v3.25.2
Revenue from Contracts with Customers (Disaggregation of Revenue) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers $ 527,430 $ 338,644 $ 1,776,653 $ 1,397,392
Alternative Revenue Programs 1,885 3,336 10,200 19,949
Derivative Financial Instruments 2,515 75,462 24,409 155,401
Total Revenues 531,830 417,442 1,811,262 1,572,742
All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues 0 0 0 0
Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (103,028) (93,946) (298,962) (278,804)
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues (103,028) (93,946) (298,962) (278,804)
Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 301,368 145,443 840,292 584,136
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 2,515 75,462 24,409 155,401
Total Revenues 303,883 220,905 864,701 739,537
Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 105,579 105,419 321,765 307,852
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues 105,579 105,419 321,765 307,852
Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 67,873 60,120 194,034 186,701
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues 67,873 60,120 194,034 186,701
Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 155,638 121,608 719,524 597,507
Alternative Revenue Programs 1,885 3,336 10,200 19,949
Derivative Financial Instruments 0 0 0 0
Total Revenues 157,523 124,944 729,724 617,456
Production of Natural Gas        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 300,137 144,374 836,000 580,233
Production of Natural Gas | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Natural Gas | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Natural Gas | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 300,137 144,374 836,000 580,233
Production of Natural Gas | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Natural Gas | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Natural Gas | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 434 511 1,341 1,722
Production of Crude Oil | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 434 511 1,341 1,722
Production of Crude Oil | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 267 195 881 765
Natural Gas Processing | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 267 195 881 765
Natural Gas Processing | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Gathering Service        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,519 3,644 9,200 12,157
Natural Gas Gathering Service | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Gathering Service | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (65,354) (56,476) (184,834) (174,544)
Natural Gas Gathering Service | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Gathering Service | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Gathering Service | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 67,873 60,120 194,034 186,701
Natural Gas Gathering Service | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Transportation Service        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 75,029 74,504 256,172 248,309
Natural Gas Transportation Service | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Transportation Service | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (26,845) (26,826) (81,564) (73,040)
Natural Gas Transportation Service | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Transportation Service | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 80,235 79,640 243,921 232,532
Natural Gas Transportation Service | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Transportation Service | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 21,639 21,690 93,815 88,817
Natural Gas Storage Service        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 14,424 14,176 43,510 40,727
Natural Gas Storage Service | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Storage Service | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (10,604) (10,436) (31,799) (30,520)
Natural Gas Storage Service | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Storage Service | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 25,028 24,612 75,309 71,247
Natural Gas Storage Service | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Storage Service | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 118,551 89,034 532,001 445,971
Natural Gas Residential Sales | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 118,551 89,034 532,001 445,971
Natural Gas Commercial Sales        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 15,349 11,022 77,194 62,117
Natural Gas Commercial Sales | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 15,349 11,022 77,194 62,117
Natural Gas Industrial Sales        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 731 479 4,003 2,663
Natural Gas Industrial Sales | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (1) (1) (4) (5)
Natural Gas Industrial Sales | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 732 480 4,007 2,668
Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (11) 705 16,351 2,728
Other | All Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Other | Corporate and Intersegment Eliminations        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers (224) (207) (761) (695)
Other | Exploration and Production | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 530 363 2,070 1,416
Other | Pipeline and Storage | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 316 1,167 2,535 4,073
Other | Gathering | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Other | Utility | Total Reportable Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers $ (633) $ (618) $ 12,507 $ (2,066)