Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Accumulated other comprehensive income (loss)
Balance	$ 340,209	$ 297,891	$ 343,321	$ 301,501
Other comprehensive income (loss)	(1,430)	1,259	(861)	7,637
Balance	345,310	293,891	345,310	293,891
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Balance	(11,772)	(68,223)	(12,341)	(74,601)
Other comprehensive income (loss) before reclassifications	(1,429)	(268)	(860)	4,582
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	(2)	(464)	(1)	(927)
Other comprehensive income (loss)	(1,430)	1,259	(861)	7,637
Balance	(13,202)	(66,964)	(13,202)	(66,964)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Balance	(14,745)	(63,865)	(14,791)	(65,393)
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	(16)	(464)	(29)	(927)
Other comprehensive income (loss)	45	1,527	91	3,055
Balance	(14,700)	(62,338)	(14,700)	(62,338)
Accumulated Other Comprehensive Income (Loss) | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Balance	8,971	613	9,017	613
Amounts reclassified from accumulated other comprehensive income (loss), Tax provision (benefit)	14		28
Other comprehensive income (loss)	(46)		(92)
Balance	8,925	613	8,925	613
Amortization of Pension and Postretirement Plan items
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	52	52	103	103
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	52	52	103	103
Actuarial losses
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(51)	1,939	(103)	3,879
Actuarial losses | Defined Benefit Pension Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	9	1,939	17	3,879
Actuarial losses | Defined Benefit Other Postretirement Benefit Plan
Accumulated other comprehensive income (loss)
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(60)		(120)
Accumulated Translation Adjustment
Accumulated other comprehensive income (loss)
Balance	(5,998)	(4,971)	(6,567)	(9,821)
Other comprehensive income (loss) before reclassifications	(1,429)	(268)	(860)	4,582
Other comprehensive income (loss)	(1,429)	(268)	(860)	4,582
Balance	$ (7,427)	$ (5,239)	$ (7,427)	$ (5,239)