Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,309.7	$ 1,322.6
Distributors
Disaggregation of Revenue [Line Items]
Total net sales	658.9	665.1
Direct customers
Disaggregation of Revenue [Line Items]
Total net sales	628.9	638.9
Licensees
Disaggregation of Revenue [Line Items]
Total net sales	21.9	18.6
Microcontrollers
Disaggregation of Revenue [Line Items]
Total net sales	716.4	708.3
Analog, interface, mixed signal and timing products
Disaggregation of Revenue [Line Items]
Total net sales	370.2	386.4
Field-programmable gate array products
Disaggregation of Revenue [Line Items]
Total net sales	86.8	91.0
Licensing, memory and other
Disaggregation of Revenue [Line Items]
Total net sales	$ 136.3	$ 136.9