Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,569.4	$ 1,309.7
Distributors
Disaggregation of Revenue [Line Items]
Total net sales	783.4	658.9
Direct customers
Disaggregation of Revenue [Line Items]
Total net sales	758.6	628.9
Licensees
Disaggregation of Revenue [Line Items]
Total net sales	27.4	21.9
Microcontrollers
Disaggregation of Revenue [Line Items]
Total net sales	902.5	716.4
Analog
Disaggregation of Revenue [Line Items]
Total net sales	432.1	370.2
Other
Disaggregation of Revenue [Line Items]
Total net sales	$ 234.8	$ 223.1