Summary of Significant Accounting Policies - Schedule of Depreciable Plant by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Depreciable plant	$ 13,101,006	$ 12,233,508
Exploration and Production
Segment Reporting Information [Line Items]
Depreciable plant	6,741,095	6,088,476
Pipeline and Storage
Segment Reporting Information [Line Items]
Depreciable plant	2,803,690	2,747,948
Gathering
Segment Reporting Information [Line Items]
Depreciable plant	1,032,969	971,665
Utility
Segment Reporting Information [Line Items]
Depreciable plant	2,507,465	2,411,707
All Other and Corporate
Segment Reporting Information [Line Items]
Depreciable plant	$ 15,787	$ 13,712