CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 62,041	$ 81,379	$ 75,580	$ 95,868
Other comprehensive income (loss):
Unrealized gain on pension plan obligation	382	224	762	448
Tax effect of unrealized gain on pension plan obligation	(104)	(61)	(201)	(106)
Unrealized gain (loss) on captive insurance collateral	775	(2,062)	1,130	(2,674)
Tax effect of unrealized gain (loss) on captive insurance collateral	(164)	435	(238)	564
Unrealized gain (loss) on interest rate hedges	(704)	1,549	(1,081)	2,267
Tax effect of unrealized gain (loss) on interest rate hedges	186	(410)	288	(603)
Total other comprehensive income (loss)	371	(325)	660	(104)
Total comprehensive income	$ 62,412	$ 81,054	$ 76,240	$ 95,764