Quarterly Financial Information, Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 193,759	$ 227,459	$ 195,045	$ 242,667	$ 217,611	$ 242,447	$ 214,246	$ 228,888	$ 858,930	$ 903,192	$ 816,687
Gross profit	45,705	53,866	41,886	63,327	54,854	62,448	53,505	59,304	204,784	230,111	205,696
Net income	$ 11,584	$ 18,251	$ 10,023	$ 21,063	$ 16,076	$ 23,547	$ 17,243	$ 19,924	$ 60,921	$ 76,790	$ 64,943
Basic earnings per common share (usd per share)	$ 0.45	$ 0.70	$ 0.39	$ 0.81	$ 0.62	$ 0.91	$ 0.67	$ 0.77	$ 2.35	$ 2.98	$ 2.53
Diluted earnings per common share (usd per share)	$ 0.44	$ 0.70	$ 0.38	$ 0.81	$ 0.62	$ 0.91	$ 0.67	$ 0.77	$ 2.33	$ 2.96	$ 2.52