CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 274,922	$ 117,890	$ 163,007
Other comprehensive income (loss), net of tax:
Reclassifications of losses to net income on derivatives designated as hedging instruments, net of tax of $(317), $(350) and $(32), respectively	1,054	1,021	108
Loss on derivatives designated as hedging instruments, net of tax of $0, $0 and $3,203, respectively	0	0	(10,505)
Adjustment to postemployment benefit obligation, net of tax of $(8,657), $(2,575) and $567, respectively	28,648	8,766	(2,131)
Net current-period other comprehensive income, net of tax	29,702	9,787	(12,528)
Comprehensive income	$ 304,624	$ 127,677	$ 150,479