Income Taxes - Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of period	$ 18.3	$ 15.6
Additions based on tax positions related to the current year	1.5	7.7
Additions for tax positions of prior years	0.0	4.7
Reductions for tax positions of prior years	0.0	0.0
Settlements	(1.4)	(2.3)
Reductions due to lapse of applicable statute of limitations	(4.5)	(7.1)
Cumulative translation adjustment, decrease	(0.3)	(0.3)
Balance at end of period	$ 13.6	$ 18.3