Income Taxes, Tax Cuts and Jobs Act (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Taxes [Abstract]
Provisional income tax expense (benefit) related to US Tax Reform		$ 38.0
Deferred tax assets - change in amount	$ (9.3)	(19.0)
Transition tax charge	(0.1)	$ 19.0
Income tax expense (benefit) related to US Tax Reform	(7.7)
Transition tax liability	18.9
Domestic Tax Jurisdiction [Member]
Income Taxes [Abstract]
Income tax expense (benefit) related to US Tax Reform	$ 1.7