Leases - Supplemental cash flow information (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2021	Jul. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 11,189	$ 10,648
Operating cash flows from finance leases	2,301	3,062
Financing cash flows from finance leases	7,397	7,521
Right-of-use assets obtained in exchange for lease obligations
Operating leases	24,210	6,843
Finance leases	$ 4,076	$ 3,935