Capital Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023	May 13, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued (in shares)	288,700,000	253,400,000
Common shares exceeds price per share (in dollars per share)	$ 16.05
Tax deficiencies associated with equity awards	$ (2.4)	$ (7.4)	$ 8.7
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercises in period, intrinsic value	0.2	0.2	1.1
Restricted Stock and Restricted Share Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, vested in period, fair value	$ 37.9	$ 39.6	$ 29.1
Equity instruments other than options, shares withheld for tax purposes upon vesting of restricted share units (in shares)	3,300,000	3,000,000.0	1,500,000
Share-Based Payment Arrangement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, grants in period, total fair value	$ 2.3	$ 2.3	$ 2.3
Shares issued in period, net of shares for tax withholdings (in shares)	300,000	200,000	300,000
Minimum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Expiration period	7 years
Minimum | Restricted Stock and Restricted Share Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Maximum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
Expiration period	10 years
Cancellations in period, funding of tax withholding obligations (in shares)	100,000	100,000	100,000
Maximum | Restricted Stock and Restricted Share Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
SEAC Sponsor Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued (in shares)				2,200,000
Sponsor Option Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)				$ 0.0001