Identifiable Intangible Assets Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	12 years
Amortization	$ 28.2	$ 27.0	$ 22.8
Software and Software Development Costs [Member]
Finite-Lived Intangible Asset, Useful Life	6 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years
Amortization	$ 3.3	3.3	2.9
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3.2
Finite-Lived Intangible Assets, Amortization Expense, Year Two	2.7
Finite-Lived Intangible Assets, Amortization Expense, Year Three	2.2
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1.5
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 0.8
Customer Relationships [Member]
Finite-Lived Intangible Asset, Useful Life	4 years 2 months 12 days
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Asset, Useful Life	3 years 10 months 24 days
Business Combination-Related Identifiable Intangible [Member]
Amortization	$ 24.9	$ 23.7	$ 19.9
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	24.9
Finite-Lived Intangible Assets, Amortization Expense, Year Two	24.7
Finite-Lived Intangible Assets, Amortization Expense, Year Three	24.7
Finite-Lived Intangible Assets, Amortization Expense, Year Four	24.3
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 4.8