Acquisitions and Dispositions - Components of the Preliminary Mountaineer Purchase Price Allocation (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 01, 2021
Liabilities assumed:
Goodwill	$ 3,027	$ 3,612	$ 3,770
Mountaineer
Assets acquired:
Cash and cash equivalents				$ 3
Accounts receivable				14
Inventories				41
Other current assets				21
Property, plant and equipment				397
Other noncurrent assets				48
Total assets acquired				524
Liabilities assumed:
Short-term borrowings				55
Accounts payable				20
Other current liabilities				52
Long-term debt				164
Pension and other postretirement benefit obligation				33
Deferred income taxes				21
Other noncurrent liabilities				29
Total liabilities assumed				374
Goodwill				250
Net consideration transferred				$ 400