Financial Instruments - Narrative (Details) - USD ($) $ in Millions	1 Months Ended		2 Months Ended	12 Months Ended
	Dec. 31, 2024	May 31, 2022	May 31, 2022	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Derivative [Line Items]
Reduction to asset value		$ 188.7		$ 0.0	$ 0.0	$ (188.7)
Unrealized gain recorded in accumulated other comprehensive income (loss)				1,016.6	1,150.2	778.9	$ 259.5
Net cash provided by (used in) operating activities				(106.8)	488.9	346.1
Net cash provided by (used in) financing activities				(84.5)	74.9	$ 394.5
Foreign currency cash flow hedge gains estimated to be reclassified into earnings during next 12 months				1.1
Interest rate swap cash flow hedge gain estimated to be reclassified into earnings during next 12 months				$ 26.4
Designated as Hedging Instrument
Derivative [Line Items]
Interest rate swaps (see Note 19)					2.8
Interest rate swaps
Derivative [Line Items]
Proceeds from termination of interest rate swaps		56.4
Reduction of financing component		131.3	$ (3.2)
Net cash provided by (used in) operating activities		188.7
Net cash provided by (used in) financing activities		134.5
Interest rate swaps | Accumulated Gain (Loss), Net, Cash Flow Hedge Discontinued, Including Noncontrolling Interest
Derivative [Line Items]
Unrealized gain recorded in accumulated other comprehensive income (loss)		180.4	180.4
Interest rate swaps | Designated as Hedging Instrument
Derivative [Line Items]
Unrealized gain on derivatives	$ 9.4
Interest rate swaps (see Note 19)		$ 6.8	$ 6.8		$ 0.0