Share-Based Compensation (Narrative) (Details) shares in Millions, $ in Millions	9 Months Ended
	Dec. 31, 2022 USD ($) plan shares	Dec. 31, 2021 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of plans | plan	2
Share-based compensation expense from acceleration, modification and subsequent remeasurement of awards | $		$ 3.0
Unrecognized compensation cost | $	$ 106.2
Unrecognized compensation expense, period for recognition	2 years 7 months 28 days
Myovant 2016 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares reserved for grant (in shares) | shares	2.7
2020 Inducement Equity Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares reserved for grant (in shares) | shares	0.2