SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	$ 2,391,666	$ 2,200,443
Amounts reclassified from accumulated other comprehensive loss, net of tax	258	68
Balance as of end of period	2,472,335	2,312,684
Tax on amounts reclassified from accumulated other comprehensive loss	(78)	(21)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(11,463)	(6,521)
Balance as of end of period	(11,205)	(6,453)
Cash Flow Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(5,163)	(6,215)
Amounts reclassified from accumulated other comprehensive loss, net of tax	264	263
Balance as of end of period	(4,899)	(5,952)
Tax on amounts reclassified from accumulated other comprehensive loss	(79)	(79)
Postemployment Benefit Obligation
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(6,300)	(306)
Amounts reclassified from accumulated other comprehensive loss, net of tax	(6)	(195)
Balance as of end of period	(6,306)	(501)
Tax on amounts reclassified from accumulated other comprehensive loss	$ 1	$ 58