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, 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) 0 (69,288)
Net income       13,360,945 13,360,945
Comprehensive income         13,291,657
Stock-based compensation 0 76,720 0 0 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
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        
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 (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