Litigation, Claims and Contingencies - Summary of Asbestos Claims Activity (Details) - Claim Claim in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Ashland [Member]
Asbestos claims [Roll Forward]
Open claims - beginning of year	44	46	49
New claims filed	2	2	2
Claims settled	(1)	(1)	(1)
Claims dismissed	(3)	(3)	(4)
Open claims - end of year	42	44	46
Hercules [Member]
Asbestos claims [Roll Forward]
Open claims - beginning of year	11	12	12
New claims filed	1	1	1
Claims dismissed	0	(2)	(1)
Open claims - end of year	12	11	12