Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2017
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"). 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 International is also the parent company of Edison Energy Group, Inc., a holding company for subsidiaries engaged in pursuing competitive business opportunities across energy services, managed portfolio solutions, and distributed solar 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, 2016 (the "2016 Form 10-K"). This quarterly report should be read in conjunction with the financial statements and notes included in the 2016 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- and nine-month periods ended September 30, 2017 are not necessarily indicative of the operating results for the full year. The December 31, 2016 financial statement data was derived from audited financial statements, but does not include all disclosures required by GAAP.
Cash Equivalents	Cash Equivalents 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.
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 performance shares and 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 Not Yet 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 (or as) a good or service is transferred to the customer and the customer obtains control of the good or service. This standard will be adopted on January 1, 2018. Edison International and SCE have completed the evaluation of all significant revenue streams. Edison International and SCE do not believe the adoption of this standard will have a material impact on the financial position or results of operations. For the nine months ended September 30, 2017, approximately 95% of total operating revenue arises from SCE's tariff offerings that provide electricity to customers. For such arrangements, revenue from contracts with customers will be equivalent to the electricity supplied and billed in that period (including estimated billings). As such, there will not be a change in the timing or pattern of revenue recognition for such sales. Edison International and SCE are in the process of implementing the system and process changes necessary to comply with this standard's enhanced disclosure requirements. Edison International and SCE plan to disaggregate customer contract revenue between revenue from earnings activities and revenue from cost-recovery activities. Some revenue arrangements, such as alternative revenue programs which include balancing account over- and under-collections, are excluded from the scope of the new standard and, therefore, will be accounted for and presented separately from revenues recognized under the new standard on the Edison International and SCE consolidated financial statements. Edison International and SCE will adopt the standard by using the modified retrospective method by recognizing a cumulative effect adjustment to the opening balance of retained earnings on January 1, 2018. Edison International and SCE do not expect the cumulative effect adjustment to be material. In January 2016, the FASB issued an accounting standards update that amends the guidance on the classification and measurement of financial instruments. The amendments require equity investments (excluding those accounted for under the equity method or those that result in consolidation) to be measured at fair value, with changes in fair value recognized in net income. It also amends certain disclosure requirements associated with the fair value of financial instruments. In addition, the new guidance 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 asset. Edison International and SCE will adopt this guidance effective January 1, 2018. SCE's nuclear decommissioning trust investments contain equity investments that are classified as available-for-sale. Due to regulatory mechanisms, the change in fair value of these investments has no impact on net income and, therefore, the adoption of this standard is not expected to have a material impact on Edison International's and SCE's consolidated financial statements. In February 2016, the FASB issued an accounting standards update related to lease accounting including enhanced disclosures. 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 adjustment, such as for initial direct costs. 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 have straight-line expense for finance leases, assuming the rate recovery is based upon current payments. Lessees can elect to exclude from the balance sheet short-term contracts one year or less. This guidance is effective January 1, 2019. Early adoption is permitted, but Edison International and SCE do not expect to elect early adoption. 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 evaluating the impact this standard will have on the results of operations and statements of cash flows and lease disclosures. The FASB also 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. The FASB also issued accounting standards updates related to the presentation and classification of certain cash receipts and payments in the statement of cash flows, including a change to the amount of cash, cash equivalents, and restricted cash explained when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. These standards are effective January 1, 2018 and require retrospective application. Restricted cash as of September 30, 2017 was $15 million at Edison International and was less than $1 million at SCE. 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 March 2017, the FASB issued an accounting standards update which amends the current requirements related to the presentation of the components of net periodic benefit cost for an entity's defined benefit pension and other postretirement plans. The adoption of this standard is not expected to have a material impact on Edison International's and SCE's financial position or results of operations, but will result in the separate presentation of service costs as an operating expense and non-service costs within other income and expense and limit the capitalization of benefit costs to the service cost component. During the three and nine months ended September 30, 2017, service costs totaled $45 million and $135 million, respectively, for Edison International and $44 million and $132 million, respectively, for SCE. During the three and nine months ended September 30, 2017, non-service costs were $(14) million and $(32) million, respectively, for Edison International and $(15) million and $(45) million, respectively, for SCE. The new standards update is effective on January 1, 2018. It is required to be applied on a retrospective basis for the presentation of the service cost component and the other components of net benefit cost and on a prospective basis for the capitalization of only the service cost component of net benefit cost.