CONDENSED CONSOLIDATED STATEMENTS OF INCOME (PARENTHETICAL) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 43.5	$ 39.6	$ 129.5	$ 127.5
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	5.7	3.4	15.8	10.9
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	21.2	19.4	63.0	53.2
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	16.6	16.6	50.7	46.1
Special charges (income) and other, net
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 0.0	$ 0.2	$ 0.0	$ 17.3