v3.25.2
Goodwill and Other Intangible Assets - Summary of Goodwill by Reportable Segment (Parenthetical) (Details) - USD ($)
$ in Millions
 9 Months Ended
Jun. 30, 2025
Sep. 30, 2024
Goodwill [Line Items]    
Amount allocated to Avoca disposal group [1] $ 1  
Discontinued Operations, Held-for-sale [Member]    
Goodwill [Line Items]    
Amount allocated to Avoca disposal group 1  
Life Sciences [Member]    
Goodwill [Line Items]    
Accumulated impairment 375 $ 0
Amount allocated to Avoca disposal group [1] 0  
Personal Care [Member]    
Goodwill [Line Items]    
Accumulated impairment 356 356
Amount allocated to Avoca disposal group [1],[2] 1  
Specialty Additives [Member]    
Goodwill [Line Items]    
Accumulated impairment 505 174
Amount allocated to Avoca disposal group [1],[2] 0  
Intermediates [Member]    
Goodwill [Line Items]    
Accumulated impairment 90 $ 90
Amount allocated to Avoca disposal group [1],[2] $ 0  
[1] Ashland allocated $1 million to the Avoca business during the nine months ended June 30, 2025. See Note B of the Notes to the Condensed Consolidated Financial Statements for more information.
(c)
As of June 30, 2025, there were accumulated impairments of $375 million, $356 million, $505 million and $90 million related to the Life Sciences, Personal Care, Specialty Additives and Intermediates reportable segments, respectively.
[2] As of September 30, 2024, there were accumulated impairments of zero, $356 million, $174 million and $90 million related to the Life Sciences, Personal Care, Specialty Additives and Intermediates reportable segments, respectively.