Retirement Benefit Plans - Net Plan Assets Recognized in the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Reconciliation of funded status:
Plan assets less than projected benefit obligations	$ (3,463)	$ (4,858)
Amounts recognized in accumulated other comprehensive loss:
Net loss	4,504	6,271
Net amount recognized in the consolidated balance sheets	1,041	1,413
Amounts recognized in the consolidated balance sheets are:
Accumulated other comprehensive loss – pretax	4,504	6,271
Accrued liabilities
Amounts recognized in the consolidated balance sheets are:
Liabilities	(46)	(46)
Pension liability
Amounts recognized in the consolidated balance sheets are:
Liabilities	$ (3,417)	$ (4,812)