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, 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	7,530,624	7,530,624
Common stock repurchases	(115,324,097)		(115,324,097)
Issuance of restricted common stock under stock option plan	7,834,825	7,834,825
Stock option expense	8,133,812	8,133,812
Other comprehensive income	(10,796,224)			(10,796,224)
Net income	110,833,458		110,833,458
Balances at Mar. 31, 2015	315,567,719	141,864,764	188,605,305	(14,902,350)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Proceeds from exercise of stock options, including tax benefits	2,859,649	2,859,649
Issuance of restricted common stock under stock option plan	(7,892,467)	(7,892,467)
Stock option expense	3,226,766	3,226,766
Other comprehensive income	(8,461,239)			(8,461,239)
Net income	57,569,828		57,569,828
Balances at Dec. 31, 2015	$ 362,870,256	$ 140,058,712	$ 246,175,133	$ (23,363,589)