Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Income Tax Disclosure [Abstract]
Income tax benefit	$ 695.4	$ 8.7	$ 698.5	$ 649.3
Cost to establish reserves for uncertain tax positions				22.5
Effective income tax rate reconciliation, foreign derived income, amount				15.2
Valuation allowance against deferred tax assets		41.8		41.8
Tax reform adjustment related to deemed foreign dividends				34.9
Unrecognized tax benefits		$ 67.8		67.8
Net tax benefit related to legal, executive separation, and other professional service fees in connection with response to proxy contest				14.6
Repatriation of foreign earnings				$ 31.4