Statements of Shareholders Equity (USD $)	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Balance at Mar. 31, 2009	$ 46,693	$ 19,166,524	$ (252,940)	$ 22,607,294	$ 41,567,571
Balance, shares at Mar. 31, 2009	4,669,333
Exercise of stock options and warrants	313	622,110	0	0	622,423
Exercise of stock options and warrants, shares	31,250
Comprehensive income:
Unrealized (loss) on marketable securities, net of tax	0	0	1,382,666	0	1,382,666
Net income				11,999,344	11,999,344
Total comprehensive income					13,382,010
Stock-based compensation	0	100,842	0	0	100,842
Tax benefit of stock-based compensation		280,448			280,448
Balance at Mar. 31, 2010	47,006	20,169,924	1,129,726	34,606,638	55,953,294
Balance, Shares at Mar. 31, 2010	4,700,583
Exercise of stock options and warrants	756	417,949	0	0	418,705
Exercise of stock options and warrants, shares	75,615
Comprehensive income:
Unrealized (loss) on marketable securities, net of tax	0	0	(69,288)		(69,288)
Net income	0	0	0	13,360,945	13,360,945
Total comprehensive income					13,291,657
Stock-based compensation		76,720			76,720
Tax benefit of stock-based compensation		230,173			230,173
Balance at Mar. 31, 2011	47,762	20,894,766	1,060,438	47,967,583	69,970,549
Balance, Shares at Mar. 31, 2011	4,776,198
Exercise of stock options and warrants	485	(449)	0	0	36
Exercise of stock options and warrants, shares	48,547
Comprehensive income:
Unrealized (loss) on marketable securities, net of tax	0	0	27,018		27,018
Net income	0	0	0	11,381,095	11,381,095
Total comprehensive income					11,408,113
Stock-based compensation		80,160			80,160
Balance at Mar. 31, 2012	$ 48,247	$ 20,974,477	$ 1,087,456	$ 59,348,678	$ 81,458,858
Balance, Shares at Mar. 31, 2012	4,824,745