Fair Value Measurements, Recurring (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets
Investments in AFS debt securities	$ 111	$ 221
Total gross fair value, assets	994	1,133
Effect of counterparty netting	(642)	(705)
Effect of cash collateral netting	(66)	(8)
Net carrying value on balance sheet, assets	286	420
Liabilities
Blending program obligations	58	55
Total gross fair value, liabilities	714	766
Effect of counterparty netting	(642)	(705)
Effect of cash collateral netting	(1)	0
Net carrying value on balance sheet, liabilities	71	61
Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	80	78
Commodity Contracts [Member]
Assets
Derivative contracts	803	830
Effect of counterparty netting	(642)	(705)
Effect of cash collateral netting	(66)	(8)
Derivative contracts, net assets	95	117
Cash collateral received not offset	0	0
Liabilities
Derivative contracts	643	705
Effect of counterparty netting	(642)	(705)
Effect of cash collateral netting	(1)	0
Derivative contracts, net liabilities	0	0
Cash collateral paid not offset	(67)	(149)
Physical Purchase Contracts [Member]
Assets
Derivative assets, not subject to netting		4
Liabilities
Derivative liabilities, not subject to netting	6	4
Foreign Currency Contracts [Member]
Liabilities
Derivative liabilities, not subject to netting	7	2
Fair Value, Inputs, Level 1 [Member]
Assets
Investments in AFS debt securities	36	56
Total gross fair value, assets	915	958
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	650	707
Fair Value, Inputs, Level 1 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	76	72
Fair Value, Inputs, Level 1 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	803	830
Liabilities
Derivative contracts	643	705
Fair Value, Inputs, Level 1 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative assets, not subject to netting		0
Liabilities
Derivative liabilities, not subject to netting	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative liabilities, not subject to netting	7	2
Fair Value, Inputs, Level 2 [Member]
Assets
Investments in AFS debt securities	75	165
Total gross fair value, assets	75	169
Liabilities
Blending program obligations	58	55
Total gross fair value, liabilities	64	59
Fair Value, Inputs, Level 2 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	0	0
Fair Value, Inputs, Level 2 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Fair Value, Inputs, Level 2 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative assets, not subject to netting		4
Liabilities
Derivative liabilities, not subject to netting	6	4
Fair Value, Inputs, Level 2 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative liabilities, not subject to netting	0	0
Fair Value, Inputs, Level 3 [Member]
Assets
Investments in AFS debt securities	0	0
Total gross fair value, assets	4	6
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	0	0
Fair Value, Inputs, Level 3 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	4	6
Fair Value, Inputs, Level 3 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Fair Value, Inputs, Level 3 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative assets, not subject to netting		0
Liabilities
Derivative liabilities, not subject to netting	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative liabilities, not subject to netting	$ 0	$ 0