SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	$ 1,817,210	$ 1,630,862
Amounts reclassified from accumulated other comprehensive income, net of tax	304	1,030
Balance as of end of period	1,922,795	1,716,978
Tax on amounts reclassified from accumulated other comprehensive income	(91)	(312)
Cash Flow Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(8,322)	(9,376)
Amounts reclassified from accumulated other comprehensive income, net of tax	263	264
Balance as of end of period	(8,059)	(9,112)
Tax on amounts reclassified from accumulated other comprehensive income	(79)	(79)
Postemployment Benefit Obligation
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	3,496	(25,152)
Amounts reclassified from accumulated other comprehensive income, net of tax	41	766
Balance as of end of period	3,537	(24,386)
Tax on amounts reclassified from accumulated other comprehensive income	(12)	(233)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance as of beginning of period	(4,826)	(34,528)
Balance as of end of period	$ (4,522)	$ (33,498)