Summary of significant accounting policies - Narrative (Details)	4 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) shares	Mar. 31, 2022 ZAR (R)	Mar. 31, 2022 USD ($) shares	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($) shares	Mar. 31, 2022 ZAR (R) shares	Dec. 03, 2021 ZAR (R)	May 23, 2017 ZAR (R)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred commissions	$ 4,135,000		$ 4,135,000	$ 3,687,000
Restricted cash	$ 981,000		981,000	854,000
Write-down of inventory			790,000	660,000	$ 339,000
Goodwill impairments			0	0
Impairment of long-lived assets (less than)			$ 47,000	$ 8,000	6,000
Treasury stock (in shares) | shares	53,816,750		53,816,750	53,800,000		53,816,750
Shares repurchased	$ 3,100,000	R 44,700,000	$ 3,000,000	$ 0	$ 9,800,000
Shares repurchased (in shares) | shares			6,020,085	0	16,856,001
Shares repurchased and delisted (in shares) | shares					3,039,251
Expected forfeiture rates			5.00%
Advertising costs			$ 4,200,000	$ 2,300,000	$ 2,000,000.0
May 2017 Share Repurchase Program
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Approved share repurchase program amount	18,600,000		18,600,000					R 270,000,000
Maximum value of shares that may still be repurchased	11,000,000		11,000,000				R 160,000,000
December 2021 Share Repurchase Program Modification
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Approved share repurchase program amount	27,400,000		27,400,000				R 396,500,000
Maximum value of shares that may still be repurchased	8,000,000.0		8,000,000.0			R 115,300,000
Subsidiary
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares repurchased (in shares) | shares					13,816,750
Asset Held in Trust
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 700,000		$ 700,000	$ 500,000
Minimum | Patents and trademarks
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			3 years
Minimum | Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			2 years
Minimum | Internal-use software, technology and other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			1 year
Maximum | Patents and trademarks
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			20 years
Maximum | Customer relationships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			15 years
Maximum | Internal-use software, technology and other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life of intangible assets			18 years
Subscription | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract service period			1 month
Subscription | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract service period			60 months