Fair Value Measurements - Summary of Fair Value of Derivative Assets and Liabilities and Effect of Counterparty Netting (Details) - USD ($) $ in Millions | Mar. 31, 2021 | Dec. 31, 2020 |
Assets | | |
Total Fair Value of Gross Assets | $ 1,256 | $ 826 |
Effect of Counterparty Netting | (1,048) | (669) |
Effect of Collateral Netting | (8) | 0 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 200 | 157 |
Liabilities | | |
Total Fair Value Gross Liabilities | 17,680 | 18,265 |
Effect of Counterparty Netting | (1,048) | (669) |
Effect of Collateral Netting | (78) | (46) |
Difference in Carrying Value and Fair Value | (1,391) | (1,927) |
Net Carrying Value Presented on the Balance Sheet | 15,163 | 15,623 |
Level 1 | | |
Assets | | |
Total Fair Value of Gross Assets | 896 | 457 |
Liabilities | | |
Total Fair Value Gross Liabilities | 794 | 351 |
Level 2 | | |
Assets | | |
Total Fair Value of Gross Assets | 360 | 369 |
Liabilities | | |
Total Fair Value Gross Liabilities | 16,886 | 17,914 |
Level 3 | | |
Assets | | |
Total Fair Value of Gross Assets | 0 | 0 |
Liabilities | | |
Total Fair Value Gross Liabilities | 0 | 0 |
Commodity Derivative Assets | Exchange-cleared instruments | | |
Assets | | |
Commodity Derivative Assets | 1,083 | 670 |
Effect of Counterparty Netting | (1,048) | (669) |
Effect of Collateral Netting | (8) | 0 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 27 | 1 |
Liabilities | | |
Commodity Derivative Liabilities | 1,126 | 715 |
Effect of Counterparty Netting | (1,048) | (669) |
Effect of Collateral Netting | (78) | (46) |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 0 | 0 |
Commodity Derivative Assets | OTC instruments | | |
Liabilities | | |
Commodity Derivative Liabilities | 1 | |
Effect of Counterparty Netting | 0 | |
Effect of Collateral Netting | 0 | |
Difference in Carrying Value and Fair Value | 0 | |
Net Carrying Value Presented on the Balance Sheet | 1 | |
Commodity Derivative Assets | Physical forward contracts | | |
Assets | | |
Commodity Derivative Assets | 23 | 13 |
Effect of Counterparty Netting | 0 | 0 |
Effect of Collateral Netting | 0 | 0 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 23 | 13 |
Liabilities | | |
Commodity Derivative Liabilities | 13 | 10 |
Effect of Counterparty Netting | 0 | 0 |
Effect of Collateral Netting | 0 | 0 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 13 | 10 |
Commodity Derivative Assets | Level 1 | Exchange-cleared instruments | | |
Assets | | |
Commodity Derivative Assets | 746 | 314 |
Liabilities | | |
Commodity Derivative Liabilities | 794 | 351 |
Commodity Derivative Assets | Level 1 | OTC instruments | | |
Liabilities | | |
Commodity Derivative Liabilities | 0 | |
Commodity Derivative Assets | Level 1 | Physical forward contracts | | |
Assets | | |
Commodity Derivative Assets | 0 | 0 |
Liabilities | | |
Commodity Derivative Liabilities | 0 | 0 |
Commodity Derivative Assets | Level 2 | Exchange-cleared instruments | | |
Assets | | |
Commodity Derivative Assets | 337 | 356 |
Liabilities | | |
Commodity Derivative Liabilities | 332 | 364 |
Commodity Derivative Assets | Level 2 | OTC instruments | | |
Liabilities | | |
Commodity Derivative Liabilities | 1 | |
Commodity Derivative Assets | Level 2 | Physical forward contracts | | |
Assets | | |
Commodity Derivative Assets | 23 | 13 |
Liabilities | | |
Commodity Derivative Liabilities | 13 | 10 |
Commodity Derivative Assets | Level 3 | Exchange-cleared instruments | | |
Assets | | |
Commodity Derivative Assets | 0 | 0 |
Liabilities | | |
Commodity Derivative Liabilities | 0 | 0 |
Commodity Derivative Assets | Level 3 | OTC instruments | | |
Liabilities | | |
Commodity Derivative Liabilities | 0 | |
Commodity Derivative Assets | Level 3 | Physical forward contracts | | |
Assets | | |
Commodity Derivative Assets | 0 | 0 |
Liabilities | | |
Commodity Derivative Liabilities | 0 | 0 |
Interest rate derivatives | | |
Liabilities | | |
Commodity Derivative Liabilities | | 3 |
Interest-rate derivatives | 1 | |
Effect of Counterparty Netting | 0 | 0 |
Effect of Collateral Netting | 0 | 0 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Net Carrying Value Presented on the Balance Sheet | 1 | 3 |
Interest rate derivatives | Level 1 | | |
Liabilities | | |
Commodity Derivative Liabilities | | 0 |
Interest-rate derivatives | 0 | |
Interest rate derivatives | Level 2 | | |
Liabilities | | |
Commodity Derivative Liabilities | | 3 |
Interest-rate derivatives | 1 | |
Interest rate derivatives | Level 3 | | |
Liabilities | | |
Commodity Derivative Liabilities | | 0 |
Interest-rate derivatives | 0 | |
Rabbi trust assets | | |
Assets | | |
Rabbi trust assets | 150 | 143 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Rabbi trust assets | Level 1 | | |
Assets | | |
Rabbi trust assets | 150 | 143 |
Rabbi trust assets | Level 2 | | |
Assets | | |
Rabbi trust assets | 0 | 0 |
Rabbi trust assets | Level 3 | | |
Assets | | |
Rabbi trust assets | 0 | 0 |
Floating-rate debt | | |
Liabilities | | |
Debt | 1,475 | 1,940 |
Difference in Carrying Value and Fair Value | 0 | 0 |
Floating-rate debt | Net Carrying Value Presented on the Balance Sheet | | |
Liabilities | | |
Debt | 1,475 | 1,940 |
Floating-rate debt | Level 1 | | |
Liabilities | | |
Debt | 0 | 0 |
Floating-rate debt | Level 2 | | |
Liabilities | | |
Debt | 1,475 | 1,940 |
Floating-rate debt | Level 3 | | |
Liabilities | | |
Debt | 0 | 0 |
Fixed-rate debt, excluding finance leases | | |
Liabilities | | |
Debt | 15,064 | 15,597 |
Difference in Carrying Value and Fair Value | (1,391) | (1,927) |
Fixed-rate debt, excluding finance leases | Net Carrying Value Presented on the Balance Sheet | | |
Liabilities | | |
Debt | 13,673 | 13,670 |
Fixed-rate debt, excluding finance leases | Level 1 | | |
Liabilities | | |
Debt | 0 | 0 |
Fixed-rate debt, excluding finance leases | Level 2 | | |
Liabilities | | |
Debt | 15,064 | 15,597 |
Fixed-rate debt, excluding finance leases | Level 3 | | |
Liabilities | | |
Debt | $ 0 | $ 0 |