Fair Value Measurements, Recurring (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Assets
Investments in AFS debt securities	$ 224	$ 221
Total gross fair value, assets	919	1,133
Effect of counterparty netting	(425)	(705)
Effect of cash collateral netting	(74)	(8)
Net carrying value on Balance Sheet, assets	420	420
Liabilities
Blending program obligations	46	55
Total gross fair value, liabilities	485	766
Effect of counterparty netting	(425)	(705)
Effect of cash collateral netting	0	0
Net carrying value on Balance Sheet, liabilities	60	61
Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	98	125
Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	126	96
Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	77	78
Commodity Contracts [Member]
Assets
Derivative contracts	616	830
Effect of counterparty netting	(425)	(705)
Effect of cash collateral netting	(74)	(8)
Derivative contracts, net assets	117	117
Cash collateral received not offset	0	0
Liabilities
Derivative contracts	425	705
Effect of counterparty netting	(425)	(705)
Effect of cash collateral netting	0	0
Derivative contracts, net liabilities	0	0
Cash collateral paid not offset	(1)	(149)
Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	2	4
Liabilities
Derivative contracts, not subject to netting	5	4
Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	9	2
Fair Value, Inputs, Level 1 [Member]
Assets
Investments in AFS debt securities	85	56
Total gross fair value, assets	772	958
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	434	707
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	7	0
Fair Value, Inputs, Level 1 [Member] | Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	78	56
Fair Value, Inputs, Level 1 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	71	72
Fair Value, Inputs, Level 1 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	616	830
Liabilities
Derivative contracts	425	705
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, Inputs, Level 1 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	9	2
Fair Value, Inputs, Level 2 [Member]
Assets
Investments in AFS debt securities	139	165
Total gross fair value, assets	141	169
Liabilities
Blending program obligations	46	55
Total gross fair value, liabilities	51	59
Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Assets
Investments in AFS debt securities	91	125
Fair Value, Inputs, Level 2 [Member] | Prepaid Expenses and Other [Member]
Assets
Investments in AFS debt securities	48	40
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 contracts, not subject to netting	2	4
Liabilities
Derivative contracts, not subject to netting	5	4
Fair Value, Inputs, Level 2 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, 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	6	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	6	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 contracts, not subject to netting	0	0
Liabilities
Derivative contracts, not subject to netting	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Currency Contracts [Member]
Liabilities
Derivative contracts, not subject to netting	$ 0	$ 0