Segment information - Schedule of Long-Lived Assets by Geographical Location (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Long-lived assets	$ 82,950	$ 92,944
South Africa
Segment Reporting Information [Line Items]
Long-lived assets	56,250	58,704
America
Segment Reporting Information [Line Items]
Long-lived assets	10,027	10,370
Europe
Segment Reporting Information [Line Items]
Long-lived assets	9,697	16,775
Middle East and Australia
Segment Reporting Information [Line Items]
Long-lived assets	5,559	5,500
Brazil
Segment Reporting Information [Line Items]
Long-lived assets	$ 1,417	$ 1,595