Stock-based compensation plan - Summary of Unvested SARs Activity (Details) - SARs $ / shares in Units, $ in Thousands	6 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares
Number of SARs
Unvested as of beginning of period (in shares) | shares	40,567,917
Exercised (in shares) | shares	(1,392,917)
Forfeited (in shares) | shares	(300,000)
Unvested as of end of period (in shares) | shares	38,875,000
Vested and expected to vest (in shares) | shares	37,762,500
Vested (in shares) | shares	16,625,000
Weighted- Average Award Price in U.S. Cents
Outstanding as of beginning of period (in dollars per share) | $ / shares	$ 0.36
Exercised (in dollars per share) | $ / shares	0.21
Forfeited (in dollars per share) | $ / shares	0.46
Outstanding as of end of period (in dollars per share) | $ / shares	0.37
Vested and expected to vest (in dollars per share) | $ / shares	0.37
Vested (in dollars per share) | $ / shares	$ 0.28
Weighted average remaining contractual term, outstanding	2 years 10 months 13 days
Weighted average remaining contractual term, vested and expected to vest	2 years 21 days
Weighted average remaining contractual term, vested	1 year 5 months 23 days
Aggregate intrinsic value, vested and expected to vest | $	$ 5,857
Aggregate intrinsic value, vested | $	$ 3,799