Other Financial Statement Details - Property, Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 2,979.9		$ 2,979.9		$ 2,945.7
Less accumulated depreciation and amortization	2,070.2		2,070.2		1,949.0
Total property, plant and equipment, net	909.7		909.7		996.7
Depreciation	41.4	$ 47.0	127.1	$ 132.2
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	657.6		657.6		647.6
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	2,130.2		2,130.2		2,095.5
Projects in process
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 108.7		$ 108.7		$ 119.2