Retirement Benefit Plans - Narrative (Details)	12 Months Ended
	Sep. 30, 2025 USD ($) plan	Sep. 30, 2024 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit pension plans | plan	3
Decrease in benefit obligation	$ 1,654,000
Benefit obligation	19,234,000	$ 20,888,000		$ 20,345,000
Employer contributions	$ 447,000
Other debt withdrawal liability			$ 739,000
Employer matching contribution percentage of employees' gross pay	100.00%
Percentage of eligible compensation of deferral contribution, minimum	1.00%
Percentage of eligible compensation	80.00%
Percentage of eligible compensation of deferral contribution, maximum	6.00%
Matching contribution expense for defined contribution plan	$ 534,000	550,000
Number of company sponsored defined benefit pension plans | plan	2
Non-elective contribution expense	$ 244,000	$ 228,000
Maximum
Defined Benefit Plan Disclosure [Line Items]
Non-elective contribution (in dollars per hour of work)	1.50
Minimum
Defined Benefit Plan Disclosure [Line Items]
Non-elective contribution (in dollars per hour of work)	$ 1.25
IAM National Pension Fund
Defined Benefit Plan Disclosure [Line Items]
Payment period			20 years