Leases - Supplemental balance sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 16,637	$ 0
Property, plant and equipment	695
Total right-of-use assets	17,332
Lease liabilities	201
Non-current lease liabilities	511
Total lease liabilities	19,124
Lease liabilities [Member]
Lessee, Lease, Description [Line Items]
Lease liabilities	3,352
Non-current lease liabilities [Member]
Lessee, Lease, Description [Line Items]
Non-current lease liabilities	$ 15,060