Earnings Per Share (Details) (USD $)	3 Months Ended		9 Months Ended
	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2014	Nov. 30, 2013
Numerator:
Net income for basic and diluted earnings per common share	$ 19,965,321	$ 18,445,155	$ 48,659,422	$ 49,354,707
Denominator:
Denominator for basic earnings per common share-weighted average shares (shares)	25,699,772	25,536,918	25,659,892	25,496,219
Effect of dilutive securities:
Employee and Director stock awards (shares)	93,794	182,960	103,928	186,887
Denominator for diluted earnings per common share (shares)	25,793,566	25,719,878	25,763,820	25,683,106
Earnings per share basic and diluted:
Basic earnings per Common share (usd per share)	$ 0.78	$ 0.72	$ 1.90	$ 1.94
Diluted earnings per common share (usd per share)	$ 0.77	$ 0.72	$ 1.89	$ 1.92