Comprehensive Income (Loss) and Changes in Accumulated Other Comprehensive Income (Loss) by Component - Other (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Accumulated other comprehensive income (loss)
Balance	$ 343,321	$ 301,501	$ 296,275
Other comprehensive income	1,249	62,260	19,320
Balance	375,488	343,321	301,501
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Balance	(12,341)	(74,601)	(80,638)
Other comprehensive income (loss) before reclassifications	1,250	56,151
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)		(1,854)
Other comprehensive income	1,249	62,260	19,320
Balance	(11,092)	(12,341)	(74,601)
Accumulated Defined Benefit Plans Adjustment | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Balance	(14,791)	(65,393)
Other comprehensive income (loss) before reclassifications	(2,557)	44,493
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	(56)	(1,854)
Other comprehensive income	(2,374)	50,602
Balance	(17,165)	(14,791)	(65,393)
Accumulated Defined Benefit Plans Adjustment | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Balance	9,017	613
Other comprehensive income (loss) before reclassifications	15,624	8,404
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	56
Other comprehensive income	15,440	8,404
Balance	24,457	9,017	613
Pension and postretirement: Less: amortization of prior service cost
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	239	228
Other comprehensive income	183	176	170
Pension and postretirement: Less: amortization of prior service cost | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	239	228
Pension and postretirement: Less: amortization of gain (loss)
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(240)	7,735
Other comprehensive income	(184)	5,933	6,720
Pension and postretirement: Less: amortization of gain (loss) | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax		7,735
Pension and postretirement: Less: amortization of gain (loss) | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(240)
Accumulated Translation Adjustment
Accumulated other comprehensive income (loss)
Balance	(6,567)	(9,821)
Other comprehensive income (loss) before reclassifications	(11,817)	3,254
Other comprehensive income	(11,817)	3,254	3,690
Balance	$ (18,384)	$ (6,567)	$ (9,821)