Business Acquisitions - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Assets acquired
Goodwill	$ 6,782.0			$ 2,299.0
Microsemi Corporation
Assets acquired
Cash and cash equivalents	340.0	$ 340.0
Accounts receivable	216.1	216.1
Inventories	571.5	625.0
Inventories, adjustments	(53.5)
Other current assets	85.2	66.6
Other current assets, adjustments	18.6
Property, plant and equipment	201.9	201.9
Property, plant and equipment, adjustments	0.0
Goodwill	4,483.0	4,488.5
Goodwill, adjustment	(5.5)
Purchased intangible assets	5,466.9	5,466.9
Purchased intangible assets, adjustments	0.0
Long-term deferred tax assets	6.0	6.0
Long-term deferred tax assets, adjustments	0.0
Other assets	57.2	57.2
Other assets, adjustments	0.0
Total assets acquired	11,427.8	11,468.2
Total assets acquired, adjustments	(40.4)
Liabilities assumed
Accounts payable	(233.8)	(226.9)
Accounts payable, adjustments	(6.9)
Other current liabilities	(169.4)	(174.8)
Other current liabilities, adjustments	5.4
Long-term debt	(2,056.9)	(2,056.9)
Deferred tax liabilities	(604.7)	(617.2)
Deferred tax liabilities, adjustments	12.5
Long-term income tax payable	(87.2)	(101.6)
Long-term income tax payable, adjustments	14.4
Other long-term liabilities	(31.3)	(46.3)
Other long-term liabilities, adjustments	15.0
Total liabilities assumed	(3,183.3)	(3,223.7)	$ (3,180.0)
Total liabilities assumed, adjustments	40.4
Purchase price allocated	8,244.5	$ 8,244.5
Purchase price allocated, adjustments	$ 0.0