CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales		$ 5,274.2	$ 5,349.5	$ 3,980.8
Cost of sales	[1]	2,032.1	2,418.2	1,560.1
Gross profit		3,242.1	2,931.3	2,420.7
Research and development	[1]	877.8	826.3	529.3
Selling, general and administrative	[1]	676.6	682.9	452.1
Amortization of acquired intangible assets		993.9	674.1	485.5
Special charges and other, net	[1]	46.7	33.7	17.5
Operating expenses		2,595.0	2,217.0	1,484.4
Operating income		647.1	714.3	936.3
Losses on equity method investments		0.0	(0.2)	(0.2)
Other income (expense):
Interest income		2.8	8.1	22.0
Interest expense		(497.3)	(502.9)	(199.0)
Loss on settlement of debt		(5.4)	(12.6)	(16.0)
Other income (loss), net		3.2	(2.2)	(5.8)
Income before income taxes		150.4	204.5	737.3
Income tax (benefit) provision		(420.2)	(151.4)	481.9
Net income		$ 570.6	$ 355.9	$ 255.4
Basic net income per common share (in dollars per share)		$ 2.39	$ 1.51	$ 1.10
Diluted net income per common share (in dollars per share)		2.23	1.42	1.03
Dividends declared per common share (in dollars per share)		$ 1.465	$ 1.457	$ 1.449
Basic common shares outstanding (in shares)		238.9	236.2	232.9
Diluted common shares outstanding (in shares)		256.2	249.9	248.9

[1] Year ended March 31,(1) Includes share-based compensation expense as follows: Cost of sales$20.9 $14.9 $13.8Research and development$82.9 $72.0 $42.5Selling, general and administrative$66.4 $62.3 $36.9Special charges and other, net$— $17.2 $—