Pensions (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost	[1]	$ 0.7	$ 0.8	$ 1.4	$ 1.6
Pension [Member]
Components of net periodic benefit cost [Abstract]
Service cost		0.1	0.2	0.2	0.3
Interest cost		2.4	2.4	4.8	4.9
Expected return on plan assets		(3.1)	(3.0)	(6.1)	(6.0)
Amortization of unrecognized net loss		1.4	1.4	2.8	2.8
Net periodic benefit cost		$ 0.8	$ 1.0	1.7	2.0
Pension [Member] | United States [Member]
Defined benefit plan, plan assets [Abstract]
Employer contributions				$ 3.7	$ 4.5

[1] Represents net periodic benefit cost, exclusive of service cost, for the Company's pension and postretirement plans.