Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Edison International is the parent holding company of Southern California Edison Company ("SCE") and Edison Energy Group, Inc. ("Edison Energy Group"). SCE is an investor-owned public utility primarily engaged in the business of supplying and delivering electricity to an approximately 50,000 square mile area of southern California. Edison Energy Group is a holding company for subsidiaries, including Edison Energy, LLC ("Edison Energy"), engaged in pursuing competitive business opportunities across energy services and managed portfolio solutions for commercial and industrial customers. Such business activities are currently not material to report as a separate business segment. These combined notes to the consolidated financial statements apply to both Edison International and SCE unless otherwise described. Edison International's consolidated financial statements include the accounts of Edison International, SCE, and other wholly owned and controlled subsidiaries. References to Edison International refer to the consolidated group of Edison International and its subsidiaries. References to Edison International Parent and Other refer to Edison International Parent and its competitive subsidiaries. SCE's consolidated financial statements include the accounts of SCE and its wholly owned and controlled subsidiaries. All intercompany transactions have been eliminated from the consolidated financial statements. Edison International's and SCE's significant accounting policies were described in Note 1 of "Notes to Consolidated Financial Statements" included in Edison International's and SCE's combined Annual Report on Form 10-K for the year-ended December 31, 2017 (the "2017 Form 10-K"). This quarterly report should be read in conjunction with the financial statements and notes included in the 2017 Form 10-K. In the opinion of management, all adjustments, consisting of recurring accruals, have been made that are necessary to fairly state the consolidated financial position, results of operations, and cash flows in accordance with accounting principles generally accepted in the United States ("GAAP") for the periods covered by this quarterly report on Form 10-Q. The results of operations for the three-month period ended March 31, 2018 are not necessarily indicative of the operating results for the full year. The December 31, 2017 financial statement data was derived from audited financial statements, but does not include all disclosures required by GAAP.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash equivalents includes investments in money market funds. Generally, the carrying value of cash equivalents equals the fair value, as these investments have original maturities of three months or less.
Revenue Recognition	Revenue Recognition During the first three months of 2018, pending the outcome of the 2018 GRC decision, SCE recognized GRC-related revenue based on the 2017 authorized revenue requirement, adjusted for the July 2017 cost of capital decision and the impact of Tax Reform. The amounts billed to customers for the first three months of 2018 was also based on the 2017 authorized revenue requirement and a regulatory liability has been established to record any associated adjustments. The CPUC has authorized the establishment of a GRC memorandum account, which will make the 2018 revenue requirement ultimately adopted by the CPUC effective as of January 1, 2018. SCE cannot predict the revenue requirement the CPUC will authorize or provide assurance on the timing of a final decision. In December 2017, the FERC issued an order setting the effective date of SCE's new FERC formula rate as January 1, 2018, subject to settlement procedures and refund. Pending resolution of the FERC formula rate proceeding, SCE is recognizing revenue based on the FERC formula rate adjusted for the impact of Tax Reform and other adjustments.
Earnings Per Share	Earnings Per Share Edison International computes earnings per common share ("EPS") using the two-class method, which is an earnings allocation formula that determines EPS for each class of common stock and participating security. Edison International's participating securities are stock-based compensation awards payable in common shares, including restricted stock units, which earn dividend equivalents on an equal basis with common shares once the awards are vested.
New Accounting Guidance	New Accounting Guidance Accounting Guidance Adopted In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on revenue recognition and further amended the standard in 2016 and 2017. Under the new standard, revenue is recognized when a good or service is transferred to the customer and the customer obtains control of the good or service. Some revenue arrangements, such as alternative revenue programs which include balancing account overcollections and undercollections, are excluded from the scope of the new standard and, therefore, will be accounted for and presented separately from revenue recognized from contracts with customers in the disclosures. Edison International and SCE adopted this standard effective January 1, 2018, using the modified retrospective method for contracts that were not completed as of the adoption date. Edison International recognized a cumulative effect adjustment to increase the opening balance of retained earnings by approximately $5 million ($7 million pre-tax) on January 1, 2018. This adjustment is related to variable consideration recognized at Edison Energy which is not subject to potential significant reversal and has no further performance obligations. See Note 7 for further details. In January 2016, the FASB issued an accounting standards update that amends the guidance on the classification and measurement of financial instruments, and further amended the guidance in 2018. Under the new guidance, equity investments (excluding those accounted for under the equity method or those that result in consolidation) are required to be measured at fair value, with changes in fair value recognized in net income. The new guidance also amends certain disclosure requirements associated with the fair value of financial instruments and requires financial assets and financial liabilities to be presented separately in the notes to the financial statements, grouped by measurement category and form of financial assets. Edison International and SCE adopted this guidance effective January 1, 2018. Edison International recognized a cumulative effect adjustment to increase the opening balance of retained earnings and accumulated other comprehensive loss by $5 million ($8 million pre-tax) on January 1, 2018. See Note 2 for further details. The FASB issued two accounting standards updates related to the statement of cash flows. One standard update clarifies the presentation and classification of certain cash receipts and payments in the statement of cash flows and other requires restricted cash to be presented with cash and cash equivalents in the statement of cash flows. Edison International and SCE adopted these standards effective January 1, 2018, using the retrospective approach. The adoption of these standards did not have a material impact on Edison International's and SCE's consolidated statement of cash flows. In March 2017, the FASB issued an accounting standards update on the presentation of the components of net periodic benefit cost for an entity's defined benefit pension and other postretirement plans. Edison International and SCE adopted this guidance effective January 1, 2018. The adoption of this standard did not have a material impact on Edison International's and SCE's consolidated financial statements, but did result in the separate presentation of service costs as an operating expense and non-service costs within other income and expenses and limits the capitalization of benefit costs to the service cost component. The standard was adopted retrospectively with respect to the income statement presentation requirement and prospectively for the capitalization requirement. During the three months ended March 31, 2017, non-service costs (benefits) totaled $(8) million and $(9) million for Edison International and SCE, respectively, which were reclassified from "Operation and maintenance" to "Other income and expenses." See Note 9 and Note 14 for further details. Accounting Guidance Not Yet Adopted In February 2016, the FASB issued an accounting standards update related to lease accounting and further amended the standard in 2018. The updated standard is effective January 1, 2019. Under the new standard, a lease is defined as a contract, or part of a contract, that conveys the right to control the use of identified assets for a period of time in exchange for consideration. Lessees will need to recognize leases on the balance sheet as a right-of-use asset and a related lease liability, and classify the leases as either operating or finance. The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustments, such as initial direct costs. Edison International's operating leases will result in straight-line expense while finance leases will result in a higher initial expense pattern due to the interest component. SCE, as a regulated entity, is permitted to continue to recognize expense using the timing that conforms to the regulatory rate treatment. Lessees can elect to exclude from the balance sheet short-term contracts of one year or less. This standard requires retrospective application to previously issued financial statements for 2018 and 2017. Although permitted, Edison International and SCE has elected not to adopt this standard prior to January 1, 2019. The standard will provide entities with an optional transition method to apply the new requirements in the period of adoption without retrospective application to previous periods. Edison International and SCE are evaluating whether to elect this optional transition method. The adoption of this standard will increase right-of-use assets and lease liabilities in Edison International's and SCE's consolidated balance sheets. Edison International and SCE are currently implementing a new lease accounting system and are evaluating the impact this standard will have on the consolidated balance sheets and lease disclosures. The FASB issued an accounting standards update related to the impairment of financial instruments, effective January 1, 2020. The new guidance provides an impairment model, known as the current expected credit loss model, which is based on expected credit losses rather than incurred losses. Edison International and SCE are currently evaluating the impact of this new guidance. In January 2017, the FASB issued an accounting standards update to simplify the accounting for goodwill impairment. This accounting standards update changes the procedural steps in applying the goodwill impairment test. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Edison International will apply this guidance to the goodwill impairment test beginning in 2020. In February 2018, the FASB issued an accounting standards update related to stranded income tax effects due to the 2017 Tax Reform enacted on December 22, 2017. As a result of the lower federal corporate tax rate, deferred taxes were re-measured with the impact included in operating income in December 2017. The tax effects of items within AOCI were appropriately left unadjusted (i.e. stranded tax effects) and, therefore, are not stated at the revised tax rate. The new accounting guidance provides entities with an election to reclassify from AOCI to retained earnings for stranded income tax effects resulting from the 2017 Tax Reform. The new guidance should be applied either in the period of adoption or retrospectively to each period(s) in which the effect of the rate change is recognized. The new guidance is effective January 1, 2019 with early adoption permitted. Edison International and SCE are in the process of evaluating the new guidance.