Retirement Benefit Plans - Net Plan Assets Recognized in the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Reconciliation of funded status:
Plan assets in excess of (less than) projected benefit obligations	$ (832)	$ (2,512)
Assets Exceed Benefit Obligations
Reconciliation of funded status:
Plan assets in excess of (less than) projected benefit obligations	420	0
Amounts recognized in accumulated other comprehensive income (loss):
Net loss	1,459	0
Prior service cost	0	0
Net amount recognized in the consolidated balance sheets	1,879	0
Amounts recognized in the consolidated balance sheets are:
Other assets	420	0
Accumulated other comprehensive income (loss) – pretax	1,459	0
Benefit Obligations Exceed Assets
Reconciliation of funded status:
Plan assets in excess of (less than) projected benefit obligations	(1,252)	(2,512)
Amounts recognized in accumulated other comprehensive income (loss):
Net loss	642	3,599
Prior service cost	0	0
Net amount recognized in the consolidated balance sheets	(610)	1,087
Amounts recognized in the consolidated balance sheets are:
Other assets	0	0
Accumulated other comprehensive income (loss) – pretax	642	3,599
Accrued liabilities | Assets Exceed Benefit Obligations
Amounts recognized in the consolidated balance sheets are:
Liabilities	0	0
Accrued liabilities | Benefit Obligations Exceed Assets
Amounts recognized in the consolidated balance sheets are:
Liabilities	(46)	(47)
Pension liability | Assets Exceed Benefit Obligations
Amounts recognized in the consolidated balance sheets are:
Liabilities	0	0
Pension liability | Benefit Obligations Exceed Assets
Amounts recognized in the consolidated balance sheets are:
Liabilities	$ (1,206)	$ (2,465)