Income Taxes - Income Tax Provision (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Current:
United States	$ 55.7	$ 29.9	$ 18.9
Non-United States	21.6	23.1	16.0
State and local	8.0	4.1	2.5
Total current	85.3	57.1	37.4
Deferred:
United States	(23.0)	(71.5)	(19.1)
Non-United States	(5.2)	(3.1)	(0.9)
State and local	(3.7)	(2.0)	(1.8)
Total deferred	(31.9)	(76.6)	(21.8)
Provision (benefit) for income taxes	$ 53.4	$ (19.5)	$ 15.6