Summary of Significant Accounting Policies - Schedule of Depreciable Plant by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Depreciable plant	$ 13,998,897	$ 13,101,006
Exploration and Production
Segment Reporting Information [Line Items]
Depreciable plant	7,275,495	6,741,095
Pipeline and Storage
Segment Reporting Information [Line Items]
Depreciable plant	2,919,506	2,803,690
Gathering
Segment Reporting Information [Line Items]
Depreciable plant	1,142,000	1,032,969
Utility
Segment Reporting Information [Line Items]
Depreciable plant	2,645,981	2,507,465
All Other and Corporate
Segment Reporting Information [Line Items]
Depreciable plant	$ 15,915	$ 15,787