SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	$ 2,200,443	$ 1,990,735
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	68	395
Balance as of end of period	2,312,684	2,066,201
Tax on amounts reclassified from accumulated other comprehensive income (loss)	(21)	(119)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(6,521)	(9,959)
Balance as of end of period	(6,453)	(9,564)
Cash Flow Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(6,215)	(7,269)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	263	264
Balance as of end of period	(5,952)	(7,005)
Tax on amounts reclassified from accumulated other comprehensive income (loss)	(79)	(79)
Postemployment Benefit Obligation
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(306)	(2,690)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(195)	131
Balance as of end of period	(501)	(2,559)
Tax on amounts reclassified from accumulated other comprehensive income (loss)	$ 58	$ (40)