Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated other comprehensive income (loss)
Balance	$ 345,310	$ 293,891	$ 343,321	$ 301,501
Other comprehensive income (loss)	(5,169)	2,355	(6,030)	9,992
Balance	354,073	295,012	354,073	295,012
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Balance	(13,202)	(66,964)	(12,341)	(74,601)
Other comprehensive income (loss) before reclassifications	(5,169)	827	(6,029)	5,409
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	1	(463)		(1,390)
Other comprehensive income (loss)	(5,169)	2,355	(6,030)	9,992
Balance	(18,371)	(64,609)	(18,371)	(64,609)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Balance	(14,700)	(62,338)	(14,791)	(65,393)
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	(12)	(463)	(41)	(1,390)
Other comprehensive income (loss)	47	1,528	138	4,583
Balance	(14,653)	(60,810)	(14,653)	(60,810)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Balance	8,925	613	9,017	613
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	13		41
Other comprehensive income (loss)	(47)		(139)
Balance	8,878	613	8,878	613
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	(52)	1,940	(155)	5,819
Actuarial losses | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	8	1,940	25	5,819
Actuarial losses | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(60)		(180)
Accumulated Translation Adjustment
Accumulated other comprehensive income (loss)
Balance	(7,427)	(5,239)	(6,567)	(9,821)
Other comprehensive income (loss) before reclassifications	(5,169)	827	(6,029)	5,409
Other comprehensive income (loss)	(5,169)	827	(6,029)	5,409
Balance	$ (12,596)	$ (4,412)	$ (12,596)	$ (4,412)