Acquisitions (Fair Values Of The Assets Acquired And Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 13, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Trade accounts receivable		$ 9.0	$ 41.1	$ 21.6
Inventories		9.3	14.8	20.9
Property, plant and equipment		3.9	88.4	9.0
Goodwill		217.1	1,275.4	264.8
Other intangible assets, primarily customer relationships, trade names and technology		113.6	850.7	154.5
Trade accounts payable		(3.2)	(6.7)	(9.9)
Other assets and liabilities, net		(18.4)	(66.5)	(75.1)
Net assets acquired		331.3	2,197.2	385.8
Less: noncash consideration		0.0	(23.9)	0.0
Net cash consideration		331.3	2,173.3	385.8
IDT
Business Acquisition [Line Items]
Trade accounts receivable			36.0
Inventories			14.8
Property, plant and equipment			88.2
Goodwill	$ 1,200.0		1,212.6
Other intangible assets, primarily customer relationships, trade names and technology			811.0
Trade accounts payable			(5.5)
Other assets and liabilities, net			(55.0)
Net assets acquired			2,102.1
Less: noncash consideration			(23.9)
Net cash consideration	$ 2,100.0		2,078.2
Other businesses acquired
Business Acquisition [Line Items]
Trade accounts receivable			5.1
Inventories			0.0
Property, plant and equipment			0.2
Goodwill		217.0	62.8	265.0
Other intangible assets, primarily customer relationships, trade names and technology			39.7
Trade accounts payable			(1.2)
Other assets and liabilities, net			(11.5)
Net assets acquired			95.1
Less: noncash consideration			0.0
Net cash consideration		$ 331.0	$ 95.1	$ 386.0