Geographic and Segment Information - Net Sales and Gross Profit (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Segment reporting information [Line Items]
Net Sales	$ 5,438.4	$ 5,274.2	$ 5,349.5
Gross Profit	3,378.8	3,242.1	2,931.3
Semiconductor products
Segment reporting information [Line Items]
Net Sales	5,335.5	5,177.3	5,217.1
Gross Profit	3,275.9	3,145.2	2,798.9
Technology licensing
Segment reporting information [Line Items]
Net Sales	102.9	96.9	132.4
Gross Profit	$ 102.9	$ 96.9	$ 132.4