Fair Value Measurements (Schedule of Nonrecurring Fair Value Measurements) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Plant and equipment, net	$ 25,337.8	$ 23,370.9	$ 17,472.1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant and equipment, net	25,337.8	$ 23,370.9	$ 17,472.1
Project Exit Costs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of long lived assets to be disposed of	2,500.0
Fair Value, Nonrecurring | Project Exit Costs
Fair Value Disclosures [Abstract]
Plant and equipment, net	22.5
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale	418.3
Plant and equipment, net	22.5
Fair Value, Nonrecurring | Project Exit Costs | Assets held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of long lived assets to be disposed of	350.6
Fair Value, Nonrecurring | Project Exit Costs | Plant and equipment, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of long lived assets to be disposed of	2,116.2
Fair Value, Nonrecurring | Project Exit Costs | Level 3
Fair Value Disclosures [Abstract]
Plant and equipment, net	22.5
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale	418.3
Plant and equipment, net	$ 22.5