v3.26.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]        
Balance as of beginning of period $ 2,472,335 $ 2,312,684 $ 2,391,666 $ 2,200,443
Amounts reclassified from accumulated other comprehensive loss, net of tax 258 67 516 135
Balance as of end of period 2,648,557 2,477,907 2,648,557 2,477,907
Tax on amounts reclassified from accumulated other comprehensive loss (78) (22) (156) (43)
Total        
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]        
Balance as of beginning of period (11,205) (6,453) (11,463) (6,521)
Balance as of end of period (10,947) (6,386) (10,947) (6,386)
Cash Flow Hedges        
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]        
Balance as of beginning of period (4,899) (5,952) (5,163) (6,215)
Amounts reclassified from accumulated other comprehensive loss, net of tax 262 263 526 526
Balance as of end of period (4,637) (5,689) (4,637) (5,689)
Tax on amounts reclassified from accumulated other comprehensive loss (80) (80) (159) (159)
Postemployment Benefit Obligation        
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]        
Balance as of beginning of period (6,306) (501) (6,300) (306)
Amounts reclassified from accumulated other comprehensive loss, net of tax (4) (196) (10) (391)
Balance as of end of period (6,310) (697) (6,310) (697)
Tax on amounts reclassified from accumulated other comprehensive loss $ 2 $ 58 $ 3 $ 116