Segments - Net Sales, Adjusted EBITDA and Certain Other Measures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Segment information
Net sales	$ 833,837	$ 648,004	$ 1,611,981	$ 1,290,161
Gross Profit	268,150	212,260	512,966	417,364
Depreciation and Amortization	30,787	16,713	57,109	33,058
Adjusted EBITDA	87,145	54,245	162,417	106,994
Geographic divisions
Segment information
Net sales	827,198	641,918	1,598,748	1,278,285
Gross Profit	265,815	210,034	508,390	413,059
Depreciation and Amortization	30,062	16,466	55,916	32,492
Adjusted EBITDA	86,450	53,651	161,044	105,877
Other.
Segment information
Net sales	6,639	6,086	13,233	11,876
Gross Profit	2,335	2,226	4,576	4,305
Depreciation and Amortization	55	60	113	124
Adjusted EBITDA	695	594	1,373	1,117
Corporate
Segment information
Depreciation and Amortization	$ 670	$ 187	$ 1,080	$ 442