Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Discrete net tax expense related to Tax Act		$ 40.6
Reversal of non-recurring benefit related to U.S. taxation of deemed foreign dividends		56.2
Tax benefit related to finalization of assessment of impacts of Tax Act		$ (15.6)
Effective tax rate (percent)	19.80%	27.00%
Income tax payments, net of refunds	$ 66.2	$ 28.7