Comprehensive Income (Loss) and Changes in Accumulated Other Comprehensive Income (Loss) by Component - Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Comprehensive Income (Loss)
Net income (loss)	$ 45,087	$ (8,683)	$ (6,478)
Other comprehensive income (loss), Pre-tax	5,173	80,158	24,168
Other comprehensive income (loss), Tax	(3,924)	(17,898)	(4,848)
Other comprehensive income	1,249	62,260	19,320
Comprehensive income	46,336	53,577	12,842
Pension and postretirement: Net gain (loss) arising during period
Comprehensive Income (Loss)
Other comprehensive income (loss), Pre-tax	16,991	68,941	11,121
Other comprehensive income (loss), Tax	(3,924)	(16,044)	(2,381)
Other comprehensive income	13,067	52,897	8,740
Pension and postretirement: Less: amortization of prior service cost
Comprehensive Income (Loss)
Other comprehensive income (loss), Pre-tax	239	228	228
Other comprehensive income (loss), Tax	(56)	(52)	(58)
Other comprehensive income	183	176	170
Pension and postretirement: Less: amortization of gain (loss)
Comprehensive Income (Loss)
Other comprehensive income (loss), Pre-tax	(240)	7,735	9,129
Other comprehensive income (loss), Tax	56	(1,802)	(2,409)
Other comprehensive income	(184)	5,933	6,720
Accumulated Translation Adjustment
Comprehensive Income (Loss)
Other comprehensive income (loss), Pre-tax	(11,817)	3,254	3,690
Other comprehensive income	$ (11,817)	$ 3,254	$ 3,690