CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales		$ 1,337.8	$ 1,432.5	$ 2,660.4	$ 2,644.9
Cost of sales	[1]	510.3	743.2	1,017.7	1,313.6
Gross profit		827.5	689.3	1,642.7	1,331.3
Research and development	[1]	219.8	221.9	438.9	393.8
Selling, general and administrative	[1]	172.3	176.6	340.2	340.7
Amortization of acquired intangible assets		248.2	169.9	496.7	303.6
Special charges and other, net	[1]	3.6	18.2	11.7	58.3
Operating expenses		643.9	586.6	1,287.5	1,096.4
Operating income		183.6	102.7	355.2	234.9
Losses on equity method investments		0.0	(0.1)	0.0	(0.1)
Other income (expense):
Interest income		1.0	0.9	1.7	6.6
Interest expense		(129.6)	(138.6)	(262.2)	(229.0)
Loss on settlement of debt		(0.1)	(4.1)	(2.0)	(4.1)
Other (loss) income, net		(1.4)	(0.2)	1.3	(10.0)
Income (loss) before income taxes		53.5	(39.4)	94.0	(1.7)
Income tax benefit		(55.4)	(135.7)	(65.6)	(133.7)
Net Income		$ 108.9	$ 96.3	$ 159.6	$ 132.0
Basic net income per common share (in dollars per share)		$ 0.46	$ 0.41	$ 0.67	$ 0.56
Diluted net income per common share (in dollars per share)		0.43	0.38	0.63	0.52
Dividends declared per common share (in dollars per share)		$ 0.3660	$ 0.3640	$ 0.7315	$ 0.7275
Basic common shares outstanding (in shares)		238.4	235.8	238.1	235.5
Diluted common shares outstanding (in shares)		255.3	251.8	254.6	252.0

[1] Three Months Ended September 30, Six Months EndedSeptember 30,(1) Includes share-based compensation expense as follows:2019 2018 2019 2018Cost of sales$5.2 $3.9 $10.1 $7.5Research and development$22.3 $19.7 $41.8 $33.8Selling, general and administrative$17.8 $17.8 $34.1 $29.5Special charges and other, net$— $1.2 $— $17.1