CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales		$ 1,212.5	$ 972.1
Cost of sales	[1]	570.5	387.7
Gross profit		642.0	584.4
Research and development	[1]	171.9	130.5
Selling, general and administrative	[1]	164.0	114.3
Amortization of acquired intangible assets		133.7	120.8
Special charges and other, net	[1]	40.1	(2.8)
Operating expenses		509.7	362.8
Operating income		132.3	221.6
Losses on equity method investment		(0.1)	(0.1)
Other income (expense):
Interest income		5.7	3.5
Interest expense		(90.4)	(49.5)
Loss on settlement of convertible debt		0.0	(13.8)
Other (loss) income, net		(9.8)	4.5
Income before income taxes		37.7	166.2
Income tax provision (benefit)		2.0	(4.4)
Net income		$ 35.7	$ 170.6
Basic net income attributable to Microchip Technology, per common share (in USD per share)		$ 0.15	$ 0.74
Diluted net income attributable to Microchip Technology, per common share (in USD per share)		0.14	0.70
Dividends declared per common share (in USD per share)		$ 0.3635	$ 0.3615
Basic common shares outstanding		235.2	229.4
Diluted common shares outstanding		252.2	242.9
Allocated Share-based Compensation Expense		$ 45.3	$ 22.4

[1] Includes share-based compensation expense as follows:Cost of sales 3.6 3.4 Research and development 14.1 10.3 Selling, general and administrative 11.7 8.7Special charges and other, net 15.9 0