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Nuclear Decommissioning Trust Fund - Summary of Aggregate Fair Values and Realized Gains and Losses (Details) - USD ($) $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2023 | Dec. 31, 2022
Nuclear decommissioning trust fund |  |
Fair Value | $ 0 | $ 838
Unrealized Gains |  | 346
Unrealized Losses |  | 36
Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | 922 |
Unrealized Gains | 409 |
Unrealized Losses | 27 |
Cash and cash equivalents |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | 15
Unrealized Gains |  | 0
Unrealized Losses |  | 0
Cash and cash equivalents | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | 21 |
Unrealized Gains | 0 |
Unrealized Losses | $ 0 |
U.S. government and federal agency obligations |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | 86
Unrealized Gains |  | 0
Unrealized Losses |  | $ 5
Weighted-average Maturities (In years) | 12 years | 11 years
U.S. government and federal agency obligations | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | $ 90 |
Unrealized Gains | 1 |
Unrealized Losses | $ 5 |
Federal agency mortgage-backed securities |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | $ 101
Unrealized Gains |  | 0
Unrealized Losses |  | $ 11
Weighted-average Maturities (In years) | 25 years | 26 years
Federal agency mortgage-backed securities | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | $ 103 |
Unrealized Gains | 0 |
Unrealized Losses | $ 8 |
Commercial mortgage-backed securities |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | $ 35
Unrealized Gains |  | 0
Unrealized Losses |  | $ 4
Weighted-average Maturities (In years) | 29 years | 30 years
Commercial mortgage-backed securities | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | $ 34 |
Unrealized Gains | 0 |
Unrealized Losses | $ 4 |
Corporate debt securities |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | $ 114
Unrealized Gains |  | 0
Unrealized Losses |  | $ 13
Weighted-average Maturities (In years) | 12 years | 12 years
Corporate debt securities | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | $ 116 |
Unrealized Gains | 0 |
Unrealized Losses | 10 |
Equity securities |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | $ 486
Unrealized Gains |  | 346
Unrealized Losses |  | 3
Equity securities | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | 557 |
Unrealized Gains | 408 |
Unrealized Losses | $ 0 |
Foreign government fixed income securities |  |
Nuclear decommissioning trust fund |  |
Fair Value |  | 1
Unrealized Gains |  | 0
Unrealized Losses |  | $ 0
Weighted-average Maturities (In years) | 20 years | 17 years
Foreign government fixed income securities | Held-for-sale |  |
Nuclear decommissioning trust fund |  |
Fair Value | $ 1 |
Unrealized Gains | 0 |
Unrealized Losses | $ 0 |

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 + Details
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- Definition The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 + Details
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