OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Amounts Reclassified From Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2026	Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax benefit	$ (25,660)			$ 47,105			$ (63,849)	$ 8,589
Net income (loss)	51,632	$ 19,318	$ 64,387	(120,139)	$ 56,762	$ 70,851	135,337	7,474
Total | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss) before tax	(1,622)			(390)			(4,864)	(1,188)
Tax benefit	341			82			1,021	249
Net income (loss)	(1,281)			(308)			(3,843)	(939)
Pension amortization | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss) before tax	(1,781)			(95)			(5,345)	(285)
Cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss) before tax	$ 159			$ (295)			$ 481	$ (903)