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Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value | $ 4,440 | $ 4,242
SCE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value | 4,440 | 4,242
SCE | Fair Value, Measurements, Recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 2,803 | 2,784
Fair Value | 4,499 | 4,369
Total Fair Value | 4,440 | 4,242
SCE | Fair Value, Measurements, Recurring | Stocks |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 236 | 319
Fair Value | 1,596 | 1,547
SCE | Fair Value, Measurements, Recurring | Municipal bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 643 | 659
Fair Value | 768 | 766
SCE | Fair Value, Measurements, Recurring | U.S. government and agency securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 1,235 | 1,131
Fair Value | 1,319 | 1,191
SCE | Fair Value, Measurements, Recurring | Corporate bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 579 | 600
Fair Value | 643 | 659
SCE | Fair Value, Measurements, Recurring | Short-term investments and receivables/payables |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Amortized Cost | 110 | 75
Fair Value | 114 | 79
Repurchase agreements payable | $ 29 | $ 114

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- Definition The amount of decommissioning trust assets at amortized cost as of the balance sheet date. + References No definition available. + Details
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- Definition Decommissioning Trust Investments + References No definition available. + 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/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition The carrying value of securities purchased to be resold in reverse repurchase transactions as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(m)(2)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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