Special Charges and Other, Net - Special Charges (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring
Employee separation costs		$ 0.6	$ 12.1	$ 7.3	$ 57.2
Impairment charges		0.0	1.5	0.5	3.5
Contract exit costs		0.5	4.0	0.5	(3.0)
Other		0.3	0.6	1.2	0.6
Legal contingencies		2.2	0.0	2.2	0.0
Total	[1]	$ 3.6	$ 18.2	$ 11.7	$ 58.3

[1] Three Months Ended September 30, Six Months EndedSeptember 30,(1) Includes share-based compensation expense as follows:2019 2018 2019 2018Cost of sales$5.2 $3.9 $10.1 $7.5Research and development$22.3 $19.7 $41.8 $33.8Selling, general and administrative$17.8 $17.8 $34.1 $29.5Special charges and other, net$— $1.2 $— $17.1