v3.25.2
Fair Value Measurements - Summary of Financial Instruments Subject to Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Millions
Jun. 30, 2025
Sep. 30, 2024
Carrying (Reported) Amount, Fair Value Disclosure [Member]    
Assets    
Cash and cash equivalents $ 207 $ 300
Restricted investments 350 [1],[2] 368 [3],[4]
Investment of captive insurance company 3 [5] 7 [6]
Foreign currency derivatives 2 [7] 1 [8]
Total assets at fair value 563 676
Liabilities    
Foreign currency derivatives 1 [9] 1 [10]
Total liabilities at fair value 1 3
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives $ 1  
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Accounts Receivable, after Allowance for Credit Loss, Current  
Liabilities    
Commodity derivatives [10]   $ 2
Derivative Liability, Statement of Financial Position [Extensible Enumeration]   Accrued Liabilities, Current
Estimate of Fair Value, Fair Value Disclosure [Member]    
Assets    
Cash and cash equivalents $ 207 $ 300
Restricted investments 350 [1],[2] 368 [3],[4]
Investment of captive insurance company 3 [5] 7 [6]
Foreign currency derivatives 2 [7] 1 [8]
Total assets at fair value 563 676
Liabilities    
Foreign currency derivatives 1 [9] 1 [10]
Total liabilities at fair value 1 3
Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives $ 1  
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Accounts Receivable, after Allowance for Credit Loss, Current  
Liabilities    
Commodity derivatives [10]   $ 2
Derivative Liability, Statement of Financial Position [Extensible Enumeration]   Accrued Liabilities, Current
Fair Value, Inputs, Level 1 [Member]    
Assets    
Cash and cash equivalents $ 207 $ 300
Restricted investments 350 [1],[2] 368 [3],[4]
Investment of captive insurance company 3 [5] 7 [6]
Foreign currency derivatives 0 [7] 0 [8]
Total assets at fair value 560 675
Liabilities    
Foreign currency derivatives 0 [9] 0 [10]
Total liabilities at fair value 0 0
Fair Value, Inputs, Level 1 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives 0  
Liabilities    
Commodity derivatives [10]   0
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]
Foreign currency derivatives 2 [7] 1 [8]
Total assets at fair value 3 1
Liabilities    
Foreign currency derivatives 1 [9] 1 [10]
Total liabilities at fair value 1 3
Fair Value, Inputs, Level 2 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives 1  
Liabilities    
Commodity derivatives [10]   2
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]
Foreign currency derivatives 0 [7] 0 [8]
Total assets at fair value 0 0
Liabilities    
Foreign currency derivatives 0 [9] 0 [10]
Total liabilities at fair value 0 0
Fair Value, Inputs, Level 3 [Member] | Commodity Derivatives [Member]    
Assets    
Commodity derivatives $ 0  
Liabilities    
Commodity derivatives [10]   $ 0
[1] Includes $228 million related to the Asbestos trust and $122 million related to the Environmental trust.
[2] Includes $283 million within restricted investments and $67 million within other current assets in the Condensed Consolidated Balance Sheet
[3] Includes $248 million related to the Asbestos trust and $120 million related to the Environmental trust
[4] Includes $295 million within restricted investments and $73 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 accounts receivable, net in the Condensed Consolidated Balance Sheet.
[8] Included in accounts receivable, net in the Condensed Consolidated Balance Sheet.
[9] Included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet.
[10] Included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet.