Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Sep. 30, 2025
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 26,267,871	$ 25,292,990
Total assets	29,798,395	28,249,522
Operating Segments
Segment Reporting Information [Line Items]
Net property, plant and equipment	26,267,871	25,292,990
Total assets	35,956,665	34,193,451
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	19,503,317	18,765,128
Total assets	28,804,007	27,296,805
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	6,764,554	6,527,862
Total assets	7,152,658	6,896,646
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total assets	$ (6,158,270)	$ (5,943,929)