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, 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 gain (loss) on marketable securities, net of tax	0	0	27,018	0	27,018
Net income				11,381,095	11,381,095
Comprehensive income					11,408,113
Stock-based compensation	0	80,160	0	0	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
Exercise of stock options and warrants	377	143,811	0	0	144,188
Exercise of stock options and warrants, shares	37,691
Comprehensive income:
Unrealized gain (loss) on marketable securities, net of tax	0	0	470,270		470,270
Net income	0	0	0	11,828,838	11,828,838
Comprehensive income					12,299,108
Stock-based compensation		66,720			66,720
Tax benefit of stock-based compensation		15,734			15,734
Balance at Mar. 31, 2013	48,624	21,200,742	1,557,726	71,177,516	93,984,608
Balance, Shares at Mar. 31, 2013	4,862,436
Exercise of stock options and warrants	140	416,620	0	0	416,760
Exercise of stock options and warrants, shares	14,000
Repurchase of common stock	(254)	(1,263,151)			(1,263,405)
Repurchase of common stock, shares	(25,393)				(25,393)
Comprehensive income:
Unrealized gain (loss) on marketable securities, net of tax	0	0	(679,869)		(679,869)
Net income	0	0	0	11,135,875	11,135,875
Comprehensive income					10,456,006
Stock-based compensation		53,200			53,200
Tax benefit of stock-based compensation		57,472			57,472
Balance at Mar. 31, 2014	$ 48,510	$ 20,464,883	$ 877,857	$ 82,313,391	$ 103,704,641
Balance, Shares at Mar. 31, 2014	4,851,043