Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Sep. 30, 2024
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 22,962,043	$ 22,204,367
Total assets	26,497,093	25,194,465
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	16,942,174	16,372,659
Total assets	25,623,410	24,328,877
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	6,019,869	5,831,708
Total assets	6,341,439	6,181,558
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (5,467,756)	$ (5,315,970)