Retirement Benefit Plans - Narrative (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2023 USD ($) plan	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit pension plans | plan		4
Decrease in benefit obligation		$ 2,138,000
Benefit obligation		20,657,000	$ 22,795,000	$ 29,330,000
Employer contributions		$ 93,000
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		$ 516,000	528,000
Number of company sponsored defined benefit pension plans | plan		2
Non-elective contribution expense		$ 222,000	$ 204,000
Maximum
Defined Benefit Plan Disclosure [Line Items]
Non-elective contribution per hour		1.50
Minimum
Defined Benefit Plan Disclosure [Line Items]
Non-elective contribution per hour		$ 1.25
IAM National Pension Fund
Defined Benefit Plan Disclosure [Line Items]
Payment period	20 years