Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 24,378,143	$ 22,204,367
Total assets	27,712,527	25,194,465
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	18,010,431	16,372,659
Total assets	26,806,555	24,328,877
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	6,367,712	5,831,708
Total assets	6,705,835	6,181,558
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (5,799,863)	$ (5,315,970)