Earnings Per Share (Details) (USD $)	3 Months Ended		9 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2013	Nov. 30, 2012
Numerator:
Net income for basic and diluted earnings per common share	$ 18,445,155	$ 15,363,680	$ 49,354,707	$ 47,222,557
Denominator:
Denominator for basic earnings per common share-weighted average shares (shares)	25,536,918	25,362,450	25,496,219	25,301,207
Effect of dilutive securities:
Employee and Director stock awards (shares)	182,960	240,412	186,887	236,050
Denominator for diluted earnings per common share (shares)	25,719,878	25,602,862	25,683,106	25,537,257
Earnings per share basic and diluted:
Basic earnings per Common share (usd per share)	$ 0.72	$ 0.61	$ 1.94	$ 1.87
Diluted earnings per common share (usd per share)	$ 0.72	$ 0.60	$ 1.92	$ 1.85