CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) (USD $)	Total	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), net [Member]
Balances at Mar. 31, 2013	$ 366,396,259	$ 89,789,789	$ 277,024,787	$ (418,317)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Proceeds from exercise of stock options, including tax benefits	13,662,510	13,662,510
Common stock repurchases	(190,536,775)		(190,536,775)
Issuance of restricted common stock under stock option plan	5,234,480	5,234,480
Stock option expense	9,678,724	9,678,724
Other comprehensive income	(3,687,809)			(3,687,809)
Net income	106,607,932		106,607,932
Balances at Mar. 31, 2014	307,355,321	118,365,503	193,095,944	(4,106,126)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Proceeds from exercise of stock options, including tax benefits	129,243	129,243
Common stock repurchases	(49,902,371)		(49,902,371)
Issuance of restricted common stock under stock option plan	1,672,572	1,672,572
Stock option expense	1,892,821	1,892,821
Other comprehensive income	592,105			592,105
Net income	22,555,335		22,555,335
Balances at Jun. 30, 2014	$ 284,295,026	$ 122,060,139	$ 165,748,908	$ (3,514,021)