Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Income Taxes [Line Items]
Unrecognized tax benefits that if realized would impact effective tax rate	$ 12.1	$ 64.9
Net interest and penalties recognized related to uncertain tax positions	(8.9)	5.0	$ 6.0
Accrued interest related to unrecognized tax benefits	7.0	$ 16.7
Settlement of prior year refund claim, income tax benefit recognized	70.0
Accrued interest and penalties	10.0
Unrecognized tax benefits estimated that may be realized in next 12 months	8.1
Foreign Tax Authority | Canada
Income Taxes [Line Items]
Net operating loss carryforwards	361.6
Foreign Tax Authority | Luxembourg
Income Taxes [Line Items]
Net operating loss carryforwards	504.3
Foreign Tax Authority | Other Foreign
Income Taxes [Line Items]
Net operating loss carryforwards	24.6
Foreign Tax Authority | SPAIN
Income Taxes [Line Items]
Net operating loss carryforwards	96.1
Foreign Tax Authority | UNITED KINGDOM
Income Taxes [Line Items]
Net operating loss carryforwards	95.1
State and Local Jurisdiction
Income Taxes [Line Items]
Net operating loss carryforwards	1,203.9
Domestic Tax Authority | United States
Income Taxes [Line Items]
Net operating loss carryforwards	1,330.6
Credit carryforward	$ 64.9