Leasing - Lease term and discount rate (Details)	Mar. 31, 2020	Mar. 31, 2019
Weighted-average remaining lease term (years)
Operating leases	5 years 6 months	5 years
Finance leases	4 years 7 months 6 days	4 years
Weighted-average discount rate
Operating leases	4.80%	4.95%
Finance leases	4.06%	4.33%