Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Income Statement [Abstract]
Net sales	$ 1,250,274	$ 1,030,248	$ 947,045
Cost of sales and distribution	994,871	805,612	747,351
Gross Profit	255,403	224,636	199,694
Selling and marketing expenses	77,843	70,979	66,489
General and administrative expenses	69,855	45,419	40,045
Operating Income	107,705	108,238	93,160
Interest expense (income), net	13,054	(521)	129
Other (income) expense	(109)	(166)	1,245
Income Before Income Taxes	94,760	108,925	91,786
Income tax expense	31,619	37,726	33,063
Net Income	$ 63,141	$ 71,199	$ 58,723
Earnings per share
Basic (usd per share)	$ 3.80	$ 4.38	$ 3.61
Diluted (usd per share)	$ 3.77	$ 4.34	$ 3.57