Earnings Per Share (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Feb. 29, 2016 USD ($) $ / shares	Nov. 30, 2015 USD ($) $ / shares	Aug. 31, 2015 USD ($) $ / shares	May. 31, 2015 USD ($) $ / shares	Feb. 28, 2015 USD ($) $ / shares	Nov. 30, 2014 USD ($) $ / shares	Aug. 31, 2014 USD ($) $ / shares	May. 31, 2014 USD ($) $ / shares	Feb. 29, 2016 USD ($) $ / shares shares	Feb. 28, 2015 USD ($) $ / shares shares	Feb. 28, 2014 USD ($) $ / shares shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio									2
Numerator:
Net income | $	$ 16,076	$ 23,547	$ 17,243	$ 19,924	$ 16,283	$ 19,965	$ 13,769	$ 14,925	$ 76,790	$ 64,943	$ 59,597
Denominator:
Denominator for basic earnings per common share-weighted average shares (shares)									25,800,403	25,675,645	25,514,387
Effect of dilutive securities:
Employee and Director stock awards (shares)									136,780	102,300	179,081
Denominator for diluted earnings per common share (shares)									25,937,183	25,777,945	25,693,468
Earnings per share basic and diluted:
Basic earnings per common share (usd per share) | $ / shares	$ 0.62	$ 0.91	$ 0.67	$ 0.77	$ 0.63	$ 0.78	$ 0.54	$ 0.58	$ 2.98	$ 2.53	$ 2.34
Diluted earnings per common share (usd per share) | $ / shares	$ 0.62	$ 0.91	$ 0.67	$ 0.77	$ 0.63	$ 0.77	$ 0.53	$ 0.58	$ 2.96	$ 2.52	$ 2.32
Stock Appreciation Rights (SARs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount										80,683	113,887