Business Acquisitions - Pro Forma (Details) - Microsemi Corporation - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Net sales	$ 1,374.7	$ 1,462.9	$ 4,234.0	$ 4,380.5
Net income (loss)	$ 102.4	$ (438.8)	$ 420.5	$ (742.5)
Basic net income (loss) per common share (in usd per share)	$ 0.43	$ (1.87)	$ 1.78	$ (3.20)
Diluted net income (loss) per common share (in usd per share)	$ 0.42	$ (1.87)	$ 1.69	$ (3.20)