Fair Value Measurements - PAC (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, offset	$ (31)	$ (194)
Assets, fair value	6,188	8,824
Derivative liability, offset	58	107
Cash collateral receivable (payable)	27	(87)
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	5,523	7,742
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	685	1,217
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	11	59
Commodity derivatives | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, offset	(31)	(194)
Derivative assets	95	477
Derivative liability, offset	54	106
Derivative liability	(182)	(218)
Commodity derivatives | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	1	6
Derivative liability, not subject to master netting arrangement	7	8
Commodity derivatives | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	121	614
Derivative liability, not subject to master netting arrangement	134	206
Commodity derivatives | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	4	51
Derivative liability, not subject to master netting arrangement	95	110
PAC | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	219	871
PAC | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	201	672
PAC | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	32	318
PAC | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
PAC | Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash collateral receivable (payable)	10	(78)
Cash collateral payable, not offset		12
PAC | Commodity derivatives | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, offset	(14)	(119)
Derivative assets	18	199
Derivative liability, offset	24	41
Derivative liability	(84)	(7)
Cash collateral receivable (payable)	10	(78)
Cash collateral payable, not offset		12
PAC | Commodity derivatives | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	0	0
Derivative liability, not subject to master netting arrangement	0	0
PAC | Commodity derivatives | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	32	318
Derivative liability, not subject to master netting arrangement	108	48
PAC | Commodity derivatives | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, not subject to master netting arrangement	0	0
Derivative liability, not subject to master netting arrangement	0	0
PAC | Money market mutual funds | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	175	649
PAC | Money market mutual funds | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	175	649
PAC | Money market mutual funds | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	0	0
PAC | Money market mutual funds | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	0	0
PAC | Investment funds | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	26	23
PAC | Investment funds | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	26	23
PAC | Investment funds | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	0	0
PAC | Investment funds | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment funds	$ 0	$ 0