Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 20,814,563	$ 19,606,583
Total assets	24,004,640	22,516,968
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	15,346,551	14,402,578
Total assets	23,212,086	21,716,467
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	5,468,012	5,204,005
Total assets	5,776,113	5,504,972
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (4,983,559)	$ (4,704,471)