Leases (Details 4)	Jul. 31, 2020	Apr. 30, 2020
Leases [Abstract]
Operating leases, Weighted average remaining lease term	4 years 7 months 6 days	4 years 8 months 12 days
Finance leases, Weighted average remaining lease term	3 years 2 months 12 days	3 years 4 months 24 days
Operating leases, Weighted average discount rate	3.10%	3.10%
Finance leases, Weighted average discount rate	2.90%	2.90%