$ 7,706,921