Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2023	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2023
Variable Interest Entity [Line Items]
Unrecorded Unconditional Purchase Obligation		$ 16,118.0	$ 16,118.0
Operating lease right-of-use assets, net		974.0	974.0	$ 694.8
Use of cash for payments on operating leases			337.8	128.0	$ 98.8
NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Unrecorded Unconditional Purchase Obligation		5,000.0	5,000.0
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Value of engineering, procurement, and construction agreement	$ 6,700.0
Operating lease right-of-use assets, net		228.9	$ 228.9	$ 0.0
Voting interest in joint venture			33.33333%
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company | Land
Variable Interest Entity [Line Items]
Lessee, Operating Lease, Term of Contract						50 years
Operating lease right-of-use assets, net		223.0	$ 223.0
Use of cash for payments on operating leases		$ 209.0	$ 209.0
Lessee, Operating Lease, Years Additional Payments Due After Commencement		30 years	30 years