Fair Value Measurements - Nonrecurring Fair Value Measures Within Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025		Sep. 30, 2024		Sep. 30, 2023	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Impairment of Assets	$ 141,802	[1]	$ 519,129	[1]	$ 0
Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Impairment of Assets	33,453		55,437		0
Level 3 | Fair Value, Nonrecurring | Integrated Upstream and Gathering | December 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Property, plant, and equipment, fair value						$ 12,880
Impairment of Assets	33,453		0		0
Level 3 | Fair Value, Nonrecurring | Integrated Upstream and Gathering | September 30, 2024
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Property, plant, and equipment, fair value			3,000
Impairment of Assets	0		9,362		0
Level 3 | Fair Value, Nonrecurring | Pipeline and Storage
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value			12,133
Impairment of Assets	$ 0		$ 46,075		$ 0

[1] The Company considers this line to be a significant expense.