Leases (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021
Lease Assets and Liabilities [Abstract]
Operating lease ROU assets		$ 51.0		$ 51.0		$ 54.1
Operating lease ROU assets, Statement of Financial Position [Extensible List]		Other noncurrent assets		Other noncurrent assets		Other noncurrent assets
Finance lease ROU assets	[1]	$ 8.0		$ 8.0		$ 8.3
Finance lease ROU assets, Statement of Financial Position [Extensible List]		Property, plant and equipment - net		Property, plant and equipment - net		Property, plant and equipment - net
Operating lease liabilities, current		$ 11.4		$ 11.4		$ 11.2
Operating lease liabilities, current, Statement of Financial Position [Extensible List]		Other current liabilities		Other current liabilities		Other current liabilities
Operating lease liabilities, noncurrent		$ 41.4		$ 41.4		$ 44.8
Operating lease liabilities, noncurrent, Statement of Financial Position [Extensible List]		Other noncurrent liabilities		Other noncurrent liabilities		Other noncurrent liabilities
Finance lease liabilities, current		$ 0.4		$ 0.4		$ 0.4
Finance lease liabilities, current, Statement of Financial Position [Extensible List]		Long-term debt - current portion		Long-term debt - current portion		Long-term debt - current portion
Finance lease liabilities, noncurrent		$ 3.0		$ 3.0		$ 3.2
Finance lease liabilities, noncurrent, Statement of Financial Position [Extensible List]		Long-term debt		Long-term debt		Long-term debt
Accumulated amortization		$ 2.6		$ 2.6		$ 2.4
Components of Lease Expense [Abstract]
Operating lease expense	[2]	4.8	$ 5.2	9.4	$ 10.1
Finance lease expense [Abstract]
Depreciation of ROU assets		0.2	0.1	0.3	0.2
Interest on lease liabilities		0.1	0.1	0.1	0.1
Total lease expense		5.1	5.4	9.8	10.4
Short-term lease expense		1.0	$ 0.9	1.8	$ 1.8
Assets Held for Sale [Member]
Lease Assets and Liabilities [Abstract]
Operating lease ROU assets		4.0		4.0		6.1
Liabilities Held for Sale [Member]
Lease Assets and Liabilities [Abstract]
Operating lease liabilities, current		$ 4.0		$ 4.0		$ 6.1

[1] Finance lease ROU assets were recorded net of accumulated amortization of $2.6 million and $2.4 million as of September 30, 2021 and March 31, 2021, respectively.

[2] For the three and six months ended September 30, 2021, operating lease expense included short-term lease expense of $1.0million and $1.8 million, respectively.  For the three and six months ended September 30, 2020, operating lease expense included short-term lease expense of $0.9 million and $1.8 million, respectively. Variable lease expense was not significant.