Fair Value Measurements, Recurring (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Assets
Investments in AFS debt securities			$ 0
Fair Value, Recurring [Member]
Assets
Investments in AFS debt securities	$ 202,000,000	$ 221,000,000
Total gross fair value, assets	749,000,000	1,133,000,000
Effect of counterparty netting	(398,000,000)	(705,000,000)
Effect of cash collateral netting	0	(8,000,000)
Net carrying value on Balance Sheet, assets	351,000,000	420,000,000
Liabilities
Blending program obligations	55,000,000	55,000,000
Total gross fair value, liabilities	505,000,000	766,000,000
Effect of counterparty netting	(398,000,000)	(705,000,000)
Effect of cash collateral netting	0	0
Net carrying value on Balance Sheet, liabilities	107,000,000	61,000,000
Fair Value, Recurring [Member] | Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	0	125,000,000
Fair Value, Recurring [Member] | Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	202,000,000	96,000,000
Fair Value, Recurring [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	78,000,000	78,000,000
Fair Value, Recurring [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	469,000,000	830,000,000
Effect of counterparty netting	(398,000,000)	(705,000,000)
Effect of cash collateral netting	0	(8,000,000)
Derivative contracts, net assets	71,000,000	117,000,000
Cash collateral received not offset	0	0
Liabilities
Derivative contracts	398,000,000	705,000,000
Effect of counterparty netting	(398,000,000)	(705,000,000)
Effect of cash collateral netting	0	0
Derivative contracts, net liabilities	0	0
Cash collateral paid not offset	(54,000,000)	(149,000,000)
Fair Value, Recurring [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	4,000,000
Liabilities
Derivative contracts, not subject to netting	51,000,000	4,000,000
Fair Value, Recurring [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	1,000,000	2,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Investments in AFS debt securities	104,000,000	56,000,000
Total gross fair value, assets	645,000,000	958,000,000
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	399,000,000	707,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	104,000,000	56,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	72,000,000	72,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	469,000,000	830,000,000
Liabilities
Derivative contracts	398,000,000	705,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, 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
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	1,000,000	2,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Investments in AFS debt securities	98,000,000	165,000,000
Total gross fair value, assets	98,000,000	169,000,000
Liabilities
Blending program obligations	55,000,000	55,000,000
Total gross fair value, liabilities	106,000,000	59,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	0	125,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	98,000,000	40,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	4,000,000
Liabilities
Derivative contracts, not subject to netting	51,000,000	4,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Investments in AFS debt securities	0	0
Total gross fair value, assets	6,000,000	6,000,000
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	6,000,000	6,000,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, 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
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	$ 0	$ 0