Segments - Net Sales, Adjusted EBITDA and Certain Other Measures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Segment information
Net sales	$ 780,149	$ 723,902	$ 833,837	$ 778,144	$ 653,800	$ 585,508	$ 648,004	$ 642,157	$ 3,116,032	$ 2,511,469	$ 2,319,146
Gross Profit	256,927	$ 234,226	$ 268,150	$ 244,816	205,792	$ 195,420	$ 212,260	$ 205,104	1,004,119	818,576	758,571
Depreciation and Amortization									117,459	65,530	69,240
Adjusted EBITDA									295,669	199,258	188,229
Total assets	2,149,554				1,454,511				2,149,554	1,454,511	1,393,265
Geographic divisions
Segment information
Net sales									3,090,314	2,487,557	2,298,871
Gross Profit									994,981	809,884	750,564
Depreciation and Amortization									114,558	64,491	68,001
Adjusted EBITDA									293,190	196,903	186,155
Total assets	2,125,518				1,434,371				2,125,518	1,434,371	1,376,655
Other.
Segment information
Net sales									25,718	23,912	20,275
Gross Profit									9,138	8,692	8,007
Depreciation and Amortization									220	242	310
Adjusted EBITDA									2,479	2,355	2,074
Total assets	16,897				12,854				16,897	12,854	11,916
Corporate
Segment information
Depreciation and Amortization									2,681	797	929
Total assets	$ 7,139				$ 7,286				$ 7,139	$ 7,286	$ 4,694