Goodwill and Other Intangible Assets Textuals - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amortization of Intangible Assets	$ 15.7	$ 15.1	$ 14.3
Future Amortization Expense, Year One	14.7
Future Amortization Expense, Year Two	13.2
Future Amortization Expense, Year Three	13.5
Future Amortization Expense, Year Four	12.9
Future Amortization Expense, Year Five	11.8
Amortization Of Acquired Intangible Asset Net Of Tax	14.9	14.3	13.3
Purchased Intangibles, Net of Tax	11.2	10.8	10.0
Capitalized Computer Software, Amortization	$ 40.7	$ 34.4	$ 33.0
Minimum [Member]
Finite-Lived Intangible Assets, Useful Life, Minimum	3 years
Maximum [Member]
Finite-Lived Intangible Assets, Useful Life, Minimum	45 years