Net Sales (Details) $ in Millions	3 Months Ended
	Jun. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Revenues	$ 1,212.5
Distributors
Disaggregation of Revenue [Line Items]
Revenues	645.7
Direct Customers
Disaggregation of Revenue [Line Items]
Revenues	540.1
Licensees
Disaggregation of Revenue [Line Items]
Revenues	26.7
Microcontrollers
Disaggregation of Revenue [Line Items]
Revenues	722.5
Analog, Interface, Mixed Signal and Timing Products
Disaggregation of Revenue [Line Items]
Revenues	331.9
Memory Products
Disaggregation of Revenue [Line Items]
Revenues	50.0
Field-programmable Gate Array Products
Disaggregation of Revenue [Line Items]
Revenues	37.8
Technology licensing
Disaggregation of Revenue [Line Items]
Revenues	26.7
Multi-Market and Other
Disaggregation of Revenue [Line Items]
Revenues	$ 43.6