Share-Based Compensation Plans (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2014 SG&A	Aug. 31, 2013 SG&A	Aug. 31, 2014 SG&A	Aug. 31, 2013 SG&A	Aug. 31, 2014 Employee stock options	Aug. 31, 2014 Employee stock options	Aug. 31, 2014 Employee stock options SG&A	Aug. 31, 2013 Employee stock options SG&A	Aug. 31, 2014 Employee stock options SG&A	Aug. 31, 2013 Employee stock options SG&A	Aug. 31, 2014 Employee stock options Minimum	Aug. 31, 2014 Employee stock options Maximum	Aug. 31, 2014 Stock compensation Directors SG&A	Aug. 31, 2013 Stock compensation Directors SG&A	Aug. 31, 2014 Stock compensation Directors SG&A	Aug. 31, 2013 Stock compensation Directors SG&A	Aug. 31, 2014 Performance-based and other stock awards SG&A	Aug. 31, 2013 Performance-based and other stock awards SG&A	Aug. 31, 2014 Performance-based and other stock awards SG&A	Aug. 31, 2013 Performance-based and other stock awards SG&A	Aug. 31, 2014 Restricted stock awards Directors	Aug. 31, 2014 Restricted stock awards Directors	May 31, 2014 Restricted stock awards Former CEO Performance-based	May 31, 2014 Stock units Former CEO Performance-based	Aug. 31, 2014 Directors stock options	Aug. 31, 2014 Directors stock options	Aug. 31, 2014 Employee stock purchase plan	Aug. 31, 2014 Employee stock purchase plan SG&A	Aug. 31, 2013 Employee stock purchase plan SG&A	Aug. 31, 2014 Employee stock purchase plan SG&A	Aug. 31, 2013 Employee stock purchase plan SG&A	May 31, 2014 Performance-based stock awards Former CEO
Share-based compensation plans
Options granted (in shares)									9,000	240,500
Fair value for grants (in dollars per share)															$ 25.31	$ 26.05
Term of award															4 years	5 years
Expected lives															4 years 18 days	4 years 4 months 6 days
Range of risk free interest rates used, minimum (as a percent)										1.28%
Range of risk free interest rates used, maximum (as a percent)										1.47%
Dividend yield (as a percent)										0.00%
Range of expected volatility rates used, minimum (as a percent)										46.60%
Range of expected volatility rates used, maximum (as a percent)										50.53%
Granted, issued or earned, Awards issued or earned (in shares)																									2,628	5,256
Total grant date fair values																									$ 150,000	$ 320,000
Average share price (in dollars per share)																									$ 58.18	$ 62.09
Vested and settled or exercised, Vested and settled (in shares)																											62,304	100,000
Vested and settled or exercised, Vested and settled (in dollars per share)																											$ 67.10	$ 67.10
Number of shares withheld for the federal tax obligations	0																																			68,086
Stock options exercised (in shares)									26,450	99,419																			0	20,000
Stock issued under employee stock purchase plan (in shares)																															13,848
Stock issued under employee stock purchase plan (in shares)																															690,000
SHARE-BASED PAYMENT EXPENSE
Share-based payment expense					1,983,000	3,464,000	3,352,000	6,883,000			910,000	613,000	1,614,000	1,202,000			219,000	150,000	466,000	287,000	687,000	2,543,000	1,105,000	5,236,000								167,000	158,000	167,000	158,000
Less income tax benefits	(246,000)	(686,000)	(373,000)	(1,411,000)
Share-based payment expense, net of income tax benefits	$ 1,737,000	$ 2,778,000	$ 2,979,000	$ 5,472,000
Earnings per share impact of share-based payment expense:
Basic (in dollars per share)	$ 0.06	$ 0.09	$ 0.10	$ 0.17
Diluted (in dollars per share)	$ 0.06	$ 0.09	$ 0.10	$ 0.17