Revenues from Contracts with Customers - Other Information (Details) $ in Thousands, lb in Millions		12 Months Ended
	Nov. 17, 2006 USD ($) lb	Sep. 30, 2023 USD ($) lb	Sep. 30, 2022 USD ($)
Revenues from Contracts with Customers
Accounts receivable, gross		$ 106,751	$ 95,340
Accounts receivable, allowance for doubtful accounts		459	428
Contract liabilities		$ 7,829	10,329
Revenue, Remaining Performance Obligation, Optional Exemption, Performance Obligation		true
Estimated product returns		$ 810	$ 700
Conversion Services Arrangement
Revenues from Contracts with Customers
Revenue recognition period	20 years
Advance payments received	$ 50,000
Conversion Services Arrangement | Maximum
Revenues from Contracts with Customers
Annual volume of titanium metal to be converted (in pounds) | lb	10	10