Schedule II - Valuation and Qualifying Accounts - Schedule II (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Valuation allowance for trade and notes receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 4.4	$ 5.4	$ 4.0
Charged to Costs and Expenses	(1.3)	0.2	(0.2)
Acquired Obligations	0.5	0.6	2.0
Charged to Other Accounts	0.0	0.0	0.0
Deductions	(0.5)	(1.8)	(0.4)
Balance at End of Year	3.1	4.4	5.4
Valuation allowance for income taxes
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	23.0	21.8	24.1
Charged to Costs and Expenses	13.3	2.1	0.9
Acquired Obligations	0.0	4.0	0.2
Charged to Other Accounts	2.0	0.0	0.0
Deductions	(5.9)	(4.9)	(3.4)
Balance at End of Year	$ 32.4	$ 23.0	$ 21.8