Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2014	Aug. 31, 2013
Numerator:
Net income for basic and diluted earnings per common share	$ 13,768,710	$ 16,362,769	$ 28,694,101	$ 30,909,552
Denominator:
Denominator for basic earnings per common share-weighted average shares (shares)	25,656,945	25,487,796	25,639,952	25,475,869
Effect of dilutive securities:
Employee and Director stock awards (shares)	101,229	176,312	108,995	188,851
Denominator for diluted earnings per common share (shares)	25,758,174	25,664,108	25,748,947	25,664,720
Earnings per share basic and diluted:
Basic earnings per Common share (usd per share)	$ 0.54	$ 0.64	$ 1.12	$ 1.21
Diluted earnings per common share (usd per share)	$ 0.53	$ 0.64	$ 1.11	$ 1.20