Summary of Significant Accounting Policies - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	$ 40,690	$ 49,622
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	49,622	45,523
Other comprehensive income (loss) before reclassifications	(298)	3,269
Amounts reclassified from accumulated other comprehensive loss	684	1,120
Net current-period other comprehensive income (loss)	386	4,389
Ending balance	40,690	49,622
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI tax benefit	0	0
Total accumulated other comprehensive loss	(6,196)	(5,359)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,359)	(5,257)
Other comprehensive income (loss) before reclassifications	(837)	(102)
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive income (loss)	(837)	(102)
Ending balance	(6,196)	(5,359)
Retirement Plan Liability Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI tax benefit	(3,758)	(3,758)
Total accumulated other comprehensive loss	(2,509)	(3,720)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,720)	(8,211)
Other comprehensive income (loss) before reclassifications	527	3,371
Amounts reclassified from accumulated other comprehensive loss	684	1,120
Net current-period other comprehensive income (loss)	1,211	4,491
Ending balance	(2,509)	(3,720)
Interest Rates Swap Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI tax benefit	0	0
Total accumulated other comprehensive loss	12	0
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	0
Other comprehensive income (loss) before reclassifications	12	0
Amounts reclassified from accumulated other comprehensive loss		0
Net current-period other comprehensive income (loss)	12	0
Ending balance	12	0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive loss	(8,693)	(9,079)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(9,079)	(13,468)
Ending balance	$ (8,693)	$ (9,079)