Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Mar. 31, 2018 USD ($) segment day	Mar. 31, 2017 USD ($)
Accounting Policies [Abstract]
Deferred revenue on shipments to distributors	$ 479.6	$ 418.0
Deferred cost of sales on shipments to distributors	145.8	125.2
Deferred income on shipments to distributors	$ 333.8	292.8
Property, Plant and Equipment [Line Items]
Effective income tax rate	31.50%
Amount of distributor advances, included in deferred income on shipments to distributors in consolidated balance sheets	$ 203.9	$ 203.9
Number of reporting units	2
Number of days requiring distributor to settle receivable balances (in days) | day	30
Number of operating segments | segment	2
Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	1 year
Minimum | Building and Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	10 years
Minimum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	3 years
Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Maximum | Building and Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	40 years
Maximum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	7 years