Income taxes - Schedule of Components of Income Before Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Domestic (South Africa)	$ 12,254	$ 14,443	$ 30,464
Foreign	1,111	2,786	(9,648)
Income before income tax expense	$ 13,365	$ 17,229	$ 20,816