Quarterly Data - Quarterly Data (Details) - USD ($)	3 Months Ended								12 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	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 23,118,000	$ 29,903,000	$ 33,954,000	$ 22,837,000	$ 24,666,000	$ 30,008,000	$ 33,396,000	$ 19,152,000	$ 109,811,768	$ 107,222,306
Cost of goods sold	14,852,000	19,578,000	21,419,000	14,402,000	15,694,000	19,393,000	21,675,000	12,275,000	70,250,550	69,036,695
Net income	$ 440,000	$ 1,208,000	$ 2,710,000	$ 436,000	$ 689,000	$ 1,189,000	$ 2,543,000	$ 368,000	$ 4,793,525	$ 4,789,005
Basic earnings per share	$ .12	$ .36	$ .82	$ .13	$ .21	$ .37	$ .79	$ .12	$ 1.44	$ 1.48
Diluted earnings per share	.11	.33	.74	.12	.19	.34	.72	.11	1.30	1.36
Dividends per share	$ .10	$ .09	$ .09	$ .09	$ .09	$ .09	$ .08	$ .08	$ .37	$ .34