Financial Instruments - Schedule of Pre-Tax Effect of Derivatives on Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Total direct operating expense on consolidated statements of operations	$ 2,210.0	$ 1,886.7	$ 2,207.9
Total interest expense on consolidated statements of operations	242.5	222.5	162.6
Forward exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in accumulated other comprehensive income (loss)	3.4	(5.8)	1.7
Gain (loss) reclassified from accumulated other comprehensive (income) loss	(1.2)	(0.3)	(0.3)
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in accumulated other comprehensive income (loss)	(0.6)	36.3	81.1
Gain (loss) reclassified from accumulated other comprehensive (income) loss	28.6	41.8	1.4
Gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense	$ 4.3	$ (7.2)	$ (11.8)