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Fair Value Measurements - Schedule of Assets and Liabilities Measured On Recurring Basis (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Fair Value, Measurements, Recurring |  |
Assets |  |
Equity securities | $ 541 | $ 510
Investments, including money market funds | 31 | 32
Interest rate derivatives | 0 | 1
Total assets | 572 | 554
Liabilities |  |
Total liabilities | 617 | 578
Fair Value, Measurements, Recurring | Indexed debt securities derivative |  |
Liabilities |  |
Derivative Liability | 605 | 578
Fair Value, Measurements, Recurring | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 11
Liabilities |  |
Derivative Liability | 12 | 0
Fair Value, Measurements, Recurring | Level 1 |  |
Assets |  |
Equity securities | 541 | 510
Investments, including money market funds | 31 | 32
Interest rate derivatives | 0 | 0
Total assets | 572 | 542
Liabilities |  |
Total liabilities | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Indexed debt securities derivative |  |
Liabilities |  |
Derivative Liability | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 0
Liabilities |  |
Derivative Liability | 0 | 0
Fair Value, Measurements, Recurring | Level 2 |  |
Assets |  |
Equity securities | 0 | 0
Investments, including money market funds | 0 | 0
Interest rate derivatives | 0 | 1
Total assets | 0 | 12
Liabilities |  |
Total liabilities | 617 | 578
Fair Value, Measurements, Recurring | Level 2 | Indexed debt securities derivative |  |
Liabilities |  |
Derivative Liability | 605 | 578
Fair Value, Measurements, Recurring | Level 2 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 11
Liabilities |  |
Derivative Liability | 12 | 0
Fair Value, Measurements, Recurring | Level 3 |  |
Assets |  |
Equity securities | 0 | 0
Investments, including money market funds | 0 | 0
Interest rate derivatives | 0 | 0
Total assets | 0 | 0
Liabilities |  |
Total liabilities | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Indexed debt securities derivative |  |
Liabilities |  |
Derivative Liability | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 0
Liabilities |  |
Derivative Liability | 0 | 0
Houston Electric | Fair Value, Measurements, Recurring |  |
Assets |  |
Investments, including money market funds | 14 | 17
Total assets | 14 | 17
Houston Electric | Fair Value, Measurements, Recurring | Level 1 |  |
Assets |  |
Investments, including money market funds | 14 | 17
Total assets | 14 | 17
Houston Electric | Fair Value, Measurements, Recurring | Level 2 |  |
Assets |  |
Investments, including money market funds | 0 | 0
Total assets | 0 | 0
Houston Electric | Fair Value, Measurements, Recurring | Level 3 |  |
Assets |  |
Investments, including money market funds | 0 | 0
Total assets | 0 | 0
CERC Corp |  |
Liabilities |  |
Total liabilities | 11 | 0
CERC Corp | Level 1 |  |
Liabilities |  |
Total liabilities | 0 | 0
CERC Corp | Level 2 |  |
Liabilities |  |
Total liabilities | 11 | 0
CERC Corp | Level 3 |  |
Liabilities |  |
Total liabilities | 0 | 0
CERC Corp | Fair Value, Measurements, Recurring |  |
Assets |  |
Investments, including money market funds | 15 | 14
Total assets | 15 | 23
CERC Corp | Fair Value, Measurements, Recurring | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 9
Liabilities |  |
Derivative Liability | 11 | 0
CERC Corp | Fair Value, Measurements, Recurring | Level 1 |  |
Assets |  |
Investments, including money market funds | 15 | 14
Total assets | 15 | 14
CERC Corp | Fair Value, Measurements, Recurring | Level 1 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 0
Liabilities |  |
Derivative Liability | 0 | 0
CERC Corp | Fair Value, Measurements, Recurring | Level 2 |  |
Assets |  |
Investments, including money market funds | 0 | 0
Total assets | 0 | 9
CERC Corp | Fair Value, Measurements, Recurring | Level 2 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 9
Liabilities |  |
Derivative Liability | 11 | 0
CERC Corp | Fair Value, Measurements, Recurring | Level 3 |  |
Assets |  |
Investments, including money market funds | 0 | 0
Total assets | 0 | 0
CERC Corp | Fair Value, Measurements, Recurring | Level 3 | Natural gas derivatives |  |
Assets |  |
Natural gas derivatives | 0 | 0
Liabilities |  |
Derivative Liability | $ 0 | $ 0

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