Changes in Accumulated Other Comprehensive Income (Loss) by Component - Other (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated other comprehensive income (loss)
Balance	$ 405,759	$ 345,310	$ 375,488	$ 343,321
Other comprehensive income (loss)	937	(5,169)	7,890	(6,030)
Balance	413,501	354,073	413,501	354,073
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Balance	(4,139)	(13,202)	(11,092)	(12,341)
Other comprehensive income (loss) before reclassifications	1,330	(5,169)	9,069	(6,029)
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	119	1	355
Other comprehensive income (loss)	937	(5,169)	7,890	(6,030)
Amounts reclassified from accumulated other comprehensive income (loss)	(3,202)
Balance	(3,202)	(18,371)	(3,202)	(18,371)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Balance	(17,075)	(14,700)	(17,165)	(14,791)
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	(14)	(12)	(41)	(41)
Other comprehensive income (loss)	44	47	134	138
Amounts reclassified from accumulated other comprehensive income (loss)	(17,031)
Balance	(17,031)	(14,653)	(17,031)	(14,653)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Balance	23,581	8,925	24,457	9,017
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	133	13	396	41
Other comprehensive income (loss)	(437)	(47)	(1,313)	(139)
Amounts reclassified from accumulated other comprehensive income (loss)	23,144
Balance	23,144	8,878	23,144	8,878
Amortization of Pension and Postretirement Plan items
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	51	51	154	154
Amortization of Pension and Postretirement Plan items | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	51	51	154	154
Actuarial losses
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(563)	(52)	(1,688)	(155)
Actuarial losses | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	7	8	21	25
Actuarial losses | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(570)	(60)	(1,709)	(180)
Accumulated Translation Adjustment
Accumulated other comprehensive income (loss)
Balance	(10,645)	(7,427)	(18,384)	(6,567)
Other comprehensive income (loss) before reclassifications	1,330	(5,169)	9,069	(6,029)
Other comprehensive income (loss)	1,330	(5,169)	9,069	(6,029)
Amounts reclassified from accumulated other comprehensive income (loss)	(9,315)
Balance	$ (9,315)	$ (12,596)	$ (9,315)	$ (12,596)