Consolidated Statements of Earnings (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements of Earnings [Abstract]
Net sales	$ 161,521,993	$ 131,709,492
Costs and expenses:
Cost of products sold	143,915,520	114,401,307
Selling, general and administrative	5,491,737	5,251,610
Total costs and expenses	149,407,257	119,652,917
Total operating income (loss)	12,114,736	12,056,575
Interest and other income	91,824	57,138
EARNINGS BEFORE INCOME TAXES	12,206,560	12,113,713
Income taxes:
Current	4,146,796	3,835,780
Deferred	(90,700)	122,296
Total income taxes	4,056,096	3,958,076
NET EARNINGS	$ 8,150,464	$ 8,155,637
Weighted average number of common shares outstanding:
Basic	6,799,444	6,799,444
Diluted	6,799,444	6,799,444
Net earnings per share:
Basic	$ 1.20	$ 1.20
Diluted	$ 1.20	$ 1.20