Consolidated Statements of Shareholders' Equity - USD ($)	Common stock	Treasury stock	Additional paid-in capital	Retained earnings	Total
Balance at Mar. 31, 2015	$ 580,575		$ 844,539,059	$ 28,094,625	$ 873,214,259
Balance (in shares) at Mar. 31, 2015	58,057,493
Increase (Decrease) in Shareholders' Equity
Net income/(loss)				129,688,382	129,688,382
Stock-based compensation			3,640,412		3,640,412
Purchase of treasury stock		$ (20,943,816)			(20,943,816)
Balance at Mar. 31, 2016	$ 580,575	(20,943,816)	848,179,471	157,783,007	985,599,237
Balance (in shares) at Mar. 31, 2016	58,057,493
Increase (Decrease) in Shareholders' Equity
Net income/(loss)				(1,441,815)	(1,441,815)
Restricted share award issuances	$ 2,847		(2,847)
Restricted share award issuances (in shares)	284,708
Stock-based compensation			4,797,749		4,797,749
Purchase of treasury stock		(12,953,453)			(12,953,453)
Balance at Mar. 31, 2017	$ 583,422	(33,897,269)	852,974,373	156,341,192	976,001,718
Balance (in shares) at Mar. 31, 2017	58,342,201
Increase (Decrease) in Shareholders' Equity
Net income/(loss)				(20,400,686)	(20,400,686)
Restricted share award issuances	$ 2,980		(2,980)
Restricted share award issuances (in shares)	297,960
Stock-based compensation			5,138,489		5,138,489
Purchase of treasury stock		(1,326,159)			(1,326,159)
Balance at Mar. 31, 2018	$ 586,402	$ (35,223,428)	$ 858,109,882	$ 135,940,506	$ 959,413,362
Balance (in shares) at Mar. 31, 2018	58,640,161