Other Financial Statement Details - Property, Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 2,994.6		$ 2,994.6		$ 2,966.1
Less accumulated depreciation and amortization	2,172.5		2,172.5		2,090.0
Total property, plant and equipment, net	822.1		822.1		876.1
Depreciation expense	39.0	$ 39.5	80.1	$ 85.7
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	83.4		83.4		83.4
Building and building improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	661.4		661.4		659.5
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	2,169.5		2,169.5		2,123.1
Projects in process
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 80.3		$ 80.3		$ 100.1