Acquisitions - Narrative (Details) $ in Millions				1 Months Ended				3 Months Ended		9 Months Ended
	Nov. 01, 2025 USD ($)	Oct. 31, 2025 USD ($)	Jan. 31, 2025 USD ($)	Jul. 31, 2025 USD ($)	Feb. 28, 2025 USD ($)	Jan. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)
Business Combination [Line Items]
Gain on investments in unconsolidated entities, net										$ 31	$ 0
Cheyenne Pipeline LLC
Business Combination [Line Items]
Ownership interest in unconsolidated entity, prior to acquisition (as a percent)					50.00%
BridgeTex Pipeline Company, LLC
Business Combination [Line Items]
Ownership interest in unconsolidated entity, prior to acquisition (as a percent)				40.00%
Permian JV
Business Combination [Line Items]
Ownership interest in the Permian JV (as a percent)						65.00%			65.00%
Ironwood Midstream Energy Partners II, LLC
Business Combination [Line Items]
Finite-lived intangible asset, useful life			16 years			16 years
Ironwood Midstream Energy Partners II, LLC | Customer Relationships
Business Combination [Line Items]
Finite-lived intangible asset, useful life								16 years		16 years
Amortization								$ 1		$ 3
Ironwood Midstream Energy Partners II, LLC | Finite-Lived Intangible Assets | Level 3 | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow
Business Combination [Line Items]
Business combination, measurement input			0.18
EMG Medallion 2 Holdings
Business Combination [Line Items]
Acquisition amount, net to our interest						$ 106
Other payments to acquire businesses							$ 16
Cheyenne Pipeline LLC
Business Combination [Line Items]
Ownership interests acquired percentage (as a percent)					50.00%
Gain on investments in unconsolidated entities, net					$ 31
Black Knight Midstream, LLC
Business Combination [Line Items]
Acquisition amount									$ 59
Acquisition amount, net to our interest									$ 38
BridgeTex Pipeline Company, LLC
Business Combination [Line Items]
Acquisition amount				$ 180
Ownership interests acquired percentage (as a percent)				20.00%
EPIC Crude Oil Pipeline | Subsequent Event
Business Combination [Line Items]
Ownership interests acquired percentage (as a percent)	45.00%	55.00%
Business combination, consideration transferred	$ 1,330	$ 1,570
Business combination, recognized liability assumed, long-term debt, noncurrent	500	600
Potential earnout payment	$ 157	$ 193
Business combination, achieved in stages, preacquisition and acquired equity interests in acquiree, percentage	100.00%
EnCap Flatrock Midstream | Ironwood Midstream Energy Partners II, LLC
Business Combination [Line Items]
Acquisition amount			$ 481
The Energy & Minerals Group | EMG Medallion 2 Holdings | Permian JV
Business Combination [Line Items]
Acquisition amount						$ 163