Summary of Significant Accounting Policies - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	$ 34,335	$ 40,690
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	40,690	49,622
Ending balance	34,335	40,690
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(5,928)	(6,196)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(6,196)	(5,359)
Other comprehensive income (loss) before reclassifications	268	(837)
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive income (loss)	268	(837)
Ending balance	(5,928)	(6,196)
Retirement Plan Liability Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(741)	(2,509)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,509)	(3,720)
Other comprehensive income (loss) before reclassifications	1,341	527
Amounts reclassified from accumulated other comprehensive loss	427	684
Net current-period other comprehensive income (loss)	1,768	1,211
Ending balance	(741)	(2,509)
Interest Rates Swap Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	9	12
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	12	0
Other comprehensive income (loss) before reclassifications	(3)	12
Amounts reclassified from accumulated other comprehensive loss
Net current-period other comprehensive income (loss)	(3)	12
Ending balance	9	12
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(6,660)	(8,693)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,693)	(9,079)
Other comprehensive income (loss) before reclassifications	1,606	(298)
Amounts reclassified from accumulated other comprehensive loss	427	684
Net current-period other comprehensive income (loss)	2,033	386
Ending balance	$ (6,660)	$ (8,693)