v3.26.1
Fair Value Measurements - Summary of Financial Instruments Subject to Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Millions
Jun. 30, 2026
Sep. 30, 2025
Carrying (Reported) Amount, Fair Value Disclosure [Member]    
Assets    
Cash and cash equivalents $ 440 $ 215
Restricted investments 332 [1],[2] 347 [3],[4]
Investment of captive insurance company 7 [5] 5 [6]
Total assets at fair value 779 568
Liabilities    
Foreign currency derivatives 3 [7] 1 [8]
Total liabilities at fair value 5 2
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives [9]   $ 1
Derivative Asset, Statement of Financial Position [Extensible Enumeration]   Accounts Receivable, after Allowance for Credit Loss, Current
Liabilities    
Commodity derivatives $ 2 [7] $ 1 [8]
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Accrued Liabilities, Current Accrued Liabilities, Current
Estimate of Fair Value, Fair Value Disclosure [Member]    
Assets    
Cash and cash equivalents $ 440 $ 215
Restricted investments 332 [1],[2] 347 [3],[4]
Investment of captive insurance company 7 [5] 5 [6]
Total assets at fair value 779 568
Liabilities    
Foreign currency derivatives 3 [7] 1 [8]
Total liabilities at fair value 5 2
Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives [9]   $ 1
Derivative Asset, Statement of Financial Position [Extensible Enumeration]   Accounts Receivable, after Allowance for Credit Loss, Current
Liabilities    
Commodity derivatives $ 2 [7] $ 1 [8]
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Accrued Liabilities, Current Accrued Liabilities, Current
Fair Value, Inputs, Level 1 [Member]    
Assets    
Cash and cash equivalents $ 440 $ 215
Restricted investments 332 [1],[2] 347 [3],[4]
Investment of captive insurance company 7 [5] 5 [6]
Total assets at fair value 779 567
Liabilities    
Foreign currency derivatives 0 [7] 0 [8]
Total liabilities at fair value 0 0
Fair Value, Inputs, Level 1 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives [9]   0
Liabilities    
Commodity derivatives 0 [7] 0 [8]
Fair Value, Inputs, Level 2 [Member]    
Assets    
Cash and cash equivalents 0 0
Restricted investments 0 [1],[2] 0 [3],[4]
Investment of captive insurance company 0 [5] 0 [6]
Total assets at fair value 0 1
Liabilities    
Foreign currency derivatives 3 [7] 1 [8]
Total liabilities at fair value 5 2
Fair Value, Inputs, Level 2 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives [9]   1
Liabilities    
Commodity derivatives 2 [7] 1 [8]
Fair Value, Inputs, Level 3 [Member]    
Assets    
Cash and cash equivalents 0 0
Restricted investments 0 [1],[2] 0 [3],[4]
Investment of captive insurance company 0 [5] 0 [6]
Total assets at fair value 0 0
Liabilities    
Foreign currency derivatives 0 [7] 0 [8]
Total liabilities at fair value 0 0
Fair Value, Inputs, Level 3 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives [9]   0
Liabilities    
Commodity derivatives $ 0 [7] $ 0 [8]
[1] Includes $220 million related to the Asbestos trust and $112 million related to the Environmental trust.
[2] Includes $285 million within restricted investments and $47 million within other current assets in the Condensed Consolidated Balance Sheet.
[3] Includes $231 million related to the Asbestos trust and $116 million related to the Environmental trust.
[4] Includes $297 million within restricted investments and $50 million within other current assets in the Condensed Consolidated Balance Sheet.
[5] Included in other noncurrent assets in the Condensed Consolidated Balance Sheet.
[6] Included in other noncurrent assets in the Condensed Consolidated Balance Sheet.
[7] Included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet.
[8] Included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet.
[9] Included in accounts receivable, net in the Condensed Consolidated Balance Sheet.