v3.26.1
Revenue from Contracts with Customers (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 Revenues from Contracts with Customers $ 909,034 $ 734,758 $ 1,546,898 $ 1,248,595
Alternative Revenue Programs (1,967) 3,026 (1,718) 8,943
Derivative Financial Instruments (48,694) (7,834) (35,299) 21,894
Total Revenues 858,373 729,950 1,509,881 1,279,432
Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 946,861 773,265 1,622,478 1,325,049
Alternative Revenue Programs (1,967) 3,026 (1,718) 8,943
Derivative Financial Instruments (48,694) (7,834) (35,299) 21,894
Total Revenues 896,200 768,457 1,585,461 1,355,886
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 (37,827) (38,507) (75,580) (76,454)
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues [1] (37,827) (38,507) (75,580) (76,454)
Integrated Upstream and Gathering        
Disaggregation of Revenue [Line Items]        
Total Revenues 358,823 315,191 682,045 567,499
Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 407,517 323,025 717,344 545,605
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments (48,694) (7,834) (35,299) 21,894
Total Revenues 358,823 315,191 682,045 567,499
Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Total Revenues 73,762 71,185 142,999 139,935
Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 111,463 109,573 218,364 216,186
Alternative Revenue Programs 0 0 0 0
Derivative Financial Instruments 0 0 0 0
Total Revenues 111,463 109,573 218,364 216,186
Utility        
Disaggregation of Revenue [Line Items]        
Total Revenues 425,788 343,574 684,837 571,998
Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 427,881 340,667 686,770 563,258
Alternative Revenue Programs (1,967) 3,026 (1,718) 8,943
Derivative Financial Instruments 0 0 0 0
Total Revenues 425,914 343,693 685,052 572,201
Production of Natural Gas        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 400,217 318,404 702,677 535,863
Production of Natural Gas | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 400,217 318,404 702,677 535,863
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 | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 400,217 318,404 702,677 535,863
Production of Natural Gas | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Natural Gas | Utility | Operating 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 439 393 731 907
Production of Crude Oil | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 439 393 731 907
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 | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 439 393 731 907
Production of Crude Oil | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Production of Crude Oil | Utility | Operating 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 200 338 364 613
Natural Gas Processing | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 200 338 364 613
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 | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 200 338 364 613
Natural Gas Processing | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Processing | Utility | Operating 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 2,624 3,233 5,390 6,681
Natural Gas Gathering Service | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,624 3,233 5,390 6,681
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 0 0 0 0
Natural Gas Gathering Service | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,624 3,233 5,390 6,681
Natural Gas Gathering Service | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Gathering Service | Utility | Operating 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 104,977 100,199 191,846 181,143
Natural Gas Transportation Service | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 131,626 127,737 245,252 235,862
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 (26,649) (27,538) (53,406) (54,719)
Natural Gas Transportation Service | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Transportation Service | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 83,048 82,481 164,056 163,686
Natural Gas Transportation Service | Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 48,578 45,256 81,196 72,176
Natural Gas Storage Service        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 14,786 14,597 29,208 29,086
Natural Gas Storage Service | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 25,677 25,288 50,814 50,281
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 (10,891) (10,691) (21,606) (21,195)
Natural Gas Storage Service | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Storage Service | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 25,677 25,288 50,814 50,281
Natural Gas Storage Service | Utility | Operating 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 322,969 257,100 520,978 413,450
Natural Gas Residential Sales | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 322,969 257,100 520,978 413,450
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 | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Residential Sales | Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 322,969 257,100 520,978 413,450
Natural Gas Commercial Sales        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 50,887 39,602 78,764 61,845
Natural Gas Commercial Sales | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 50,887 39,602 78,764 61,845
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 | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Commercial Sales | Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 50,887 39,602 78,764 61,845
Natural Gas Industrial Sales        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,555 1,935 3,964 3,272
Natural Gas Industrial Sales | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,558 1,937 3,967 3,275
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 (3) (2) (3) (3)
Natural Gas Industrial Sales | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 0 0 0 0
Natural Gas Industrial Sales | Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,558 1,937 3,967 3,275
Other        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 9,380 (1,043) 12,976 15,735
Other | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 9,664 (767) 13,541 16,272
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 (284) (276) (565) (537)
Other | Integrated Upstream and Gathering | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 4,037 657 8,182 1,541
Other | Pipeline and Storage | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers 2,738 1,804 3,494 2,219
Other | Utility | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total Revenues from Contracts with Customers $ 2,889 $ (3,228) $ 1,865 $ 12,512
[1] Corporate and All Other categories primarily represent other non-segment business activities and eliminating entries.