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Investments | 12 Months Ended
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Dec. 31, 2020
Regulated Entity, Other Assets, Noncurrent [Abstract] |
Investments | Investments Nuclear Decommissioning Trusts Future decommissioning costs related to SCE's nuclear assets are expected to be funded from independent decommissioning trusts. The following table sets forth amortized cost and fair value of the trust investments (see Note 4 for a discussion of fair value of the trust investments):
| Longest Maturity Date |  | Amortized Cost |  | Fair Value
|  | December 31,
(in millions) |  | 2020 |  | 2019 |  | 2020 |  | 2019
Stocks | — |  | N/A |  | N/A |  | $ | 1,908 |  |  | $ | 1,765 |
Municipal bonds | 2057 |  | 1,013 |  |  | 822 |  |  | 1,218 |  |  | 970 |
U.S. government and agency securities | 2067 |  | 740 |  |  | 996 |  |  | 864 |  |  | 1,115 |
Corporate bonds | 2070 |  | 460 |  |  | 597 |  |  | 550 |  |  | 679 |
Short-term investments and receivables/payables 1 | One-year |  | 281 |  |  | 32 |  |  | 293 |  |  | 33 |
Total |  |  | $ | 2,494 |  |  | $ | 2,447 |  |  | $ | 4,833 |  |  | $ | 4,562 |
1 Short-term investments include $138 million and $41 million of repurchase agreements payable by financial institutions which earn interest, are fully secured by U.S. Treasury securities and mature by January 4, 2021 and January 2, 2020 as of December 31, 2020 and 2019, respectively. Trust fund earnings (based on specific identification) increase the trust fund balance and the ARO regulatory liability. Unrealized holding gains, net of losses, were $2.1 billion and $1.8 billion at December 31, 2020 and 2019, respectively. Trust assets are used to pay income taxes. Deferred tax liabilities related to net unrealized gains were $515 million and $449 million at December 31, 2020 and December 31, 2019, respectively. Accordingly, the fair value of trust assets available to pay future decommissioning costs, net of deferred income taxes, totaled $4.3 billion and $4.1 billion at December 31, 2020 and December 31, 2019, respectively. The following table summarizes the gains and losses for the trust investments:
| December 31,
(in millions) | 2020 | 2019 | 2018
Gross realized gains | $ | 255 |  | $ | 87 |  | $ | 134 |
Gross realized losses | (6) |  | (2) |  | (27) |
Net unrealized gains (losses) for equity securities | 176 |  | 343 |  | (233) |
Due to regulatory mechanisms, changes in assets of the trusts from income or loss items have no impact on operating revenue or earnings.

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