Business, Basis of Presentation and Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Adoption of new accounting pronouncement
Trade accounts and notes receivable	$ 445,771	$ 346,450
Other accrued expenses and current liabilities	79,848	45,146
Other accrued expenses and liabilities	5,434	3,601	$ (2,308)
Debt issuance costs	7,933	3,283	3,844
ASU 2014-09
Adoption of new accounting pronouncement
Trade accounts and notes receivable	(3,600)
Other accrued expenses and current liabilities	$ (3,600)
ASU 2016-15
Adoption of new accounting pronouncement
Other accrued expenses and liabilities		2,600	1,200
Debt issuance costs		$ 2,600	$ 1,200