Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 23,632,223	$ 22,204,367
Total assets	26,980,381	25,194,465
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	17,422,364	16,372,659
Total assets	26,109,156	24,328,877
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	6,209,859	5,831,708
Total assets	6,541,506	6,181,558
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (5,670,281)	$ (5,315,970)