Fair Value Measurements, Recurring (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Assets
Investments in AFS debt securities	$ 26	$ 26
Total gross fair value, assets	622	529
Effect of counterparty netting	(447)	(402)
Effect of cash collateral netting	(25)	0
Net carrying value on balance sheet, assets	150	127
Liabilities
Blending program obligations	113	13
Total gross fair value, liabilities	597	464
Effect of counterparty netting	(447)	(402)
Effect of cash collateral netting	(25)	(46)
Net carrying value on balance sheet, liabilities	125	16
Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	89	93
Commodity Contracts [Member]
Assets
Derivative contracts	506	402
Effect of counterparty netting	(447)	(402)
Effect of cash collateral netting	(25)	0
Derivative contracts, net assets	34	0
Cash collateral received not offset	0	0
Liabilities
Derivative contracts	472	448
Effect of counterparty netting	(447)	(402)
Effect of cash collateral netting	(25)	(46)
Derivative contracts, net liabilities	0	0
Cash collateral paid not offset	(99)	(71)
Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	1	2
Liabilities
Derivative contracts, not subject to netting	12	3
Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		6
Level 1 [Member]
Assets
Investments in AFS debt securities	0	6
Total gross fair value, assets	591	503
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	472	448
Level 1 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	85	89
Level 1 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	506	402
Liabilities
Derivative contracts	472	448
Level 1 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	0
Liabilities
Derivative contracts, not subject to netting	0	0
Level 1 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		6
Level 2 [Member]
Assets
Investments in AFS debt securities	26	20
Total gross fair value, assets	27	22
Liabilities
Blending program obligations	113	13
Total gross fair value, liabilities	125	16
Level 2 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	0	0
Level 2 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Level 2 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	1	2
Liabilities
Derivative contracts, not subject to netting	12	3
Level 2 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		0
Level 3 [Member]
Assets
Investments in AFS debt securities	0	0
Total gross fair value, assets	4	4
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	0	0
Level 3 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	4	4
Level 3 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Level 3 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	0
Liabilities
Derivative contracts, not subject to netting	$ 0	0
Level 3 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		$ 0