v3.25.2
Litigation, Claims and Contingencies - Summary of Progression of Insurance Receivable (Parenthetical) (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Sep. 30, 2024
Jun. 30, 2024
Sep. 30, 2023
Sep. 30, 2022
Sep. 30, 2021
Ashland [Member]            
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]            
Insurance receivable $ 96 [1],[2] $ 97 [1],[2] $ 100 [1],[2] $ 95 [1],[2] $ 101 [1],[2] $ 100
Total allowance for credit losses 1 1        
Ashland [Member] | Accounts Receivable [Member]            
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]            
Insurance receivable 10 9        
Hercules [Member]            
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]            
Insurance receivable 49 [3],[4] 50 [3],[4] $ 51 [3],[4] $ 47 [3],[4] $ 52 [3],[4] $ 47
Total allowance for credit losses 1 1        
Hercules [Member] | Accounts Receivable [Member]            
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]            
Insurance receivable $ 6 $ 6        
[1] Includes $10 million and $9 million classified in accounts receivable, net on the Condensed Consolidated Balance Sheets at June 30, 2025 and September 30, 2024, respectively.
[2] The total allowance for credit losses was $1 million at June 30, 2025 and September 30, 2024.
[3] Includes $6 million classified in accounts receivable, net on the Condensed Consolidated Balance Sheets at both June 30, 2025 and September 30, 2024.
[4] The total allowance for credit losses was $1 million at June 30, 2025 and September 30, 2024.