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Business Acquisitions - Narrative, Microsemi (Details) - USD ($) $ in Millions		6 Months Ended
	May 29, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Acquisition of Microsemi, net of cash acquired		$ 0.0	$ 7,850.6
Microsemi Corporation
Business Acquisition [Line Items]
Cash paid for shares	$ 8,190.0
Non cash consideration of certain share-based payment awards	53.9
Total consideration transferred	8,240.0
Liabilities assumed	3,232.6
Payments to acquire businesses portion funded by additional line of credit borrowings	8,100.0
Transaction and other fees incurred in transaction	$ 22.0
Useful life (in years)	13 years
Deferred tax liabilities	$ 856.7
Microsemi Corporation \| Backlog
Business Acquisition [Line Items]
Useful life (in years)	1 year
Revolving Credit Facility \| Microsemi Corporation
Business Acquisition [Line Items]
Payments to acquire businesses portion funded by additional line of credit borrowings	$ 3,100.0
Term Loan Facility \| Microsemi Corporation
Business Acquisition [Line Items]
Payments to acquire businesses portion funded by additional line of credit borrowings	3,000.0
Senior Secured Notes \| Microsemi Corporation
Business Acquisition [Line Items]
Payments to acquire businesses portion funded by additional line of credit borrowings	2,000.0
Other Liabilities \| Microsemi Corporation
Business Acquisition [Line Items]
Acquisition of Microsemi, net of cash acquired	$ 2,060.0