Pensions (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Mar. 31, 2026	Sep. 30, 2025	Sep. 30, 2024
Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	[1]	$ 1.2	$ 1.1		$ 2.5	$ 2.3
Pension
Net Periodic Benefit Cost [Abstract]
Service cost		0.1	0.1		0.1	0.1
Interest cost		2.2	2.2		4.6	4.5
Expected return on plan assets		(2.1)	(2.1)		(4.3)	(4.3)
Amortization of unrecognized net loss		1.2	1.1		2.4	2.3
Net periodic benefit cost		$ 1.4	$ 1.3		2.8	$ 2.6
Pension | UNITED STATES
Defined Benefit Plan, Additional Information [Abstract]
Contribution U.S. pension plan					$ 0.0
Pension | UNITED STATES | Minimum
Termination of U.S. Pension Plans [Abstract]
Expected employer contribution during fiscal 2026				$ 20.0
Pension | UNITED STATES | Maximum
Termination of U.S. Pension Plans [Abstract]
Expected employer contribution during fiscal 2026				25.0
Pension | UNITED STATES | Termination plan | Minimum
Termination of U.S. Pension Plans [Abstract]
Non-cash pension settlement charges				(120.0)
Pension | UNITED STATES | Termination plan | Maximum
Termination of U.S. Pension Plans [Abstract]
Non-cash pension settlement charges				$ (125.0)

[1] Net periodic benefit cost for the Company’s pension and postretirement plans is exclusive of service cost.