Income Taxes - Effective Tax Rate-Business and Asset Actions (Details) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)
Income Tax Disclosure [Abstract]
Business and asset actions, including equity affiliate income	$ 2,934.7	$ 2,934.7
Restructuring charges tax benefit	640.6
Cost to establish reserves for uncertain tax positions	22.5
Effective income tax rate reconciliation, foreign derived income, amount	13.1
Valuation allowance against deferred tax assets	$ 41.8	$ 41.8