Leases - Future minimum lease payments under non-cancellable leases (Details) - USD ($) $ in Thousands	Jul. 31, 2021	Apr. 30, 2021
Finance
2022 (remaining nine months)	$ 33,640
2023	36,159
2024	26,971
2025	16,060
2026	8,415
Thereafter	3,792
Total lease payments	125,037
Less imputed interest	12,131
Total	112,906	$ 117,948
Operating
2022 (remaining nine months)	32,773
2023	38,059
2024	32,185
2025	22,412
2026	12,584
Thereafter	19,161
Total lease payments	157,174
Less imputed interest	18,541
Total	$ 138,633