v3.25.2
Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Details) - USD ($)
$ in Millions
 9 Months Ended 12 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2022
Ashland [Member]          
Asbestos reserve [Roll Forward]          
Asbestos reserve - beginning of year $ 274 [1] $ 281 [1] $ 281 [1] $ 305 [1] $ 320
Reserve adjustment 16 24 24 9 16
Amounts paid (25) (23) (31) (33) (31)
Asbestos reserve - end of period [1] 265 282 274 281 305
Hercules [Member]          
Asbestos reserve [Roll Forward]          
Asbestos reserve - beginning of year 185 [2] 191 [2] 191 [2] 213 [2] 217
Reserve adjustment 10 14 14 (2) 15
Amounts paid (10) (15) (20) (20) (19)
Asbestos reserve - end of period [2] $ 185 $ 190 $ 185 $ 191 $ 213
[1] Includes $29 million and $28 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of June 30, 2025 and September 30, 2024, respectively.
[2] Includes $17 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets at both June 30, 2025 and September 30, 2024.