Quarterly Data - Quarterly Data (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 24,666,000	$ 30,008,000	$ 33,396,000	$ 19,152,000	$ 21,379,000	$ 22,135,000	$ 28,412,000	$ 17,651,000	$ 107,222,306	$ 89,576,777
Cost of goods sold	15,694,000	19,393,000	21,675,000	12,275,000	14,004,000	14,195,000	18,330,000	11,224,000	69,036,695	57,752,733
Net income	$ 689,000	$ 1,189,000	$ 2,543,000	$ 368,000	$ 524,000	$ 959,000	$ 2,211,000	$ 309,000	$ 4,789,005	$ 4,002,905
Basic earnings per share	$ 0.21	$ 0.37	$ 0.79	$ 0.12	$ 0.16	$ 0.30	$ 0.70	$ 0.10	$ 1.48	$ 1.26
Diluted earnings per share	$ 0.19	$ 0.34	$ 0.72	$ 0.11	$ 0.15	$ 0.29	$ 0.68	$ 0.10	$ 1.36	$ 1.22
Dividends per share	$ 0.09	$ 0.09	$ 0.08	$ 0.08	$ 0.08	$ 0.08	$ 0.08	$ 0.07	$ 0.34	$ 0.31