Pension and Employee Benefit Plans, Defined Benefit Employee Benefit Plans (Details) $ in Millions		12 Months Ended
		Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($) Participant
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	[1]	$ 3.3	$ 2.9	$ 44.6
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		16.0	9.5
Net periodic benefit cost		4.1	3.7	45.4
Pension Plans [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		13.4	8.1	$ 6.7
Voluntary Lump Sum Payout Program [Abstract]
Number of participants accepted lump-sum payout program | Participant				2,000
Amount paid for settlement lump-sum payout program				$ 65.3
Pension Plans [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		2.6	1.4	1.2
Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 0.2	$ 0.3	$ 0.3

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