Leases - Supplemental cash flow information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 32,208	$ 30,976
Operating cash flows from finance leases	8,673	10,089
Financing cash flows from finance leases	22,662	17,971
Right-of-use assets obtained in exchange for lease obligations - Operating leases	27,918	32,042
Right-of-use assets obtained in exchange for lease obligations - Finance leases	$ 22,408	$ 39,379