Quarterly Financial Information, Unaudited (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2013
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 182,312	$ 224,833	$ 193,416	$ 216,126	$ 181,011	$ 197,755	$ 189,782	$ 183,175	$ 816,687	$ 751,723	$ 570,594
Gross profit	47,432	60,775	42,100	55,389	45,724	53,361	55,905	50,715	205,696	205,705	164,173
Net income	$ 16,283	$ 19,965	$ 13,769	$ 14,925	$ 10,242	$ 18,445	$ 16,363	$ 14,547	$ 64,943	$ 59,597	$ 60,456
Basic earnings per common share (usd per share)	$ 0.63	$ 0.78	$ 0.54	$ 0.58	$ 0.40	$ 0.72	$ 0.64	$ 0.57	$ 2.53	$ 2.34	$ 2.39
Diluted earnings per common share (usd per share)	$ 0.63	$ 0.77	$ 0.53	$ 0.58	$ 0.40	$ 0.72	$ 0.64	$ 0.57	$ 2.52	$ 2.32	$ 2.37