Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Income Statement [Abstract]
Net sales	$ 1,030,248	$ 947,045	$ 825,465
Cost of sales and distribution	805,612	747,351	672,933
Gross Profit	224,636	199,694	152,532
Selling and marketing expenses	70,979	66,489	64,304
General and administrative expenses	45,419	40,045	33,773
Restructuring charges, net	0	0	(240)
Operating Income	108,238	93,160	54,695
Interest expense	885	378	515
Other income	(1,572)	996	(207)
Income Before Income Taxes	108,925	91,786	54,387
Income tax expense	37,726	33,063	18,888
Net Income	$ 71,199	$ 58,723	$ 35,499
Earnings per share
Basic (usd per share)	$ 4.38	$ 3.61	$ 2.25
Diluted (usd per share)	$ 4.34	$ 3.57	$ 2.21