Income Taxes, Income Tax Provision (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Federal [Abstract]
Current	$ (3.4)	$ (20.4)	$ 11.6
Deferred	(1.7)	(4.2)	23.3
State [Abstract]
Current	(0.1)	0.7	(0.3)
Deferred	(2.3)	1.9	2.0
Foreign [Abstract]
Current	14.9	19.0	16.1
Deferred	5.0	(2.1)	(13.2)
Total income tax provision (benefit)	$ 12.4	$ (5.1)	$ 39.5