Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income tax expense	$ 524.0	$ 299.1	$ 1,316.5	$ 784.1
Effective tax rate (percent)	24.00%	21.10%	23.70%	21.60%
Deferred tax assets net of DTL	$ 177.7		$ 177.7		$ 159.5
Valuation allowance for deferred income taxes	$ 20.3		$ 20.3		$ 4.2