Leases - Future minimum lease payments under non-cancellable leases (Details) $ in Thousands	Jul. 31, 2019 USD ($)
Finance lease
2020 (remaining nine months)	$ 31,712
2021	38,061
2022	31,246
2023	22,544
2024	13,703
Thereafter	4,561
Total lease payments	141,827
Less imputed interest	27,784
Total	114,043
Operating lease
2020 (remaining nine months)	29,362
2021	31,829
2022	23,263
2023	16,999
2024	12,400
Thereafter	18,707
Total lease payments	132,560
Less imputed interest	16,554
Total	$ 116,006