Goodwill and Other Intangible Assets (Goodwill) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 13,966.0
Additions	13.6
Other	4.0
Currency translation adjustments	5.6
Balance at end of period	13,989.2
Application Software
Goodwill [Roll Forward]
Balance at beginning of period	8,802.3
Additions	13.6
Other	3.1
Currency translation adjustments	1.1
Balance at end of period	8,820.1
Network Software & Systems
Goodwill [Roll Forward]
Balance at beginning of period	3,746.2
Additions	0.0
Other	0.9
Currency translation adjustments	6.8
Balance at end of period	3,753.9
Measurement & Analytical Solutions
Goodwill [Roll Forward]
Balance at beginning of period	1,167.3
Additions	0.0
Other	0.0
Currency translation adjustments	(1.8)
Balance at end of period	1,165.5
Process Technologies
Goodwill [Roll Forward]
Balance at beginning of period	250.2
Additions	0.0
Other	0.0
Currency translation adjustments	(0.5)
Balance at end of period	$ 249.7