Supplemental Information (NEOM Green Hydrogen Project) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Variable Interest Entity [Line Items]
Cash and cash items	$ 2,711.0	$ 4,468.9
Other receivables and current assets	515.8	550.9
Plant and equipment, net	14,160.5	13,254.6	$ 11,964.7
Payables and accrued liabilities	2,771.6	2,218.3
Long-term debt – related party	652.0	274.6
Noncontrolling Interests	$ 558.4	$ 548.3
Variable Interest Entity, Primary Beneficiary [Member] | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Voting interest in joint venture	33.30%
Cash and cash items	$ 275.0
Other receivables and current assets	23.0
Plant and equipment, net	219.0
Payables and accrued liabilities	58.0
Long-term debt – related party	447.0
Noncontrolling Interests	$ 30.0