Business Acquisitions - Pro Forma, Microsemi (Details) - Microsemi Corporation - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Business Acquisition [Line Items]
Net sales	$ 5,563.7	$ 5,875.0
Net income (loss)	$ 542.0	$ (762.3)
Basic net income (loss) per common share (in usd per share)	$ 2.29	$ (3.27)
Diluted net income (loss) per common share (in usd per share)	$ 2.17	$ (3.27)