CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 36.2	$ 311.1	$ 233.4	$ 470.7
Defined benefit plans:
Actuarial (losses) gains related to defined benefit pension plans, net of tax effect	(3.5)	(1.6)	(6.9)	0.1
Reclassification of realized transactions, net of tax effect	0.3	0.2	0.9	0.6
Change in net foreign currency translation adjustment	1.8	1.7	5.3	(0.7)
Other comprehensive (loss) income, net of tax effect	(1.4)	0.3	(0.7)	0.0
Comprehensive income	$ 34.8	$ 311.4	$ 232.7	$ 470.7