Income Taxes - Deferred Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Deferred tax assets:
Pension and postretirement benefits	$ 12,045	$ 16,802
Inventories	4,341	3,225
Accrued compensation and benefits	1,451	2,096
Accrued expenses and other	2,526	2,600
Tax attributes	5,596	5,625
Other assets	1,077	250
Valuation allowance	(5,052)	(4,695)
Total deferred tax assets	23,785	28,299
Deferred tax liabilities:
Property, plant and equipment, net	(22,056)	(24,081)
Intangible and other	(1,511)	(1,414)
Other liabilities	(296)	(227)
Total deferred tax liabilities	(23,863)	(25,722)
Net deferred tax assets (liabilities)		2,577
Net deferred tax assets (liabilities)	(78)
Conversion Services Arrangement
Deferred tax assets:
TIMET Agreement	$ 1,801	$ 2,396