Special (Income) Charges and Other, Net - Income Statement Disclosure (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Other Nonrecurring (Income) Expense [Abstract]
Employee separation costs		$ 3.3	$ 0.1	$ 60.5	$ 1.5
Gain on sale of assets		0.0	0.0	0.0	(4.4)
Impairment charges		0.2	0.0	3.7	0.0
Contract exit costs		0.1	(0.1)	(2.9)	0.6
Other		0.1	0.1	0.7	0.0
Legal settlement		(5.0)	0.0	(5.0)	0.0
Non-restructuring contract exit costs and other		0.0	0.1	0.0	19.6
Total	[1]	$ (1.3)	$ 0.2	$ 57.0	$ 17.3

[1] Includes share-based compensation expense as follows: Cost of sales$3.4 $3.5 $10.9 $10.6Research and development$19.4 $10.9 $53.2 $31.8Selling, general and administrative$16.6 $9.6 $46.1 $27.6Special (income) charges and other, net$0.2 $— $17.3 $—