Accumulated Other Comprehensive Loss - Schedule of Changes in the Components of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Changes in the components of AOCI
Beginning balance	$ 6,513.6	$ 5,894.8	$ 5,337.1
Net other comprehensive income	0.6	16.5	5.6
Ending balance	6,657.8	6,513.6	5,894.8
Total
Changes in the components of AOCI
Beginning balance	(4.1)	(20.6)	(26.2)
Net other comprehensive income	0.6	16.5	5.6
Ending balance	(3.5)	(4.1)	(20.6)
Minimum Pension Liability
Changes in the components of AOCI
Beginning balance	11.0	(5.6)
Net other comprehensive income	0.6	16.6
Ending balance	11.6	11.0	(5.6)
Foreign Currency
Changes in the components of AOCI
Beginning balance	(15.1)	(15.0)
Net other comprehensive income	0.0	(0.1)
Ending balance	$ (15.1)	$ (15.1)	$ (15.0)