CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 170.2	$ 166.4	$ 93.2
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	20.9	14.9	13.8
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	82.9	72.0	42.5
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	66.4	62.3	36.9
Special charges and other, net
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 0.0	$ 17.2	$ 0.0