v3.26.1
Summary of Significant Accounting Policies (Schedule of Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Other Comprehensive Gains and Losses Before Reclassifications $ (1,604) $ (152,786) $ 34,349 $ (191,899)
Amounts Reclassified From Other Comprehensive Loss 35,705 5,964 25,984 (15,600)
Gains and Losses on Derivative Financial Instruments        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance 46,182 (4,878) 19,950 55,799
Other Comprehensive Gains and Losses Before Reclassifications (1,604) (152,786) 34,349 (191,899)
Amounts Reclassified From Other Comprehensive Loss 35,705 5,964 25,984 (15,600)
Ending balance 80,283 (151,700) 80,283 (151,700)
Funded Status of the Pension and Other Post-Retirement Benefit Plans        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance (79,172) (71,275) (79,172) (71,275)
Other Comprehensive Gains and Losses Before Reclassifications 0 0 0 0
Amounts Reclassified From Other Comprehensive Loss 0 0 0 0
Ending balance (79,172) (71,275) (79,172) (71,275)
Accumulated Other Comprehensive Income (Loss)        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance (32,990) (76,153) (59,222) (15,476)
Ending balance $ 1,111 $ (222,975) $ 1,111 $ (222,975)