Segment information - Reconciliation of Segment Results to Income Before Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	$ 11,085	$ 12,049	$ 22,552	$ 22,469
Stock-based compensation costs	(300)	(300)	(700)	(600)
Net interest expense	(141)	(70)	(219)	(140)
Income before income tax expense	3,788	4,426	7,911	6,940
North America | Employee Severance
Segment Reporting Information [Line Items]
Restructuring costs		100		100
CSO
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	(2,457)	(1,674)	(5,044)	(3,537)
CSO | Employee Severance
Segment Reporting Information [Line Items]
Restructuring costs				600
Africa
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	8,874	7,249	17,778	14,494
Africa | Employee Severance
Segment Reporting Information [Line Items]
Restructuring costs				200
Operating Segments
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	11,085	12,049	22,552	22,469
Corporate and Eliminations
Segment Reporting Information [Line Items]
Corporate and consolidation entries	(2,474)	(2,507)	(4,850)	(4,837)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Operating lease costs	(373)	(399)	(780)	(791)
Product development costs	(335)	(271)	(698)	(514)
Depreciation and amortization	(3,668)	(3,836)	(7,347)	(7,464)
Impairment of long-lived assets	(28)	(1)	(28)	(1)
Stock-based compensation costs	(330)	(301)	(694)	(594)
Increase in restructuring costs	(51)	(153)	(52)	(997)
Net (loss)/profit on sale of property and equipment	43	(7)	43	(8)
Net foreign exchange (losses)/gains	60	(78)	(16)	(183)
Net interest expense	$ (141)	$ (70)	$ (219)	$ (140)