Significant Accounting Policies, Short-term Investments, Property, Plant and Equipment and Assets Held for Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Short-Term Investments [Abstract]
Short-term investments	$ 3.2	$ 4.3
Property, Plant and Equipment [Abstract]
Capital expenditures accrued	8.7	17.9	$ 15.8
Goodwill [Abstract]
Goodwill impairment charge	0.5
Impairment of Long-lived Assets [Abstract]
Impairment of long-lived assets	8.1
Assets Held For Sale [Abstract]
Carrying value of assets held-for-sale	0.6	$ 1.1
VTS [Member]
Goodwill [Abstract]
Goodwill impairment charge	$ 0.5