Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 21,422,118	$ 19,606,583
Total assets	24,891,251	22,516,968
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	15,855,074	14,402,578
Total assets	24,067,602	21,716,467
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	5,567,044	5,204,005
Total assets	5,901,759	5,504,972
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (5,078,110)	$ (4,704,471)