v3.26.1
Revenue and Accounts Receivable - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]        
Total operating revenues $ 1,962,402 $ 1,950,502 $ 3,304,987 $ 3,126,501
Distribution        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,876,911 1,881,742 3,134,960 2,990,311
Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Total operating revenues 85,491 68,760 170,027 136,190
Operating Segments        
Disaggregation of Revenue [Line Items]        
Total operating revenues 2,166,969 2,141,527 3,712,428 3,506,252
Operating Segments | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 1,796,554 1,899,179 2,979,785 2,937,234
Alternative revenue program revenues 77,179 (20,117) 149,011 47,219
Other revenues 3,947 3,466 7,710 7,410
Total operating revenues 1,877,680 1,882,528 3,136,506 2,991,863
Operating Segments | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 322,131 270,773 642,164 539,466
Alternative revenue program revenues (32,842) (11,774) (66,242) (25,077)
Other revenues 0 0 0 0
Total operating revenues 289,289 258,999 575,922 514,389
Operating Segments | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 1,748,730 1,851,605 2,887,645 2,849,911
Operating Segments | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Transportation revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 44,363 43,352 85,841 80,079
Operating Segments | Transportation revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 318,780 266,514 636,183 532,543
Operating Segments | Miscellaneous revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 3,461 4,222 6,299 7,244
Operating Segments | Miscellaneous revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 3,351 4,259 5,981 6,923
Operating Segments | Residential | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 1,219,792 1,308,691 2,000,204 2,001,741
Operating Segments | Residential | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Commercial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 469,001 480,108 784,566 746,162
Operating Segments | Commercial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Industrial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 44,479 38,885 77,340 65,206
Operating Segments | Industrial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Public authority and other | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 15,458 23,921 25,535 36,802
Operating Segments | Public authority and other | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers $ 0 $ 0 $ 0 $ 0