Leases (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2018
Lease Assets [Abstract]
Right-of-use assets		$ 64.9	$ 61.3
Finance lease ROU assets, Property, plant and equipment - net	[1]	8.8
Lease Liabilities [Abstract]
Operating lease liabilities, Other current liabilities		12.9
Operating lease liabilities, Other noncurrent liabilities		50.7
Finance lease liabilities, Long-term debt - current portion		0.3
Finance lease liabilities, Long-term debt		3.6
Accumulated amortization		1.4
Components of Lease Expense [Abstract]
Operating lease expense	[2]	5.2
Finance lease expense [Abstract]
Depreciation of ROU assets		0.1
Interest on lease liabilities		0.0
Total lease expense		5.3
Short-term lease expense		0.9
Cash paid for amounts included in measurement of lease liabilities [Abstract]
Operating cash flows for operating leases		3.7
Financing cash flows for finance leases		0.1
ROU assets obtained in exchange for lease liabilities [Abstract]
Operating leases		0.3
Finance leases		$ 0.0
Weighted-average remaining lease term [Abstract]
Operating leases		8 years 10 months 24 days
Finance leases		9 years 8 months 12 days
Weighted-average discount rate [Abstract]
Operating leases		3.40%
Finance leases		2.00%
Maturity of Operating Lease Liabilities [Abstract]
Remainder of fiscal 2020		$ 11.4
2021		13.4
2022		9.9
2023		8.0
2024		5.5
2025 and beyond		24.8
Total lease payments		73.0
Less: Interest		(9.4)
Present value of lease liabilities		63.6
Maturities of Finance Lease Liabilities [Abstract]
Remainder of fiscal 2020		0.4
2021		0.5
2022		0.5
2023		0.5
2024		0.5
2025 and beyond		2.5
Total lease payments		4.9
Less: Interest		(1.0)
Present value of lease liabilities		$ 3.9
Future minimum rental commitments under non-cancelable operating leases [Abstract]
2020			14.2
2021			12.4
2022			9.1
2023			7.1
2024			4.7
2025 and beyond			22.9
Total future minimum rental commitments			70.4
Rental expense			$ 19.3	$ 18.5
Minimum [Member]
Significant Accounting Policy [Abstract]
Remaining lease term		1 year
Maximum [Member]
Significant Accounting Policy [Abstract]
Remaining lease term		11 years
CIS [Member]
Maturity of Operating Lease Liabilities [Abstract]
Total lease payments		$ 7.0
Operating lease term		15 years

[1] Finance lease ROU assets are recorded net of accumulated amortization of $1.4 million as of June 30, 2019.

[2] For the three months ended June 30, 2019, operating lease expense included $0.9 million of short-term lease expense. Variable lease expense was not significant.