Quarterly Financial Information, Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 29, 2016	Feb. 28, 2015	Feb. 28, 2014
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 217,611	$ 242,447	$ 214,246	$ 228,888	$ 182,312	$ 224,833	$ 193,416	$ 216,126	$ 903,192	$ 816,687	$ 751,723
Gross profit	54,854	62,448	53,505	59,304	47,432	60,775	42,100	55,389	230,111	205,696	205,705
Net income	$ 16,076	$ 23,547	$ 17,243	$ 19,924	$ 16,283	$ 19,965	$ 13,769	$ 14,925	$ 76,790	$ 64,943	$ 59,597
Basic earnings per common share (usd per share)	$ 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)	$ 0.62	$ 0.91	$ 0.67	$ 0.77	$ 0.63	$ 0.77	$ 0.53	$ 0.58	$ 2.96	$ 2.52	$ 2.32