Oncor Electric Delivery 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 25, 2021	Dec. 31, 2019	Dec. 31, 2018
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	333-100240
Entity Registrant Name	ONCOR ELECTRIC DELIVERY CO LLC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	75-2967830
Entity Address, Address Line One	1616 Woodall Rodgers Fwy.
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75202
City Area Code	214
Local Phone Number	486-2000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	Yes
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float	$ 0
Capital account, interests outstanding	635,000,000	635,000,000	635,000,000	635,000,000
Entity Common Stock, Shares Outstanding		0
Entity Central Index Key	0001193311
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Oncor Electric Delivery Holdings Company LLC [Member]
Entity Outstanding Membership Interests		80.25%
Texas Transmission and Investment LLC [Member]
Entity Outstanding Membership Interests		19.75%

Statements Of Consolidated Inco

Statements Of Consolidated Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statements Of Consolidated Income [Abstract]
Operating revenues (Note 3)	$ 4,511	$ 4,347	$ 4,101
Operating expenses:
Wholesale transmission service	975	1,005	962
Operation and maintenance (Note 11)	925	899	875
Depreciation and amortization	786	723	671
Provision in lieu of income taxes (Notes 1, 4 and 11)	148	138	152
Taxes other than amounts related to income taxes	538	508	496
Total operating expenses	3,372	3,273	3,156
Operating income	1,139	1,074	945
Other deductions and (income) - net (Note 12)	33	63	84
Nonoperating benefit in lieu of income taxes (Note 4)	(12)	(15)	(35)
Interest expense and related charges (Note 12)	405	375	351
Net income	$ 713	$ 651	$ 545

Statements Of Consolidated Comp

Statements Of Consolidated Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statements Of Consolidated Comprehensive Income [Abstract]
Net income	$ 713	$ 651	$ 545
Other comprehensive income (loss):
Cash flow hedges – derivative value net gain (loss) recognized in net income (net of tax expense (benefit) of ($5), $- and $1) (Notes 1 and 8)	(21)	2	2
Defined benefit pension plans (net of tax expense of $-, $- and $45) (Note 9)	9	27	(65)
Total other comprehensive income (loss)	(12)	29	(63)
Comprehensive income	$ 701	$ 680	$ 482

Statements Of Consolidated Co_2

Statements Of Consolidated Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Statements Of Consolidated Comprehensive Income [Abstract]
Cash flow hedges – derivative value net loss recognized in net income (net of tax expense (benefit)	$ (5)	$ 1
Defined benefit pension plans (net of tax expense)		$ 45

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows - operating activities:
Net income	$ 713	$ 651	$ 545
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization, including regulatory amortization	866	806	777
Provision in lieu of deferred income taxes - net	32	55	18
Other - net	(1)	(3)	(3)
Changes in operating assets and liabilities:
Accounts receivable - trade	(78)	(53)	68
Inventories	4	(30)	(25)
Accounts payable - trade	(29)	21	30
Regulatory accounts related to reconcilable tariffs (Note 2)	33	(44)	66
Other - assets	(71)	(204)	33
Other - liabilities	56	76	(27)
Cash provided by operating activities	1,525	1,275	1,482
Cash flows - financing activities:
Issuances of long-term debt (Note 6)	1,810	2,460	1,150
Repayment of long-term debt (Note 6)	(1,164)	(1,094)	(825)
Proceeds of business acquisition bridge loan		600
Repayment of business acquisition bridge loan		(600)
Net increase (decrease) in short-term borrowings (Note 5)	24	(882)	(137)
Capital contributions from members (Note 8)	788	1,978	284
Distributions to members (Note 8)	(356)	(319)	(209)
Debt discount, premium, financing and reacquisition costs – net	(54)	(39)	(14)
Cash provided by financing activities	1,048	2,104	249
Cash flows - investing activities:
Capital expenditures (Note 11)	(2,540)	(2,097)	(1,767)
Business acquisition (Note 13)		(1,324)
Expenditures for third party in joint project	(96)
Reimbursement from third party in joint project	66
Other - net	20	43	18
Cash used in investing activities	(2,550)	(3,378)	(1,749)
Net change in cash and cash equivalents	23	1	(18)
Cash and cash equivalents - beginning balance	4	3	21
Cash and cash equivalents - ending balance	$ 27	$ 4	$ 3

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 27	$ 4
Trade accounts receivable – net (Note 12)	760	661
Amounts receivable from members related to income taxes (Note 11)	7	3
Materials and supplies inventories - at average cost	144	148
Prepayments and other current assets	100	96
Total current assets	1,038	912
Investments and other property (Note 12)	142	133
Property, plant and equipment - net (Note 12)	21,225	19,370
Goodwill (Notes 1 and 12)	4,740	4,740
Regulatory assets (Note 2)	1,779	1,775
Operating lease ROU, third party joint project and other assets (Notes 1 and 7)	248	106
Total assets	29,172	27,036
Current liabilities:
Short-term borrowings (Note 5)	70	46
Long-term debt due currently (Note 5)		608
Trade accounts payable( Note 11)	392	394
Amounts payable to members related to income taxes (Note 11)	23	22
Accrued taxes other than amounts related to income taxes	269	236
Accrued interest	87	83
Operating lease and other current liabilities (Note 7)	279	237
Total current liabilities	1,120	1,626
Long-term debt, less amounts due currently (Note 6)	9,229	8,017
Liability in lieu of deferred income taxes (Notes 1, 4 and 11)	1,923	1,821
Regulatory liabilities (Note 2)	2,855	2,793
Employee benefit obligations (Note 9)	1,808	1,834
Operating lease, third party joint project and other obligations (Note 12)	305	146
Total liabilities	17,240	16,237
Commitments and contingencies (Note 7)
Membership interests (Note 8):
Capital account ― number of interests outstanding 2020 and 2019 – 635,000,000	12,083	10,938
Accumulated other comprehensive loss	(151)	(139)
Total membership interests	11,932	10,799
Total liabilities and membership interests	$ 29,172	$ 27,036

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares	Feb. 25, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets [Abstract]
Capital account, interests outstanding	635,000,000	635,000,000	635,000,000	635,000,000

Statements Of Consolidated Memb

Statements Of Consolidated Membership Interests - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Capital account:
Balance at beginning of period		$ 10,938		$ 8,624	$ 10,938	$ 8,624	$ 8,004
Net income	$ 148	131	$ 133	116	713	651	545
Capital contributions from members (Note 8)					788	1,978	284
Distributions to members (Note 8)					(356)	(319)	(209)
Balance at end of period	12,083		10,938		12,083	10,938	8,624
Total membership interests at end of period	11,932		10,799		11,932	10,799	8,460
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2018-02 [Member]
Capital account:
Balance at beginning of period		4			4
Balance at end of period			4			4
Accumulated Other Comprehensive Income (Loss) [Member]
Capital account:
Balance at beginning of period		(139)		(164)	(139)	(164)	(101)
Net effects of cash flow hedges (net of tax expense (benefit) of ($5), $- and $1)					(21)	2	2
Defined benefit pension plans (net of tax expense of $-, $- and $45) (Note 9)					(9)	(27)	65
Balance at end of period	(151)		(139)		(151)	(139)	(164)
Accumulated Other Comprehensive Income (Loss) [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2018-02 [Member]
Capital account:
Balance at beginning of period		$ 4			4
Balance at end of period			$ 4			$ 4

Statements Of Consolidated Me_2

Statements Of Consolidated Membership Interests (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Statements Of Consolidated Membership Interest [Abstract]
Interests outstanding	635,000,000	635,000,000
Net effects of cash flow hedges, tax expense	$ 5	$ 1
Defined benefit pension plans (net of tax expense)		$ 45

Description Of Business And Sig

Description Of Business And Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Description Of Business And Significant Accounting Policies [Abstract]
Description Of Business And Significant Accounting Policies	1. DESCRIPTION OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES  Description of Business  References in this report to “we,” “our,” “us” and “the company” are to Oncor and/or its subsidiaries as apparent in the context. See “Glossary” for definition of terms and abbreviations.  We are a regulated electricity transmission and distribution company principally engaged in providing delivery services to REPs that sell power in the north-central, eastern, western and panhandle regions of Texas. We are a direct, majority-owned subsidiary of Oncor Holdings, which is indirectly and wholly owned by Sempra. Oncor Holdings owns 80.25% of our membership interests and Texas Transmission owns 19.75% of our membership interests. We are managed as an integrated business; consequently, there are no separate reportable business segments.  Our consolidated financial statements includes the results of our wholly owned indirect subsidiary, NTU, which we acquired as part of the InfraREIT Acquisition that closed on May 16, 2019. NTU is a regulated utility that primarily provides electricity transmission delivery service in the north-central, western and panhandle regions of Texas.  Ring-Fencing Measures  Since 2007, various ring-fencing measures have been taken to enhance our credit quality and the separateness between the Oncor Ring-Fenced Entities and entities with ownership interests in Oncor or Oncor Holdings. These ring-fencing measures serve to mitigate the Oncor Ring-Fenced Entities’ credit exposure to owners of Oncor and Oncor Holdings, and to reduce the risk that the assets and liabilities of Oncor Ring-Fenced Entities would be substantively consolidated with the assets and liabilities of any direct or indirect owners of Oncor and Oncor Holdings in connection with a bankruptcy of any such entities. These measures include the November 200 8 sale of 19.75% of Oncor’s equity interests to Texas Transmission.  In March 201 8, Sempra indirectly acquired Oncor Holdings through the Sempra Acquisition. The Sempra Acquisition was consummated after obtaining the approval of the bankruptcy court in the EFH Bankruptcy Proceedings and the PUCT. The PUCT approval was obtained in Docket No. 47675, and the final order issued in that docket (Sempra Order) outlines certain ring-fencing measures, governance mechanisms and restrictions that apply after the Sempra Acquisition. As a result of these ring-fencing measures, Sempra does not control Oncor, and the ring-fencing measures limit Sempra’s ability to direct the management, policies and operations of Oncor, including the deployment or disposition of Oncor’s assets, declarations of dividends, strategic planning and other important corporate issues and actions.  None of the assets of the Oncor Ring-Fenced Entities are available to satisfy the debt or obligations of any Sempra entity or any other direct or indirect owner of Oncor or Oncor Holdings. The assets and liabilities of the Oncor Ring-Fenced Entities are separate and distinct from those of any Sempra entities and any other direct or indirect owner of Oncor or Oncor Holdings. We do not bear any liability for debt or contractual obligations of Sempra and its affiliates or any other direct or indirect owner of Oncor or Oncor Holdings, and vice versa. Accordingly, our operations are conducted, and our cash flows are managed, independently from Sempra and its affiliates and any other direct or indirect owner of Oncor or Oncor Holdings.  Oncor is a limited liability company governed by a board of directors, not its members. The Sempra Order and our Limited Liability Company Agreement require that the board of directors of Oncor consist of thirteen members, constituted as follows:  · seven Disinterested Directors, who (i) shall be independent directors in all material respects under the rules of the New York Stock Exchange in relation to Sempra or its subsidiaries and affiliated entities and any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, and (ii) shall have no material relationship with Sempra or its subsidiaries or affiliated entities or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, currently or within the previous ten years; · two members designated by Sempra (through Oncor Holdings); · two members designated by Texas Transmission; and · two current or former officers of Oncor (the Oncor Officer Directors), currently Robert S. Shapard and E. Allen Nye, Jr., who are our Chairman of the Board and Chief Executive, respectively.  Until March 9, 2028, in order for a current or former officer of Oncor to be eligible to serve as an Oncor Officer Director, the officer cannot have worked for Sempra or any of its affiliates (excluding Oncor Holdings and Oncor) or any other entity with a direct or indirect ownership interest in Oncor or Oncor Holdings in the ten-year period prior to serving as an Oncor Officer Director. Oncor Holdings, at the direction of STIH, has the right to nominate and/or seek the removal of the Oncor Officer Directors, subject to approval by a majority of the Oncor board of directors. STIH is a wholly owned indirect subsidiary of, and controlled by, Sempra following the Sempra Acquisition.  In addition, the Sempra Order provides that Oncor’s board of directors cannot be overruled by the board of Sempra or any of its subsidiaries on dividend policy, the issuance of dividends or other distributions (except for contractual tax payments), debt issuance, capital expenditures, operation and maintenance expenditures, management and service fees, and appointment or removal of board members, provided that certain actions may also require the additional approval of the Oncor Holdings board of directors. The Sempra Order also provides that any changes to the size, composition, structure or rights of the board must first be approved by the PUCT. In addition, if Sempra acquires Texas Transmission’s interest in Oncor, the two board positions on Oncor’s board of directors that Texas Transmission is entitled to appoint will be eliminated and the size of Oncor’s board of directors will be reduced by two.  Additional regulatory commitments, governance mechanisms and restrictions provided in the Sempra Order and our Limited Liability Company Agreement to ring-fence Oncor from its owners include, among others:  · A majority of the Disinterested Directors of Oncor and the directors designated by Texas Transmission that are present and voting (of which at least one must be present and voting) must approve any annual or multi-year budget if the aggregate amount of capital expenditures or operating and maintenance expenditures in such budget is more than a 10% increase or decrease from the corresponding amounts of such expenditures in the budget for the preceding fiscal year or multi-year period, as applicable; · Oncor may not pay any dividends or make any other distributions (except for contractual tax payments) if a majority of its Disinterested Directors or either of the two directors appointed by Texas Transmission determines that it is in the best interests of Oncor to retain such amounts to meet expected future requirements; · At all times, Oncor will remain in compliance with the debt-to-equity ratio established by the PUCT from time to time for ratemaking purposes, and Oncor will not pay dividends or other distributions (except for contractual tax payments), if that payment would cause its debt-to-equity ratio to exceed the debt-to-equity ratio approved by the PUCT; · If the credit rating on Oncor’s senior secured debt by any of the three major rating agencies falls below BBB (or the equivalent), Oncor will suspend dividends and other distributions (except for contractual tax payments), unless otherwise allowed by the PUCT; · Without the prior approval of the PUCT, neither Sempra nor any of its affiliates (excluding Oncor) will incur, guaranty or pledge assets in respect of any indebtedness that is dependent on the revenues of Oncor in more than a proportionate degree than the other revenues of Sempra or on the membership interests of Oncor, and there will be no debt at STH or STIH at any time following the closing of the Sempra Acquisition; · Neither Oncor nor Oncor Holdings will lend money to or borrow money from Sempra or any of its affiliates (other than Oncor subsidiaries), or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, and neither Oncor nor Oncor Holdings will share credit facilities with Sempra or any of its affiliates (other than Oncor subsidiaries), or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings; · There must be maintained certain “separateness measures” that reinforce the legal and financial separation of Oncor from its owners, including a requirement that dealings between Oncor, Oncor Holdings and their subsidiaries with Sempra, any of Sempra’s other affiliates or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, must be on an arm’s-length basis, limitations on affiliate transactions, separate recordkeeping requirements and a prohibition on Sempra or its affiliates pledging Oncor assets or membership interests for any entity other than Oncor; and · Sempra will continue to hold indirectly at least 51% of the ownership interests in Oncor and Oncor Holdings for at least five years following the closing of the Sempra Acquisition, unless otherwise specifically authorized by the PUCT.  Basis of Presentation  Our consolidated financial statements have been prepared in accordance with GAAP governing rate-regulated operations. All dollar amounts in the financial statements and tables in the notes are stated in millions of U.S. dollars unless otherwise indicated.  Use of Estimates  Preparation of our financial statements requires management to make estimates and assumptions about future events that affect the reporting of assets and liabilities at the balance sheet dates and the reported amounts of revenue and expense, including fair value measurements. In the event estimates and/or assumptions prove to be different from actual amounts, adjustments are made in subsequent periods to reflect more current information. No material adjustments were made to previous estimates or assumptions during the current year.  Revenue Recognition  Oncor’s revenue is billed under tariffs approved by the PUCT and the majority of revenues are related to providing electric delivery service to consumers. Tariff rates are designed to recover the cost of providing electric delivery service including a reasonable rate of return on invested capital. Revenues are generally recognized when the underlying service has been provided in an amount prescribed by the related tariff. See Note 3 for additional information regarding revenues.  Impairment of Long-Lived Assets and Goodwill  We evaluate long-lived assets (including intangible assets with finite lives) for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We also evaluate goodwill for impairment annually on October 1 and whenever events or changes in circumstances indicate that an impairment may exist. The determination of the existence of these and other indications of impairment involves judgments that are subjective in nature and may require the use of estimates in forecasting future results and cash flows.  For our annual goodwill impairment testing, we have the option to first make a qualitative assessment of whether it is more likely than not that our enterprise fair value is less than our enterprise carrying amount before applying the quantitative goodwill impairment test. If we elect to perform the qualitative assessment, we evaluate relevant events and circumstances, including but not limited to, macroeconomic conditions, industry and market considerations, cost factors and the overall financial performance. If, after assessing these qualitative factors, we determine that it is more-likely-than-not that our enterprise fair value is less than our enterprise carrying amount, then we perform a quantitative goodwill impairment test. If, after performing the quantitative goodwill impairment test, we determine that goodwill is impaired, we record the amount of goodwill impairment as the excess of carrying amount over fair value, not to exceed the carrying amount of goodwill.  In each of 2020, 2019 and 2018, we concluded, based on a qualitative assessment, that our estimated enterprise fair value was more likely than not greater than our carrying value. As a result , no quantitative goodwill impairment tests were required and n o impairments were recognized .  Provision in Lieu of Income Taxes  Our tax sharing agreement with Oncor Holdings, Texas Transmission and STH provides for the calculation of amounts related to income taxes for each of Oncor Holdings and Oncor substantially as if these entities were taxed as corporations and requires payments to the members determined on that basis (without duplication for any income taxes paid by a subsidiary of Oncor Holdings).  We are a partnership for U.S. federal income tax purposes. Accordingly, while partnerships are not subject to income taxes, in consideration of the presentation of our financial statements as an entity subject to cost-based regulatory rate-setting processes, with such costs historically including income taxes, the financial statements present amounts determined under the tax sharing agreement as “provision in lieu of income taxes” and “liability in lieu of deferred income taxes”. Such amounts are determined in accordance with the provisions of the accounting guidance for income taxes and accounting standards that provide interpretive guidance for accounting for uncertain tax positions and thus differences between the book and tax bases of assets and liabilities are accounted for as if we were a stand-alone corporation. In the event such amounts are not paid under the tax sharing agreement, it is probable that this regulatory liability will continue to be included in Oncor’s rate setting processes.  We classify any interest and penalties expense related to uncertain tax positions as current provision in lieu of income taxes as discussed in Note 4.  Defined Benefit Pension Plans and Oncor OPEB Plans  We have liabilities under pension plans that offer benefits based on either a traditional defined benefit formula or a cash balance formula and Oncor OPEB plans that offer certain health care and life insurance benefits to eligible employees and their eligible dependents upon the retirement of such employees. Costs of pension and Oncor OPEB plans are dependent upon numerous factors, assumptions and estimates. See Note 9 for additional information regarding pension and OPEB plans.  System of Accounts  Our accounting records have been maintained in accordance with the FERC Uniform System of Accounts as adopted by the PUCT.  Property, Plant and Equipment  Properties are stated at original cost. The cost of self-constructed property additions includes materials and both direct and indirect labor and applicable overhead and an allowance for funds used during construction.  D epreciation of property, plant and equipment is calculated on a straight-line basis over the estimated service lives of the properties based on depreciation rates approved by the PUCT. As is common in the industry, depreciation expense is recorded using composite depreciation rates that reflect blended estimates of the lives of major asset groups as compared to depreciation expense calculated on a component asset-by-asset basis. Depreciation rates include plant removal costs as a component of depreciation expense, consistent with regulatory treatment. Actual removal costs incurred are charged to accumulated depreciation. Accrued removal costs in excess of incurred removal costs are reclassified as a regulatory liability to retire assets in the future.  Regulatory Assets and Liabilities  We are subject to rate regulation and our financial statements reflect regulatory assets and liabilities in accordance with accounting standards related to the effect of certain types of regulation. Regulatory assets and liabilities represent probable future revenues that will be recovered from or refunded to customers through the ratemaking process based on PURA and/or the PUCT’s orders, precedents or substantive rules. Rate regulation is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital subject to PUCT review for reasonableness. Regulatory decisions can have an impact on the recovery of costs, the rate earned on invested capital and the timing and amount of assets to be recovered by rates. See Note 2 for more information regarding regulatory assets and liabilities.  Franchise Taxes  Franchise taxes are assessed to us by local governmental bodies, based on kWh delivered and are a principal component of taxes other than amounts related to income taxes as reported in the income statement. Franchise taxes are not a “pass through” item. The rates we charge customers are intended to recover the franchise taxes, but we are not acting as an agent to collect the taxes from customers.  Allowance for Funds Used During Construction (AFUDC)  AFUDC is a regulatory cost accounting procedure whereby both interest charges on borrowed funds and a return on equity capital used to finance construction are included in the recorded cost of utility plant and equipment being constructed. AFUDC is capitalized on all projects involving construction periods lasting greater than thirty days. The interest portion of capitalized AFUDC is accounted for as a reduction to interest expense and the equity portion of capitalized AFUDC is accounted for as other income. See Note 12 for detail of amounts reducing interest expense and increasing other income.  Cash and Cash Equivalents  For purposes of reporting cash and cash equivalents, highly liquid investments with original maturities of three months or less at the date of purchase are considered to be cash equivalents.  Fair Value of Nonderivative Financial Instruments  The carrying amounts for financial assets classified as current assets and the carrying amounts for financial liabilities classified as current liabilities approximate fair value due to the short maturity of such instruments. The fair values of other financial instruments, for which carrying amounts and fair values have not been presented, are not materially different than their related carrying amounts. The following discussion of fair value accounting standards applies primarily to our determination of the fair value of assets in the pension and Oncor OPEB plans’ trusts (see Note 9) and long-term debt (see Note 6).  Accounting standards related to the determination of fair value define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We use a “mid-market” valuation convention (the mid-point price between bid and ask prices) as a practical expedient to measure fair value for the majority of our assets and liabilities subject to fair value measurement on a recurring basis. We primarily use the market approach for recurring fair value measurements and use valuation techniques to maximize the use of observable inputs and minimize the use of unobservable inputs.  We categorize our assets and liabilities recorded at fair value based upon the following fair value hierarchy:  · Level 1 valuations use quoted prices in active markets for identical assets or liabilities that are accessible at the measurement date. An active market is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. · Level 2 valuations use inputs that, in the absence of actively quoted market prices, are observable for the asset or liability, either directly or indirectly. Level 2 inputs include: (a) quoted prices for similar assets or liabilities in active markets , (b) quoted prices for identical or similar assets or liabilities in markets that are not active, (c) inputs other than quoted prices that are observable for the asset or liability such as interest rates and yield curves observable at commonly quoted intervals and (d) inputs that are derived principally from or corroborated by observable market data by correlation or other means. Our Level 2 valuations utilize over-the-counter broker quotes, quoted prices for similar assets or liabilities that are corroborated by correlations or other mathematical means and other valuation inputs. · Level 3 valuations use unobservable inputs for the asset or liability. Unobservable inputs are used to the extent observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. We use the most meaningful information available from the market combined with internally developed valuation methodologies to develop our best estimate of fair value.  We utilize several different valuation techniques to measure the fair value of assets and liabilities, relying primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities for those items that are measured on a recurring basis.  The fair value of certain investments is measured using the net asset value (NAV) per share as a practical expedient. Such investments measured at NAV are not required to be categorized within the fair value hierarchy.  Derivative Instruments and Mark-to-Market Accounting  From time-to-time we enter into derivative instruments to hedge interest rate risk. If the instrument meets the definition of a derivative under accounting standards related to derivative instruments and hedging activities, the fair value of each derivative is recognized on the balance sheet as a derivative asset or liability and changes in the fair value are recognized in net income, unless criteria for cash flow hedge accounting are met. This recognition is referred to as “mark-to-market” accounting.  Changes in Accounting Standards  Topic 326, “Financial Instruments—Credit Losses” – In June 201 6, the FASB issued ASU No. 2016-13, which changes how entities account for credit losses on receivables and certain other financial assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards. We adopted the new standard effective January 1, 2020. The adoption of the new standard did not have a material impact on our consolidated financial statements.  Topic 848, “Facilitation of the Effects of Reference Rate Reform on Financial Reporting” – In March 202 0, the FASB issued ASU No. 2020-04, which provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. ASU No. 2020-04 is effective for all entities as of March 12, 2020 through December 31, 2022. The standard allows entities to account for contract modifications as an event that does not require reassessment or remeasurement (i.e., as a continuation of the existing contract). Our Credit Facility use s LIBOR as a benchmark for establishing interest rates. Implementation has not had an impact on our consolidated financial statements. In the event we modify our Credit Facility related to the phase-out of LIBOR, we will evaluate the optional expedients and exceptions under the standard. 

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2020
Regulatory Matters [Abstract]
REGULATORY MATTERS	2. REGULATORY MATTERS  Regulatory Assets and Liabilities  Recognition of regulatory assets and liabilities and the periods over which they are to be recovered or refunded through rate regulation reflect the decisions of the PUCT. Components of our regulatory assets and liabilities and their remaining recovery periods as of December 31, 2020 are provided in the table below. Amounts not earning a return through rate regulation are noted.   Remaining Rate Recovery/Amortization Period at At December 31,  December 31, 2020 2020 2019   Regulatory assets:  Employee retirement liability (a)(b)(c) To be determined $ 672 $ 623  Employee retirement costs being amortized 7 years 227 262  Employee retirement costs incurred since the last rate review period (b) To be determined 67 79  Self-insurance reserve (primarily storm recovery costs) being amortized 7 years 266 309  Self-insurance reserve incurred since the last rate review period (primarily storm related) (b) To be determined 256 238  Debt reacquisition costs Lives of related debt 25 29  Under-recovered AMS costs 7 years 149 170  Energy efficiency performance bonus (a) 1 year or less 14 9  Wholesale distribution substation service To be determined 55 34  Unrecovered expenses related to COVID-19 (d) To be determined 27 -  Other regulatory assets Various 21 22  Total regulatory assets 1,779 1,775   Regulatory liabilities:  Estimated net removal costs Lives of related assets 1,262 1,178  Excess deferred taxes Primarily over lives of related assets 1,508 1,574  Over-recovered wholesale transmission service expense (a) 1 year or less 52 30  Unamortized gain on reacquisition of debt Lives of related debt 27 -  Other regulatory liabilities Various 6 11  Total regulatory liabilities 2,855 2,793  Net regulatory assets (liabilities) $ (1,076) $ (1,018) ____________ (a) Not earning a return in the regulatory rate-setting process. (b) Recovery is specifically authorized by statute or by the PUCT, subject to reasonableness review. (c) Represents unfunded liabilities recorded in accordance with pension and OPEB accounting standards. (d) Includes $21 million incremental costs incurred resulting from the effects of the COVID-19 pandemic, including costs related to our pandemic response plan and $6 million related to the COVID-19 Electricity Relief Program.  PUCT Project No. 50664 Issues Related to the State of Disaster for the Coronavirus Disease 2019  In March 202 0, the PUCT issued an order in PUCT Project No. 50664, Issues Related to the State of Disaster for the Coronavirus Disease 2019 , creating the COVID-19 Electricity Relief Program (COVID-19 ERP) to aid certain eligible residential customers unable to pay their electricity bills as a result of the COVID-19 pandemic impacts. Customer enrollment in the COVID-19 ERP closed on August 31, 2020, and financial assistance under the program was available to enrolled residential customers for electricity bills issued on or after March 26, 2020 through September 30, 2020. In connection with the COVID-19 ERP, the PUCT suspended service disconnections due to nonpayment for customers enrolled in the program through September 30, 2020.  To fund the COVID-19 ERP, the PUCT authorized a $0.33 per MWh surcharge to be collected by transmission and distribution utilities through rates and directed ERCOT to provide loans to those transmission and distribution utilities for the initial funding of the COVID-19 ERP. As a result, in April 202 0 we filed a tariff rider implementing the surcharge and received an unsecured loan from ERCOT in the principal amount of $7 million, which was repaid in December 2020 . Surcharge collections we re recorded as a regulatory liability until the funds were used. Surcharge collections could only be used to reimburse transmission and distribution utilities and REPs for eligible unpaid bills from residential customers enrolled in the COVID-19 ERP and to cover costs of a third-party administrator to administer the eligibility process. At December 31, 2020, we had billed $32 million under the rider surcharge. Reimbursements paid by us pursuant to the COVID-19 ERP totaled $38 million through December 31, 2020 (including $18 million of reimbursements to Oncor for electricity delivery charges). As of February 9, 2021, we had billed amounts under the tariff surcharge approximately equal to the reimbursements paid by us pursuant to the COVID- 19 ERP and ceased billing the tariff rider surcharge. The PUCT also authorized the transmission and distribution utilities to use a regulatory asset accounting mechanism and a subsequent process to seek future recovery of expenses resulting from the effects of the COVID-19 pandemic. Therefore, we are recording incremental costs incurred by Oncor resulting from the effects of the COVID-19 pandemic, including costs relating to the implementation of our pandemic response plan, as a regulatory asset. At December 31, 2020, we recorded $21 million with respect to this regulatory asset. For more information on regulatory assets and liabilities , see Note 1 .  InfraREIT Acquisition Approval (PUCT Docket No. 48929)  On May 9, 2019, the PUCT issued a final order in Docket No. 48929 approving the transactions contemplated by the InfraREIT Acquisition, including the SDTS-SU Asset Exchange, and Sempra’s acquisition of an indirect 50% ownership interest in Sharyland Holdings, L.P., the parent of Sharyland. For more information on these transactions, see Note 13.  Regulatory Status of the TCJA  The excess deferred tax related balances above are primarily the result of the TCJA corporate federal income tax rate reduction from 35% to 21%. These regulatory liabilities reflect our obligation, as required by PUCT order in Docket No. 46957, to refund to utility customers any excess deferred tax related balances created by the reduction in the corporate federal income tax rate through reductions in our tariffs.  In 2018, we made filings to incorporate the impacts of the TCJA into our tariffs, including the reduction in the corporate income tax rate from 35% to 21% and amortization of excess deferred federal income taxes. In September 201 8, we reached an unopposed stipulation regarding an overall settlement of the TCJA impacts. The settlement included, on an annual basis, a $144 million decrease in our revenue requirement related to the reduction of income tax expense currently in rates and a $75 million decrease related to amortization of excess deferred federal income taxes. Excess deferred federal income taxes are being refunded as required by the PUCT generally over the lives of the related assets.  The settlement rates were implemented on an interim basis during 2018 and were approved by the PUCT on April 4, 2019. During 2018, interim TCOS rates included refunds of excess deferred federal income taxes that were lower than the amount ultimately approved by the PUCT. Therefore, the PUCT approved in Docket 49160 an additional one-time refund of $9 million , which was made in April and May of 2019.  AMS Final Reconciliation (PUCT Docket No. 49721)  On July 9, 2019, we filed a request with the PUCT for a final reconciliation of our AMS costs. Effective with the implementation of rates pursuant to the Docket No. 46957 rate review, we ceased recovering AMS charges through a surcharge on November 26, 2017, and AMS costs are now being recovered through base rates. We made the following requests in our AMS reconciliation filing:  · a reconciliation of all costs incurred with the $87 million of revenues collected during the final period of the AMS surcharge from January 1, 2017 to November 26, 2017, · a final PUCT determination of the net operating cost savings of $16 million from the final period of our AMS deployment that were used to reduce the amount of costs that were ultimately recovered through our AMS surcharge, · authorization to add the under-recovery of the 2017 AMS costs from this reconciliation proceeding of $6 million to the existing AMS regulatory asset currently being recovered through base rates, and · authorization to establish a regulatory asset to capture the costs associated with this reconciliation proceeding (if approved, Oncor would seek recovery of that regulatory asset in a future Oncor rate case).  On October 8, 2019, Oncor filed a joint motion to admit evidence and for approval of a joint proposed order that implements the requests detailed above, as agreed to by the PUCT staff and the Steering Committee of Cities. On December 16, 2019, the PUCT signed a Final Order approving Oncor’s requests as listed above.  We are involved in various other regulatory proceedings in the normal course of business, the ultimate resolution of which, in the opinion of management, should not have a material effect upon our financial position, results of operations or cash flows.

Revenues

Revenues	12 Months Ended
	Dec. 31, 2020
Revenues [Abstract]
REVENUES	3. REVENUES  General  Our revenue is billed monthly under tariffs approved by the PUCT and the majority of revenues are related to providing electric delivery service to consumers. Tariff rates are designed to recover the cost of providing electric delivery service to customers including a reasonable rate of return on invested capital. As the volumes delivered can be directly measured, our revenues are recognized when the underlying service has been provided in an amount prescribed by the related tariff. We recognize revenue in the amount that we have the right to invoice. Substantially all of our revenues are from contracts with customers except for alternative revenue program revenues discussed below.  Reconcilable Tariffs  The PUCT has designated certain tariffs (primarily TCRF and EECRF) as reconcilable, which means the differences between amounts billed under these tariffs and the related incurred costs are deferred as either regulatory assets or regulatory liabilities. Accordingly, at prescribed intervals, future tariffs are adjusted to either repay regulatory liabilities or collect regulatory assets.  Alternative Revenue Program  The PUCT has implemented an incentive program allowing us to earn performance bonuses by exceeding PURA-mandated energy efficiency program targets. This incentive program and the related performance bonus revenues are considered an “alternative revenue program” under GAAP. Annual performance bonuses are recognized as revenue when approved by the PUCT, typically in the third or fourth quarter each year. In 2020 and 2019, the PUCT approved a $14 million and $9 million bonus that we recognized in revenues in 2020 and 2019, respectively.  Disaggregation of Revenues  The following table reflects electric delivery revenues disaggregated by tariff:   Year Ended December 31,  2020 2019  Operating revenues  Revenues contributing to earnings:  Distribution base revenues $ 2,156 $ 2,143  Transmission base revenues (TCOS revenues)  Billed to third-party wholesale customers 803 681  Billed to REPs serving Oncor distribution customers, through TCRF 446 391  Total transmission base revenues 1,249 1,072  Other miscellaneous revenues 87 77  Total revenues contributing to earnings 3,492 3,292   Revenues collected for pass-through expenses:  TCRF – third-party wholesale transmission service 975 1,005  EECRF 44 50  Revenues collected for pass-through expenses 1,019 1,055   Total operating revenues $ 4,511 $ 4,347  Customers  Our distribution customers consist of approximately 95 REPs and certain electric cooperatives in our certificated service area. The consumers of the electricity we deliver are free to choose their electricity supplier from REPs who compete for their business. Our transmission base revenues are collected from load serving entities benefitting from our transmission system. Our transmission customers consist of municipalities, electric cooperatives and other distribution companies. REP subsidiaries of our two largest customers collectively represented 25% and 18% of our total operating revenues for the year ended 2020, 23% and 18% for the year ended 2019 and 23% and 19% for the year ended 2018. No other customer represented more than 10% of our total operating revenues.  Variability  Our revenues and cash flows are subject to seasonality, timing of customer billings, weather conditions and other electricity usage drivers, with revenues being highest in the summer. Payment is due 35 days after invoicing. Under a PUCT rule relating to the Certification of Retail Electric Providers, write-offs of uncollectible amounts owed by REPs are recoverable as a regulatory asset.  Pass-through Expenses  Revenue equal to expenses that are allowed to be passed-through to customers (primarily third-party wholesale transmission service and energy efficiency program costs) are recognized at the time the expense is recognized. Franchise taxes are assessed by local governmental bodies, based on kWh delivered and are not a “pass-through” item. The rates we charge customers are intended to recover the franchise taxes, but we are not acting as an agent to collect the taxes from customers; therefore, franchise taxes are reported as a principal component of “taxes other than amounts related to income taxes” instead of a reduction to “revenues” in the income statement.  Lubbock Joint Project with LP&L  Oncor is currently involved in an estimated $400 million joint project with LP&L, with costs and resulting assets to ultimately be split by Oncor and LP&L, that involves the build out of transmission lines to join the City of Lubbock to the ERCOT market. Oncor is completing the construction, with LP&L reimbursing Oncor during the project for its portion of the construction costs. The LP&L related assets and a corresponding liability will remain on Oncor’s balance sheet until the end of the project when title to the LP&L portion of the assets transfers to LP&L. As a unique and nonrecurring construction project, the transfer of title will be accounted for as a sale of nonfinancial assets once construction is complete .

Provision In Lieu Of Income Tax

Provision In Lieu Of Income Taxes	12 Months Ended
	Dec. 31, 2020
Provision In Lieu Of Income Taxes [Abstract]
PROVISION IN LIEU OF INCOME TAXES	4. PROVISION IN LIEU OF INCOME TAXES  Components of Liability in Lieu of Deferred Income Taxes  The components of our liability in lieu of deferred income taxes are provided in the table below.     At December 31,  2020 2019   Deferred Tax Related Assets:  Employee benefit liabilities $ 233 $ 224  Regulatory liabilities 48 51  Other 47 28  Total 328 303  Deferred Tax Related Liabilities:  Property, plant and equipment 1,994 1,851  Regulatory assets 255 272  Other 2 1  Total 2,251 2,124  Liability in lieu of deferred income taxes – net $ 1,923 $ 1,821  Provision (Benefit) in Lieu of Income Taxes  The components of our reported provision (benefit) in lieu of income taxes are as follows:    Year Ended December 31,  2020 2019 2018   Reported in operating expenses:  Current:  U.S. federal $ 100 $ 69 $ 112  State 22 22 21  Deferred:  U.S. federal 27 49 21  State - - -  Amortization of investment tax credits (1) (2) (2)  Total reported in operating expenses 148 138 152  Reported in other income and deductions:  Current:  U.S. federal (17) (21) (32)  State - - -  Deferred federal 5 6 (3)  Total reported in other income and deductions (12) (15) (35)  Total provision in lieu of income taxes $ 136 $ 123 $ 117  Reconciliation of provision in lieu of income taxes computed at the U.S. federal statutory rate to provision in lieu of income taxes:    Year Ended December 31,  2020 2019 2018   Income before provision in lieu of income taxes $ 849 $ 774 $ 662  Provision in lieu of income taxes at the U.S. federal statutory rate of 21% $ 178 $ 163 $ 139  Amortization of investment tax credits – net of deferred tax effect (1) (2) (2)  Amortization of excess deferred taxes (52) (52) (18)  Texas margin tax, net of federal tax benefit 18 17 17  Nontaxable gains on benefit plan investments (2) (2) (1)  Other (5) (1) (18)  Reported provision in lieu of income taxes $ 136 $ 123 $ 117  Effective rate 16.0% 15.9% 17.7%  The net amounts of $1.923 billion and $1.821 billion reported in the balance sheets at December 31, 2020 and 2019, respectively, as liability in lieu of deferred income taxes include amounts previously recorded as net deferred tax liabilities. Upon the sale of equity interests to Texas Transmission and Investment LLC in 2008, we became a partnership for U.S. federal income tax purposes, and the temporary differences that gave rise to the deferred taxes will, over time, become taxable to the equity holders. Under a tax sharing agreement among us and our equity holders (see Note 1), we make payments to the equity holders related to income taxes when amounts would have become due to the IRS if Oncor was taxed as a corporation. Accordingly, as the temporary differences become taxable, we will pay the equity holders. In the event such amounts are not paid under the tax sharing agreement, it is probable that this regulatory liability will continue to be included in Oncor’s rate setting processes.  Accounting For Uncertainty in Provision in Lieu of Income Taxes  The statute of limitations is open for our partnership tax returns for the years beginning after December 31, 2016. Texas margin tax returns are under examination or still open for examination for tax years beginning after 2015. We are not a member of any consolidated federal tax group and assess our liability for uncertain tax positions in our partnership returns.  We had no uncertain tax positions in 2020, 2019 and 2018. Noncurrent liabilities included no accrued interest related to uncertain tax positions at December 31, 2020 and 2019. There were no amounts recorded related to interest and penalties in the years ended December 31, 2020, 2019 and 2018. The federal income tax benefit on the interest accrued on uncertain tax positions, if any, is recorded as liability in lieu of deferred income taxes.

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2020
Short-Term Borrowings [Abstract]
SHORT-TERM BORROWINGS	5. SHORT-TERM BORROWINGS  At December 31, 2020 and 2019, outstanding short-term borrowings under our CP Program and Credit Facility consisted of the following:    At December 31,  2020 2019  Total credit facility borrowing capacity $ 2,000 $ 2,000  Commercial paper outstanding (a) (70) (46)  Credit facility outstanding (b) - -  Letters of credit outstanding (c) (9) (10)  Available unused credit $ 1,921 $ 1,944 ____________ (a) The weighted average interest rates for commercial paper were 0.17% and 1.84% at December 31, 2020 and December 31, 2019, respectively. (b) At December 31, 2020, the applicable interest rate for any outstanding borrowings was LIBOR plus 1.25% . (c) Interest rates on outstanding letters of credit at December 31, 2020 and December 31, 2019 were 1.45% and 1.2 0 % , respectively, based on our credit ratings.  CP Program  In March 201 8, we established the CP Program, under which we may issue CP Notes on a private placement basis up to a maximum aggregate face or principal amount outstanding at any time of $2.0 billion . The proceeds of CP Notes issued under the CP Program are used for working capital and general corporate purposes. The CP Program obtains liquidity support from our Credit Facility discussed below. We may utilize either CP Program or the Credit Facility at our option, to meet our funding needs.  Credit Facility  In November 201 7, we entered into a $2.0 billion unsecured Credit Facility to be used for working capital and general corporate purposes, issuances of letters of credit and support for any commercial paper issuances. In November 202 0, we entered into an amendment to the Credit Facility that extended its maturity date for one year to November 202 3. We may request increases in our borrowing capacity in increments of not less than $100 million , not to exceed $400 million in the aggregate, provided certain conditions are met, including lender approvals. The Credit Facility also gives us the option of requesting up to two one-year extensions, with such extensions subject to certain conditions and lender approvals.  The Credit Facility contains terms pursuant to which the interest rates charged under the agreement may be adjusted depending on our credit ratings. Borrowings under the Credit Facility bear interest at per annum rates equal to, at our option, (i) adjusted LIBOR plus a spread ranging from 1.125% to 1.750% depending on credit ratings assigned to our senior secured non-credit enhanced long-term debt or (ii) an alternate base rate (the highest of (1) the prime rate of JPMorgan Chase, (2) the greater of the federal funds effective rate or the overnight banking rate, plus 0.50% , and (3) adjusted LIBOR plus 1.00% ) plus a spread ranging from 0.125% to 0.750% depending on credit ratings assigned to our senior secured non-credit enhanced long-term debt. Amounts borrowed under the Credit Facility, once repaid, can be borrowed again from time to time.  An unused commitment fee is payable quarterly in arrears and upon termination or commitment reduction at a rate equal to 0.075% to 0.225% (such spread depending on certain credit ratings assigned to our senior secured debt) of the daily unused commitments under the Credit Facility. Letter of credit fees on the stated amount of letters of credit issued under the Credit Facility are payable to the lenders quarterly in arrears and upon termination at a rate per annum equal to the spread over adjusted LIBOR. Customary fronting and administrative fees are also payable to letter of credit fronting banks. At December 31, 2020, letters of credit bore interest at 1.45% , and a commitment fee (at a rate of 0.10%) per annum) was payable on the unfunded commitments under the Credit Facility, each based on our current credit ratings.  Under the terms of the Credit Facility, the commitments of the lenders to make loans to us are several and not joint. Accordingly, if any lender fails to make loans to us, our available liquidity could be reduced by an amount up to the aggregate amount of such lender’s commitments under the facility.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2020
Long-Term Debt [Abstract]
LONG-TERM DEBT	6. LONG-TERM DEBT  Our secured debt is secured by a first priority lien on certain transmission and distribution assets equally and ratably with all of Oncor’s other secured indebtedness. See “Deed of Trust” below for additional information. At December 31, 2020 and 2019, our long-term debt consisted of the following:    December 31,  2020 2019   Fixed Rate Secured:  5.75% Senior Notes due September 30, 2020 $ - $ 126  8.50% Senior Notes, Series C, due December 30, 2020 - 14  4.10% Senior Notes, due June 1, 2022 400 400  7.00% Debentures due September 1, 2022 482 482  2.75% Senior Notes due June 1, 2024 500 500  2.95% Senior Notes due April 1, 2025 350 350  0.55% Senior Notes due October 1, 2025 450 -  3.86% Senior Notes, Series A, due December 3, 2025 174 174  3.86% Senior Notes, Series B, due January 14, 2026 38 38  3.70% Senior Notes due November 15, 2028 650 650  5.75% Senior Notes due March 15, 2029 318 318  7.25% Senior Notes, Series B, due December 30, 2029 - 36  2.75% Senior Notes due May 15, 2030 400 -  6.47% Senior Notes, Series A, due September 30, 2030 - 83  7.00% Senior Notes due May 1, 2032 494 500  7.25% Senior Notes due January 15, 2033 323 350  7.50% Senior Notes due September 1, 2038 300 300  5.25% Senior Notes due September 30, 2040 475 475  4.55% Senior Notes due December 1, 2041 400 400  5.30% Senior Notes due June 1, 2042 348 500  3.75% Senior Notes due April 1, 2045 550 550  3.80% Senior Notes due September 30, 2047 325 325  4.10% Senior Notes due November 15, 2048 450 450  3.80% Senior Notes, due June 1, 2049 500 500  3.10% Senior Notes, due September 15, 2049 700 700  3.70% Senior Notes due May 15, 2050 400 -  5.35% Senior Notes due October 1, 2052 300 -  Secured long-term debt 9,327 8,221  Variable Rate Unsecured:  Term loan credit agreement maturing October 6, 2020 - 460  Total long-term debt 9,327 8,681  Unamortized discount and debt issuance costs (98) (56)  Less amount due currently - (608)  Long-term debt, less amounts due currently $ 9,229 $ 8,017  Long-Term Debt-Related Activity in 2020  Senior Secured Notes  2030 Notes and 2050 Notes Issuances  On March 20, 2020, we completed a sale of $400 million aggregate principal amount of 2.75% Senior Secured Notes due May 15, 2030 (2030 Notes) and $400 million aggregate principal amount of 3.70% Senior Secured Notes due May 15, 2050 (2050 Notes). We used the proceeds (net of the initial purchasers’ discount, fees and expenses) of approximately $790 million from the sale of the 2030 Notes and 2050 Notes for general corporate purposes, including the repayment of short-term and long-term debt.  The 2030 and 2050 Notes were issued pursuant to the provisions of an Indenture, dated as of August 1, 2002, between Oncor and The Bank of New York Mellon Trust Company, N.A. (as successor to The Bank of New York Mellon, formerly The Bank of New York) (as amended and supplemented, the Indenture). The 2030 Notes and the 2050 Notes each constitute a separate series of notes under the Indenture, but will be treated together with Oncor’s other outstanding debt securities issued under the Indenture for amendments and waivers and for taking certain other actions.  The 2030 Notes bear interest at a rate of 2.75% per annum and mature on May 15, 2030. The 2050 Notes bear interest at a rate of 3.70% per annum and mature on May 15, 2050. Interest on the 2030 Notes and 2050 Notes is payable in cash semiannually in arrears on May 15 and November 15 of each year, and the first interest payment was due on November 15, 2020. Prior to February 15, 2030, in the case of the 2030 Notes and November 15, 2049, in the case of the 2050 Notes, we may redeem such notes at any time, in whole or in part, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a “make-whole” premium. On and after February 15, 2030, in the case of the 2030 Notes and November 15, 2049, in the case of the 2050 Notes, we may redeem such Notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of such Notes, plus accrued and unpaid interest.  The 2030 Notes and 2050 Notes were issued in a private placement and were not registered under the Securities Act. In August 202 0, we completed an offering with the holders of the 2030 Notes and 2050 Notes to exchange their respective notes for notes that have terms identical in all material respects to the 2030 Notes and 2050 Notes (Exchange Notes), except that the Exchange Notes do not contain terms with respect to transfer restrictions, registration rights and payment of additional interest for failure to observe certain obligations in a certain registration rights agreement. The Exchange Notes were registered on a Form S-4, which was declared effective in July 202 0.  Debt Exchange and 2052 Notes Issuance  On September 23, 2020, we issued $300 million aggregate principal amount of 5.35% Senior Secured Notes due 2052 (the 2052 Notes) in exchange for a like aggregate principal amount of certain of our existing senior secured debt, consisting of (i) $35 million aggregate principal amount of our 7.25% Senior Notes, Series B, due December 30, 2029 (Series B Notes), (ii) $80 million aggregate principal amount of our 6.47% Senior Notes, Series A, due September 30, 2030 (Series A Notes), (iii) $6 million aggregate principal amount of our 7.00% Senior Secured Notes due May 1, 2032, (iv) $27 million aggregate principal amount of our 7.25% Senior Secured Notes due January 15, 2033, and (v) $152 million aggregate principal amount of our 5.30% Senior Secured Notes due June 1, 2042. We received no proceeds from the exchange. The 2052 Notes were issued pursuant to the provisions of the Indenture. The 2052 Notes constitute a separate series of notes under the Indenture, but will be treated together with our other outstanding debt securities issued under the Indenture for amendments and waivers and for taking certain other actions.  The 2052 Notes bear interest at a rate of 5.35% per annum and mature on October 1, 2052. Interest on the 2052 Notes is payable in cash semi-annually in arrears on April 1 and October 1 of each year, and the first interest payment is due on April 1, 2021. Prior to April 1, 2052, we may redeem the 2052 Notes at any time, in whole or in part, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a “make-whole” premium. On and after April 1, 2052, we may redeem the 2052 Notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of such 2052 Notes, plus accrued and unpaid interest.  The 2052 Notes were issued in a private placement and were not registered under the Securities Act. We have agreed, subject to certain exceptions, to register with the SEC notes having substantially identical terms as the 2052 Notes (except for provisions relating to the transfer restriction and payment of additional interest) as part of our offer to exchange freely tradable exchange notes for the 2052 Notes. We have agreed to use commercially reasonable efforts to cause the exchange offer to be completed within 315 days after the issue date of the 2052 Notes. If a registration statement for the exchange offer is not declared effective by the SEC within 270 days after the issue date of the 2052 Notes or the exchange offer is not completed within 315 days after the issue date of the 2052 Notes (an exchange default), then the annual interest rate of the 2052 Notes will increase 50 basis points per annum until the earlier of the expiration of the exchange default or the second anniversary of the issue date of the 2052 Notes.  2025 Notes Issuance  On September 28, 2020, we issued $450 million aggregate principal amount of 0.55% Senior Secured Notes due 2025 (the 2025 Notes). We intend to use the proceeds (net of the initial purchasers’ discount, fees and expenses) of approximately $443 million from the sale of the 2025 Notes to finance or refinance, in whole or in part, eligible projects consisting of investments in or expenditures with minority- and women-owned business suppliers pursuant to our sustainable bond framework. The net proceeds may be temporarily invested in cash, cash equivalents and/or U.S. government securities in accordance with our cash management policies or used to repay certain other indebtedness, or both.  The 2025 Notes were issued pursuant to the provisions of the Indenture. The 2025 Notes constitute a separate series of notes under the Indenture, but will be treated together with our other outstanding debt securities issued under the Indenture for amendments and waivers and for taking certain other actions. The 2025 Notes bear interest at a rate of 0.55% per annum and mature on October 1, 2025. Interest on the 2025 Notes is payable in cash semi-annually in arrears on April 1 and October 1 of each year, and the first interest payment is due on April 1, 2021. Prior to September 1, 2025, we may redeem the 2025 Notes at any time, in whole or in part, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a “make-whole” premium. On and after September 1, 2025, we may redeem the 2025 Notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of the 2025 Notes, plus accrued and unpaid interest.  The 2025 Notes were issued in a private placement and were not registered under the Securities Act. We have agreed, subject to certain exceptions, to register with the SEC notes having substantially identical terms as the 2025 Notes (except for provisions relating to the transfer restriction and payment of additional interest) as part of our offer to exchange freely tradable exchange notes for the 2025 Notes. We have agreed to use commercially reasonable efforts to cause the exchange offer to be completed within 315 days after the issue date of the 2025 Notes. If a registration statement for the exchange offer is not declared effective by the SEC within 270 days after the issue date of the 2025 Notes or the exchange offer is not completed within 315 days after the issue date of the 2025 Notes (an exchange default), then the annual interest rate of the 2025 Notes will increase 50 basis points per annum until the earlier of the expiration of the exchange default or the second anniversary of the issue date of the 2025 Notes.  January 202 0 Term Loan Credit Agreement  On January 28, 2020, we entered into a $450 million unsecured term loan credit agreement that had a maturity date of June 1, 2021 ( January 202 0 Term Loan Credit Agreement). We borrowed an aggregate of $450 million under the January 202 0 Term Loan Credit Agreement, consisting of $163 million on January 29, 2020, $55 million on February 28, 2020 and $232 million on March 17, 2020. The proceeds from each borrowing were used for general corporate purposes, including the repayment of notes outstanding under our CP Program. Loans under the January 202 0 Term Loan Credit Agreement bore interest at per annum rates equal to LIBOR plus 0.50% . On December 23, 2020, we repaid all outstanding borrowings under the January 202 0 Term Loan Credit Agreement, and as a result it is no longer in effect.  March 202 0 Term Loan Credit Agreement  On March 23, 2020, we entered into an unsecured term loan credit agreement ( March 202 0 Term Loan Credit Agreement) with a commitment equal to an aggregate principal amount of $350 million . We entered into an amendment to the March 202 0 Term Loan Credit Agreement in June 202 0. As amended, the March 202 0 Term Loan Credit Agreement had a maturity date of June 30, 2021 and provided for loans to bear interest at per annum rates equal to LIBOR plus 0.95% . We borrowed an aggregate of $110 million under the March 202 0 Term Loan Credit Agreement, consisting of $15 million and $95 million on June 30, 2020 and July 31, 2020, respectively. The proceeds from each borrowing were used for general corporate purposes, including the repayment of notes outstanding under our CP Program. On September 28, 2020, we repaid all outstanding borrowings under the March 202 0 Term Loan Credit Agreement, and as a result it is no longer in effect.  Interest Rate Hedge Transactions  In February and March of 2020, we entered into interest rate hedge transactions hedging the variability of benchmark bond rates used to determine interest rates on anticipated issuances of ten-year and thirty-year senior secured notes. The hedges were terminated in March 202 0 upon our issuance of the 2030 Notes and 2050 Notes. We recognized a $29 million ($23 million after-tax) loss related to the fair value of the hedge transactions in accumulated other comprehensive loss. We expect approximately $4 million of the amount reported in accumulated other comprehensive loss at December 31, 2020 related to interest rate hedges to be reclassified into net income as an increase to interest expense within the next 12 months, including $2 million from the current year transactions.  Debt Repayments  Repayments of long-term debt during the year ended December 31, 2020 included $14 million principal amount of our 8.50% Senior Secured Notes, Series C, due December 30, 2020 (Series C Notes), $126 million aggregate principal amount of our 5.75% Senior Secured Notes due September 30, 2020, $110 million principal amount borrowed under the March 202 0 Term Loan Credit Agreement, $450 million principal amount borrowed under the January 202 0 Term Loan Credit Agreement, $460 million principal amount borrowed under a term loan c redit agreement entered into in September 2019 (2019 Term Loan Credit Agreement) and $5 million principal amount of the quarterly amortizing debt for our Series A Notes, Series B Notes, and Series C Notes . The Series A Notes, Series B Notes, and Series C Notes were issued pursuant to a note purchase agreement, dated as of May 3, 2019. As a result of the September 202 0 senior secured notes exchange, in which all of the outstanding Series A Notes and Series B Notes were exchanged for a like principal amount of 2052 Notes, and the December 30, 2020 repayment of the Series C Notes upon maturity, no notes remain outstanding under that note purchase agreement. The $460 million principal amount repaid under the 2019 Term Loan Credit Agreement, the $450 million principal amount repaid under the January 202 0 Term Loan Credit Agreement and the $110 million principal amount repaid under the March 202 0 Term Loan Credit Agreement constituted all amounts outstanding under those respective agreements, and as a result of those repayments, the 2019 Term Loan Credit Agreement, January 202 0 Term Loan Credit Agreement and March 202 0 Term Loan Credit Agreement are no longer in effect.  Deed of Trust  Our secured debt is secured equally and ratably by a first priority lien on certain Oncor transmission and distribution assets. The property is mortgaged under the Deed of Trust. The Deed of Trust permits us to secure indebtedness with the lien of the Deed of Trust up to the aggregate of (i) the amount of available bond credits, and (ii) 85% of the lower of the fair value or cost of certain property additions that could be certified to the Deed of Trust collateral agent. At December 31, 2020, the amount of available bond credits was $2.115 billion and the amount of future debt we could secure with property additions, subject to those property additions being certified to the Deed of Trust collateral agent, was $3.328 billion .  Borrowings under the CP Program, the Credit Facility and our term loan credit agreements are not secured.  Maturities  Long-term debt maturities at December 31, 2020, are as follows:    Year Amount  2021 $ -  2022 882  2023 -  2024 500  2025 974  Thereafter 6,971  Unamortized discount and debt issuance costs (98)  Total $ 9,229  Fair Value of Long-Term Debt  At December 31, 2020 and 2019, the estimated fair value of our long-term debt (including current maturities) totaled $11.638 billion and $10.003 billion , respectively, and the carrying amount totaled $9.229 billion and $8.625 billion , respectively. The fair value is estimated using observable market data, representing Level 2 valuations under accounting standards related to the determination of fair value.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies [Abstract]
COMMITMENTS AND CONTINGENCIES	7. COMMITMENTS AND CONTINGENCIES  Leases  General  A lease exists when a contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. As lessee, our leased assets primarily consist of our vehicle fleet and real estate leased for company offices and service centers. Our leases are accounted for as operating leases for both GAAP and rate-making purposes. We generally recognize operating lease costs on a straight-line basis over the lease term in operating expenses. We are not a lessor to any material lease contracts.  As of the lease commencement date, we recognize a lease liability for our obligation to make lease payments, which we initially measure at present value using our incremental borrowing rate at the date of lease commencement, unless the rate implicit in the lease is readily determinable. We determine our incremental borrowing rate based on the rate of interest that we would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term in a similar economic environment. We also record a ROU asset for our right to use the underlying asset, which is initially equal to the lease liability and adjusted for any lease payments made at or before lease commencement, lease incentives and any initial direct costs.  Some of our lease agreements contain nonlease components, which represent items or activities that transfer a good or service. We separate lease components from nonlease components, if any, for our fleet vehicle and real estate leases for purposes of calculating the related lease liability and ROU asset.  Certain of our leases include options to extend the lease terms for up to 20 years, while others include options to terminate early. Our lease liabilities and ROU assets are based on lease terms that may include such options to extend or terminate the lease when it is reasonably certain that we will exercise that option.  Short-term Leases  Some of our contracts are short-term leases, which have a lease term of 12 months or less at lease commencement. As allowed by GAAP, we do not recognize a lease liability or ROU asset arising from short-term leases for all existing classes of underlying assets. We recognize short-term lease costs on a straight-line basis over the lease term.  Lease Obligations, Lease Costs and Other Supplemental Data  The following tables summarize lease information on the consolidated balance sheet at December 31, 2020 and 2019 .     At December 31,  2020 2019  Operating Leases:  ROU assets:  Operating lease ROU, third-party joint project and other assets $ 132 $ 92   Lease liabilities:  Operating lease and other current liabilities $ 29 $ 26  Operating lease, third-party joint project and other obligations 124 66  Total operating lease liabilities $ 153 $ 92   Weighted-average remaining lease term (in years) 7 4  Weighted-average discount rate 2.8% 3.3%  The components of lease costs and cash paid for amounts included in the measurement of lease liabilities in 2020 and 2019 were as follows:    Year Ended December 31,  2020 2019  Operating lease cost:  Operating lease costs (including amounts allocated to property, plant and equipment) $ 42 $ 40  Short-term lease costs 10 34  Total operating lease costs $ 52 $ 74   Operating lease payments:  Cash paid for amounts included in the measurement of lease liabilities $ 35 $ 32   The table below presents the maturity analysis of our lease liabilities and reconciliation to the present value of lease liabilities:      Year Amount  2021 $ 33  2022 30  2023 23  2024 17  2025 9  Thereafter 58  Total undiscounted lease payments 170  Less imputed interest (17)  Total operating lease obligations $ 153   Capital Expenditures  As part of the Sempra Acquisition, Oncor has committed to make minimum aggregate capital expenditures equal to at least $7.5 billion over the five year period ending December 31, 2022. Our capital expenditures from January 1, 2018 to December 31, 2020 totaled $6.4 billion .  Energy Efficiency Spending  We are required to annually invest in programs designed to improve customer electricity demand efficiencies to satisfy ongoing regulatory requirements. The requirement for the year 2021 is $52 million , which is recoverable in rates.  Legal/Regulatory Proceedings  We are involved in various legal and administrative proceedings in the normal course of business, the ultimate resolution of which, in the opinion of management, should not have a material effect upon our financial position, results of operations or cash flows.  Labor Contracts  At December 31, 2020, approximately 17% of our full time employees were represented by a labor union and covered by a collective bargaining agreement that expires in October 202 2 .  Environmental Contingencies  We must comply with environmental laws and regulations applicable to the handling and disposal of hazardous waste. We are in compliance with all current laws and regulations; however, the impact, if any, of changes to existing regulations or the implementation of new regulations is not determinable. The costs to comply with environmental regulations can be significantly affected by the following external events or conditions:  · changes to existing state or federal regulation by governmental authorities having jurisdiction over control of toxic substances and hazardous and solid wastes, and other environmental matters, and · the identification of additional sites requiring clean-up or the filing of other complaints in which we may be asserted to be a potential responsible party.  We have not identified any significant potential environmental liabilities at this time.

Membership Interests

Membership Interests	12 Months Ended
	Dec. 31, 2020
Membership Interests [Abstract]
MEMBERSHIP INTERESTS	8. MEMBERSHIP INTERESTS  Cash Contributions   On February 16, 2021, we received cash capital contributions from our members totaling $63 million . During 2020, we received the following capital cash contributions from our members.     Received Amount  December 23, 2020 $ 361  December 22, 2020 89  October 27, 2020 77  July 28, 2020 87  April 27, 2020 87  February 18, 2020 87  $ 788  Cash Distributions  Distributions are limited by the requirement to maintain our regulatory capital structure at or below the debt-to-equity ratio established periodically by the PUCT for ratemaking purposes. The PUCT has the authority to determine what types of debt and equity are included in a utility’s debt-to-equity ratio. For purposes of this ratio, debt is calculated as long-term debt including any finance leases plus unamortized gains on reacquired debt less unamortized issuance expenses, premiums and losses on reacquired debt. Equity is calculated as membership interests determined in accordance with GAAP, excluding accumulated other comprehensive loss and the effects of acquisition acc ounting from a 2007 transaction.  The PUCT order issued in the Sempra Acquisition and our l imited l iability c ompany a greement set forth various restrictions on distributions to our members. Among those restrictions is the commitment that we will make no distributions that would cause us to exceed the PUCT’s authorized debt-to-equity ratio. Our current authorized regulatory capital structure is 57.5% debt to 42.5% equity. The distribution restrictions also include the ability of our board, a majority of the Disinterested Directors, or either of the two member directors designated by Texas Transmission to limit distributions to the extent each determines it is necessary to meet expected future requirements of Oncor (including continuing compliance with the PUCT debt-to-equity ratio commitment). At December 31, 2020, our regulatory capitalization was 52.8% debt to 47.2% equity, and as a result we had $1.426 billion available to distribute to our members.  On February 17, 2021, our board of directors declared a cash distribution of $96 million , which was paid to our members on February 18, 2021. During 2020, our board of directors declared, and we paid, the following cash distributions to our members:   Declaration Date Payment Date Amount  October 28, 2020 October 29, 2020 $ 82  July 29, 2020 July 30, 2020 92  April 29, 2020 April 30, 2020 91  February 19, 2020 February 20, 2020 91  $ 356  During 2019, our board of directors declared, and we paid, the following cash distributions to our members:     Declaration Date Payment Date Amount  October 29, 2019 October 31, 2019 $ 106  July 30, 2019 July 31, 2019 71  May 1, 2019 May 2, 2019 71  February 20, 2019 February 22, 2019 71  $ 319  Accumulated Other Comprehensive Income (Loss) (AOCI)  The following table presents the changes to AOCI for the years ended December 31, 2020, 2019 and 2018 net of tax.     Cash Flow Hedges – Interest Rate Swap Defined Benefit Pension and OPEB Plans Accumulated Other Comprehensive Income (Loss)   Balance at December 31, 2017 $ (18) $ (83) $ (101)  Defined benefit pension plans - (65) (65)  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $-) 2 - 2  Balance at December 31, 2018 $ (16) $ (148) $ (164)  Defined benefit pension plans - 27 27  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $-) 2 - 2  Amounts reclassified from accumulated other comprehensive income (loss) to capital account (4) - (4)  Balance at December 31, 2019 $ (18) $ (121) $ (139)  Defined benefit pension plans - 9 9  Cash flow hedges — net decrease in fair value of derivatives (net of tax benefit of $6) (24) - (24)  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $1) 3 - 3  Balance at December 31, 2020 $ (39) $ (112) $ (151) 

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2020
Employee Benefit Plans [Abstract]
EMPLOYEE BENEFIT PLANS	9. EMPLOYEE BENEFIT PLANS  Regulatory Recovery of Pension and OPEB Costs  PURA provides for our recovery of pension and OPEB costs applicable to services of our active and retired employees, as well as services of certain EFH Corp./Vistra active and retired employees for periods prior to the deregulation and disaggregation of EFH Corp.’s electric utility businesses effective January 1, 2002 (recoverable service). Accordingly, in 2005, we entered into an agreement with a predecessor of EFH Corp. whereby we assumed responsibility for applicable pension and OPEB costs related to those personnel’s recoverable service. We subsequently entered into agreements with EFH Corp. and a Vistra affiliate regarding provision of these benefits. Pursuant to our agreement with the Vistra affiliate, we now sponsor an OPEB plan that provides certain retirement healthcare and life insurance benefits to eligible former Oncor, EFH Corp. and Vistra employees for whom both Oncor and Vistra bear a portion of the benefit responsibility. See “OPEB Plans” below for more information.  We are authorized to establish a regulatory asset or liability for the difference between the amounts of pension and OPEB costs approved in current billing rates and the actual amounts that would otherwise have been recorded as charges or credits to earnings related to recoverable service. Amounts deferred are ultimately subject to regulatory approval. At December 31, 2020 and 2019, we had recorded regulatory assets totaling $966 million and $ 964 million , respectively, related to pension and OPEB costs, including amounts related to deferred expenses as well as amounts related to unfunded liabilities that otherwise would be recorded as other comprehensive income.  We have also assumed primary responsibility for pension benefits of a closed group of retired and terminated vested plan participants not related to our regulated utility business (non-recoverable service) in a 2012 transaction. Any retirement costs associated with non-recoverable service are not recoverable through rates.  Pension Plans  We sponsor the Oncor Retirement Plan and also have liabilities related to the Vistra Retirement Plan, both of which are qualified pension plans under Section 401(a) of the Code, and are subject to the provisions of ERISA. Employees do not contribute to either plan. These pension plans provide benefits to participants under one of two formulas: (i) a Cash Balance Formula under which participants earn monthly contribution credits based on their compensation and a combination of their age and years of service, plus monthly interest credits or (ii) a Traditional Retirement Plan Formula based on years of service and the average earnings of the three years of highest earnings. The interest component of the Cash Balance Formula is variable and is determined using the yield on 30-year Treasury bonds. The weighted-average interest crediting rate assumption for the Cash Balance Formula was 3.0% for 2020. Under the Cash Balance Formula, future increases in earnings will not apply to prior service costs.  All eligible employees hired after January 1, 2001 participate under the Cash Balance Formula. Certain employees, who, prior to January 1, 2002, participated under the Traditional Retirement Plan Formula, continue their participation under that formula. It is Oncor’s policy to fund its plans on a current basis to the extent required under existing federal tax and ERISA regulations.  We also have the Supplemental Retirement Plan for certain employees whose retirement benefits cannot be fully earned under the qualified retirement plan. Supplemental Retirement Plan amounts are included in the reported pension amounts below.  At December 31, 2020, the pension plans’ projected benefit obligation included a net actuarial loss of $302 million for 2020 due primarily to a decrease in the discount rate. Actual returns on the plans’ assets in 2020 were more than the expected return on assets by $241 million . We expect the pension plans’ amortizations of net actuarial losses to be $52 million in 2021.  OPEB Plans  We currently sponsor two OPEB Plans. One plan covers our eligible current and future retirees whose services are 100% attributed to the regulated business. Effective January 1, 2018, we established a second plan to cover eligible retirees of Oncor and EFH Corp./Vistra whose employment services were assigned to both Oncor (or a predecessor regulated utility business) and the non-regulated business of EFH Corp./Vistra. Vistra is solely responsible for its portion of the liability for retiree benefits related to those retirees.  Oncor’s contribution policy for the OPEB Plans is to place in irrevocable external trusts dedicated to the payment of OPEB expenses an amount at least equal to the OPEB expense recovered in rates.  At December 31, 2020, the Oncor OPEB Plans’ projected benefit obligation included a net actuarial loss of $20 million for 2020, including $65 million gain associated with mortality assumption changes, and updates to health care claims and trend assumptions, offset by a loss of $85 million due to a decrease in the discount rate. Actual returns on Oncor OPEB Plans’ assets in 2020 were more than the expected return on assets by $7 million . We expect the Oncor OPEB Plans’ amortizations of net actuarial losses to increase by $8 million in 2021 reflecting these changes.  Pension and OPEB Costs Recognized as Expense  Pension and OPEB amounts provided herein include amounts related only to our obligations with respect to the various plans based on actuarial computations and reflect our employee and retiree demographics as described above. Our net costs related to pension and the Oncor OPEB Plans were comprised of the following:      Year Ended December 31,  2020 2019 2018   Pension costs $ 71 $ 63 $ 77  OPEB costs 19 41 70  Total benefit costs 90 104 147  Less amounts recognized principally as property or a regulatory asset (13) (27) (69)  Net amounts recognized as operation and maintenance expense or other deductions $ 77 $ 77 $ 78  The calculated value method is used to determine the market-related value of the assets held in the trust for purposes of calculating our pension costs. Realized and unrealized gains or losses in the market-related value of assets are included over a rolling four -year period. Each year, 25% of such gains and losses for the current year and for each of the preceding three years is included in the market-related value. Each year, the market-related value of assets is increased for contributions to the plan and investment income and is decreased for benefit payments and expenses for that year.  The fair value method is used to determine the market-related value of the assets held in the trust for purposes of calculating OPEB cost. Detailed Information Regarding Pension and OPEB Benefits  The following pension and OPEB information is based on December 31, 2020, 2019 and 2018 measurement dates:     Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2018 2020 2019 2018   Assumptions Used to Determine Net Periodic Pension and OPEB Costs:  Discount rate 3.13% 4.18% 3.54% 3.29% 4.41% 3.73%  Expected return on plan assets 4.94% 5.42% 5.11% 5.90% 6.19% 6.20%  Rate of compensation increase 4.64% 4.53% 4.46% - - -   Components of Net Pension and OPEB Costs:  Service cost $ 29 $ 25 $ 27 $ 6 $ 6 $ 8  Interest cost 103 128 121 32 43 44  Expected return on assets (109) (119) (120) (8) (7) (9)  Amortization of prior service cost (credit) - - - (20) (20) (30)  Amortization of net loss 48 29 49 10 19 57  Curtailment cost (credit) - - - (1) - -  Net periodic pension and OPEB costs $ 71 $ 63 $ 77 $ 19 $ 41 $ 70   Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:  Curtailment $ - $ - $ - $ 2 $ - $ -  Net loss (gain) 61 - 67 14 (22) (177)  Amortization of net loss (48) (29) (49) (10) (19) (57)  Amortization of prior service (cost) credit - - - 20 20 30  Total recognized as regulatory assets or other comprehensive income 13 (29) 18 26 (21) (204)  Total recognized in net periodic pension and OPEB costs and as regulatory assets or other comprehensive income $ 84 $ 34 $ 95 $ 45 $ 20 $ (134)    Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2018 2020 2019 2018   Assumptions Used to Determine Benefit Obligations at Period End:  Discount rate 2.40% 3.13% 4.18% 2.58% 3.29% 4.41%  Rate of compensation increase 4.80% 4.64% 4.53% - - -    Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2020 2019   Change in Projected Benefit Obligation:  Projected benefit obligation at beginning of year $ 3,400 $ 3,162 $ 999 $ 1,006  Service cost 29 25 6 6  Interest cost 103 128 32 43  Participant contributions - - 18 19  Actuarial loss (gain) 302 367 20 (5)  Benefits paid (165) (164) (63) (70)  Curtailment - - 1 -  Settlements (73) (118) - -  Projected benefit obligation at end of year $ 3,596 $ 3,400 $ 1,013 $ 999  Accumulated benefit obligation at end of year $ 3,433 $ 3,283 $ - $ -   Change in Plan Assets:  Fair value of assets at beginning of year $ 2,494 $ 2,249 $ 141 $ 132  Actual return on assets 350 486 14 25  Employer contributions 134 41 35 35  Participant contributions - - 18 19  Benefits paid (165) (164) (63) (70)  Settlements (73) (118) - -  Fair value of assets at end of year $ 2,740 $ 2,494 $ 145 $ 141   Funded Status:  Projected benefit obligation at end of year $ (3,596) $ (3,400) $ (1,013) $ (999)  Fair value of assets at end of year 2,740 2,494 145 141  Funded status at end of year $ (856) $ (906) $ (868) $ (858)    Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2020 2019   Amounts Recognized in the Balance Sheet Consist of:  Liabilities:  Other current liabilities $ (5) $ (5) $ (14) $ (15)  Other noncurrent liabilities (863) (901) (854) (843)  Net liability recognized $ (868) $ (906) $ (868) $ (858)  Assets:  Other noncurrent assets $ 12 $ - $ - $ -  Regulatory assets:  Net loss 556 531 132 129  Prior service credit - - (16) (37)  Net regulatory assets recognized 556 531 116 92  Net assets recognized $ 568 $ 531 $ 116 $ 92  Accumulated other comprehensive net loss $ 108 $ 120 $ 3 $ 1  The following tables provide information regarding the assumed health care cost trend rates.    Year Ended December 31,  2020 2019   Assumed Health Care Cost Trend Rates – Not Medicare Eligible:  Health care cost trend rate assumed for next year 6.90% 7.20%  Rate to which the cost trend is expected to decline (the ultimate trend rate) 4.50% 4.50%  Year that the rate reaches the ultimate trend rate 2029 2029   Assumed Health Care Cost Trend Rates – Medicare Eligible:  Health care cost trend rate assumed for next year 7.80% 8.00%  Rate to which the cost trend is expected to decline (the ultimate trend rate) 4.50% 4.50%  Year that the rate reaches the ultimate trend rate 2030 2029  The following table provides information regarding pension plans with projected benefit obligations (PBO) and accumulated benefit obligations (ABO) in excess of the fair value of plan assets.     At December 31,  2020 2019  Pension Plans with PBO and ABO in Excess of Plan Assets (a):  Projected benefit obligations $ 3,596 $ 3,400  Accumulated benefit obligations 3,433 3,283  Plan assets 2,740 2,494 _________ (a) PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan are included . Oncor ’s obligations with respect to the Vistra Retirement Plan are overfunded. As of December 31, 2020, PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan were $196 million , $194 million and $208 million , respectively. As of December 31, 2019, PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan were $187 million , $184 million and $197 million , respectively.  The following table provides information regarding OPEB plans with accumulated projected benefit obligations (APBO) in excess of the fair value of plan assets.    At December 31,  2020 2019  OPEB Plans with APBO in Excess of Plan Assets  Accumulated postretirement benefit obligations $ 1,013 $ 999  Plan assets 145 141  Pension and OPEB Plans Investment Strategy and Asset Allocations  Our investment objective for the retirement plans is to invest in a suitable mix of assets to meet the future benefit obligations at an acceptable level of risk, while minimizing the volatility of contributions. Equity securities are held to achieve returns in excess of passive indexes by participating in a wide range of investment opportunities. International equity, real estate securities and credit strategies (high yield bonds, emerging market debt and bank loans) are used to further diversify the equity portfolio. International equity securities may include investments in both developed and emerging international markets. Fixed income securities include primarily corporate bonds from a diversified range of companies, U.S. Treasuries and agency securities and money market instruments. Our investment strategy for fixed income investments is to maintain a high grade portfolio of securities, which assists us in managing the volatility and magnitude of plan contributions and expense while maintaining sufficient cash and short-term investments to pay near-term benefits and expenses.  The Oncor Retirement Plan’s investments are managed in two pools: one pool associated with the recoverable service portion of plan obligations related to Oncor’s regulated utility business, and a second pool associated with the non-recoverable service portion of plan obligations not related to Oncor’s regulated utility business. Each pool is invested in a broadly diversified portfolio as shown below. The second pool represents 25% of total investments at December 31, 2020.  The target asset allocation ranges of the pension plan’s investments by asset category are as follows:    Target Allocation Ranges  Asset Category Recoverable Non-recoverable   International equities 13% - 21% 6% - 12%  U.S. equities 16% - 24% 8% - 14%  Real estate 3% - 7% -  Credit strategies 5% - 10% 5% - 9%  Fixed income 45% - 55% 68% - 78%  Our investment objective for the Oncor OPEB Plans primarily follows the objectives of the pension plans discussed above, while maintaining sufficient cash and short-term investments to pay near-term benefits and expenses. The actual amounts at December 31, 2020 provided below are consistent with the asset allocation targets.  Fair Value Measurement of Pension Plans’ Assets  At December 31, 2020 and 2019, pension plans’ assets measured at fair value on a recurring basis consisted of the following:    At December 31, 2020  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 220 $ 1 $ - $ 221  International 330 1 - 331  Fixed income securities:  Corporate bonds (a) - 910 - 910  U.S. Treasuries - 46 - 46  Other (b) - 57 - 57  Total assets in the fair value hierarchy $ 550 $ 1,015 $ - 1,565  Total assets measured at net asset value (c) 1,175  Total fair value of plan assets $ 2,740   At December 31, 2019  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 194 $ 2 $ - $ 196  International 290 1 - 291  Fixed income securities:  Corporate bonds (a) - 908 - 908  U.S. Treasuries - 147 - 147  Other (b) - 63 - 63  Real estate - - 3 3  Total assets in the fair value hierarchy $ 484 $ 1,121 $ 3 1,608  Total assets measured at net asset value (c) 886  Total fair value of plan assets $ 2,494 _____________ (a) Substantially all corporate bonds are rated investment grade by Fitch, Moody’s or S&P. (b) Other consists primarily of municipal bonds, emerging market debt, bank loans and fixed income derivative instruments. (c) Fair value was measured using the net asset value (NAV) per share as a practical expedient as the investments did not have a readily determinable fair value and are not required to be classified in the fair value hierarchy. The NAV fair value amounts presented here are intended to permit a reconciliation to the total fair value of plan assets.  Fair Value Measurement of Oncor OPEB Plans’ Assets  At December 31, 2020 and 2019, the Oncor OPEB Plans’ assets measured at fair value on a recurring basis consisted of the following:    At December 31, 2020  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 9 $ - $ - $ 9  Equity securities:  U.S. 24 - - 24  International 25 - - 25  Fixed income securities:  Corporate bonds (a) - 34 - 34  U.S. Treasuries - 1 - 1  Other (b) 19 3 - 22  Total assets in the fair value hierarchy $ 77 $ 38 $ - 115  Total assets measured at net asset value (c) 30  Total fair value of plan assets $ 145   At December 31, 2019  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 6 $ - $ - $ 6  Equity securities:  U.S. 24 - - 24  International 28 - - 28  Fixed income securities:  Corporate bonds (a) - 31 - 31  U.S. Treasuries - 3 - 3  Other (b) 22 2 - 24  Total assets in the fair value hierarchy $ 80 $ 36 $ - 116  Total assets measured at net asset value (c) 25  Total fair value of plan assets $ 141 _____________ (a) Substantially all corporate bonds are rated investment grade by Fitch, Moody’s or S&P. (b) Other consists primarily of diversified bond mutual funds. (c) Fair value was measured using the net asset value (NAV) per share as a practical expedient as the investments did not have a readily determinable fair value and are not required to be classified in the fair value hierarchy. The NAV fair value amounts presented here are intended to permit a reconciliation to the total fair value of plan assets.  Expected Long-Term Rate of Return on Assets Assumption  The retirement plans’ strategic asset allocation is determined in conjunction with the plans’ advisors and utilizes a comprehensive Asset-Liability modeling approach to evaluate potential long-term outcomes of various investment strategies. The modeling incorporates long-term rate of return assumptions for each asset class based on historical and future expected asset class returns, current market conditions, rate of inflation, current prospects for economic growth, and taking into account the diversification benefits of investing in multiple asset classes and potential benefits of employing active investment management.     Pension Plans Oncor OPEB Plans  Asset Class Expected Long-Term Rate of Return Asset Class Expected Long-Term Rate of Return   International equity securities 7.58% 401(h) accounts 5.59%  U.S. equity securities 6.50% Life insurance VEBA 5.10%  Real estate 5.60% Union VEBA 5.10%  Credit strategies 3.90% Non-union VEBA 1.10%  Fixed income securities 2.32% Shared retiree VEBA 1.10%  Weighted average (a) 4.57% Weighted average 5.24% _____________ (a) The 2021 expected long-term rate of return for the nonregulated portion of the Oncor Retirement Plan is 3.75% , an d for Oncor’s obligations with respect to the Vistra Retirement Plan is 4.20% .  Significant Concentrations of Risk  The plans’ investments are exposed to risks such as interest rate, capital market and credit risks. We seek to optimize return on investment consistent with levels of liquidity and investment risk which are prudent and reasonable, given prevailing capital market conditions and other factors specific to participating employers. While we recognize the importance of return, investments will be diversified in order to minimize the risk of large losses unless, under the circumstances, it is clearly prudent not to do so. There are also various restrictions and guidelines in place including limitations on types of investments allowed and portfolio weightings for certain investment securities to assist in the mitigation of the risk of large losses.  Assumed Discount Rate  For the Oncor retirement plans at December 31, 2020, we selected the assumed discount rate using the Aon AA-AAA Bond Universe yield curve, which is based on corporate bond yields and at December 31, 2020 consisted of 862 corporate bonds with an average rating of AA and AAA using Moody’s, S&P and Fitch ratings. For Oncor’s obligations with respect to the Vistra Retirement Plan and the Oncor OPEB Plans at December 31, 2020, we selected the assumed discount rate using the Aon AA Above Median yield curve, which is based on corporate bond yields and at December 31, 2020 consisted of 305 corporate bonds with an average rating of AA using Moody’s, S&P and Fitch ratings.  Pension and Oncor OPEB Plans Cash Contributions  Our contributions to the benefit plans were as follows:    Year Ended December 31,  2020 2019 2018   Pension plans contributions $ 134 $ 41 $ 82  Oncor OPEB Plans contributions 35 35 41  Total contributions $ 169 $ 76 $ 123  Our funding for the pension plans and the Oncor OPEB Plans is expected to total $24 million and $35 million , respectively in 2021 and approximately $560 million and $176 million , respectively, in the five-year period 2021 to 2025.  Future Benefit Payments  Estimated future benefit payments to participants are as follows:    2021 2022 2023 2024 2025 2026-30   Pension plans $ 186 $ 189 $ 192 $ 195 $ 197 $ 975  Oncor OPEB Plans $ 49 $ 51 $ 52 $ 53 $ 54 $ 271  Thrift Plan  Our employees are eligible to participate in a qualified savings plan, the Oncor Thrift Plan, which is a participant-directed defined contribution plan subject to the provisions of ERISA and intended to qualify under Section 401(a) of the Code, and to meet the requirements of Code Sections 401(k) and 401(m). Under the plan, employees may contribute, through pre-tax salary deferrals and/or after-tax applicable payroll deductions, a portion of their regular salary or wages as permitted under law. Employer matching contributions are made in an amount equal to 100% of the first 6% of employee contributions for employees who are covered under the Cash Balance Formula of the Oncor Retirement Plan, and 75% of the first 6% of employee contributions for employees who are covered under the Traditional Retirement Plan Formula of the Oncor Retirement Plan. Employer matching contributions are made in cash and may be allocated by participants to any of the plan’s investment options. Our contributions to the Oncor Thrift Plan totaled $23 million , $20 million and $19 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Stock-Based Compensation [Abstract]
STOCK-BASED COMPENSATION	10. STOCK-BASED COMPENSATION  We currently do not offer stock-based compensation to our employees or directors. In 2008 and 2009, we established stock appreciation rights (SARs) plans under which certain of our executive officers, key employees and non-employee members of our board of directors were granted SARs payable in cash, or in some circumstances, Oncor membership interests.  In November 201 2, we accepted the early exercise for cash payments of all outstanding SARs (both vested and unvested) issued to date pursuant to both SARs plans. As part of the 2012 early exercise of SARs we began accruing interest on dividends declared with respect to the SARs. Under both SARs plans, dividends that were paid in respect of Oncor membership interests while the SARs were outstanding were credited to the SARs holder’s account as if the SARs were units, payable upon the earliest to occur of death, disability, separation from service, unforeseeable emergency, a change in control, or the occurrence of an event triggering SAR exercisability . As a result of the Sempra Acquisition, the dividend and interest accounts were distributed in 2018, totaling $15 million . For accounting purposes, the liability was discounted based on an employee’s or director’s expected retirement date . We recognized $4 million in accretion and interest with respect to such dividend and interest accounts in 2018. No SARs liability remained at December 31, 2020 and 2019 . 

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2020
Related-Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	11. RELATED-PARTY TRANSACTIONS  The following represent our significant related-party transactions and related matters.  · We are not a member of another entity’s consolidated tax group, but our owners’ federal income tax returns include their portion of our results. Under the terms of a tax sharing agreement among us, Oncor Holdings, Texas Transmission and STH, we are generally obligated to make payments to our owners, pro rata in accordance with their respective membership interests, in an aggregate amount that is substantially equal to the amount of federal income taxes that we would have been required to pay if we were filing our own corporate income tax return. STH will file a combined Texas margin tax return which includes our results and our share of Texas margin tax payments, which are accounted for as income taxes and calculated as if we were filing our own return. See discussion in Note 1 under “Provision in Lieu of Income Taxes.” Under the “in lieu of” tax concept, all in lieu of tax assets and tax liabilities represent amounts that will eventually be settled with our members. In the event such amounts are not paid under the tax sharing agreement, it is probable that this regulatory liability will continue to be included in Oncor’s rate setting processes.  Amounts payable to (receivable from) members related to income taxes under the agreement and reported on our balance sheet consisted of the following:    At December 31, 2020 At December 31, 2019  STH Texas Transmission Total STH Texas Transmission Total   Federal income taxes payable (receivable) $ (6) $ (1) $ (7) $ (2) $ (1) $ (3)  Texas margin tax payable 23 - 23 22 - 22  Net payable (receivable) $ 17 $ (1) $ 16 $ 20 $ (1) $ 19  Cash payments made to (received from) members related to income taxes consisted of the following:    Year Ended December 31,  2020 2019 2018  STH Texas Transm. Total STH Texas Transm. Total STH EFH Corp. Texas Transm. Total   Federal income taxes $ 70 $ 17 $ 87 $ 45 $ 11 $ 56 $ 59 $ (19) $ 10 $ 50  Texas margin taxes 22 - 22 22 - 22 21 - - 21  Total payments (receipts) $ 92 $ 17 $ 109 $ 67 $ 11 $ 78 $ 80 $ (19) $ 10 $ 71  · As of March 8, 2018, approximately 16% of the equity in an existing vendor of the company was owned by a member of the Sponsor Group. As a result of the Sempra Acquisition, the Sponsor Group ceased to be a related party as of March 9, 2018. During 2018, this vendor performed transmission and distribution system construction and maintenance services for us. Cash payments were made for such services to this vendor and/or its subsidiaries totaling $35 million for the year-to-date period ended March 8, 2018, of which approximately $33 million was capitalized and $2 million was recorded as an operation and maintenance expense.  · Sempra acquired an indirect 50 % interest in Sharyland Holdings, L.P., the parent of Sharyland, in the Sempra-Sharyland Transaction. As a result of the Sempra-Sharyland Transaction, Sharyland is now our affiliate for purposes of PUCT rules. Pursuant to the PUCT order in Docket No. 48929 approving the InfraREIT Acquisition, upon closing of the InfraREIT Acquisition we entered into an operation agreement pursuant to which we will provide certain operations services to Sharyland at cost with no markup or profit. Sharyland provided wholesale transmission service to us in the amount of $13 million and $9 million in the year ended December 31, 2020 and in the period between the May 16, 2019 InfraREIT Acquisition date through December 31, 2019, respectively. We provided substation monitoring and switching service to Sharyland in the amount of $629,000 and $303,000 in the year ended December 31, 2020 and in the period between the May 16, 2019 InfraREIT Acquisition date through December 31, 2019, respectively.  · We paid Sempra $119,000 and $ 109,000 for the years ended December 31, 2020 and 2019, respectively for tax work.  See Notes 1, 4, and 8 for information regarding the tax sharing agreement and distributions to members.

Supplementary Financial Informa

Supplementary Financial Information	12 Months Ended
	Dec. 31, 2020
Supplementary Financial Information [Abstract]
SUPPLEMENTARY FINANCIAL INFORMATION	12. SUPPLEMENTARY FINANCIAL INFORMATION  Other Deductions and (Income)      Year Ended December 31,  2020 2019 2018   Professional fees $ 6 $ 10 $ 12  Sempra Acquisition related costs - - 12  InfraREIT Acquisition related costs - 9 -  Recoverable Pension and OPEB - non-service costs 55 57 53  Non-recoverable pension and OPEB 4 4 6  AFUDC equity income (29) (10) -  Interest income (4) (5) (1)  Other 1 (2) 2  Total other deductions and (income) - net $ 33 $ 63 $ 84  Interest Expense and Related Charges   Year Ended December 31,  2020 2019 2018   Interest $ 413 $ 382 $ 358  Amortization of debt issuance costs and discounts 11 9 6  Less AFUDC – capitalized interest portion (19) (16) (13)  Total interest expense and related charges $ 405 $ 375 $ 351  Trade Accounts and Other Receivables  Trade accounts and other receivables reported on our balance sheet consisted of the following:    At December 31,  2020 2019   Gross trade accounts and other receivables $ 767 $ 666  Allowance for uncollectible accounts (7) (5)  Trade accounts receivable – net $ 760 $ 661  At December 31, 2020, REP subsidiaries of two of our largest customers represented 21% and 15% of the trade accounts receivable balance and n o other customers represented 10% or more of the trade accounts receivable balance. A t December 31, 2019, REP subsidiaries of two of our largest customers represented 15% and 11% of the trade accounts receivable balance.  Under a PUCT rule relating to the Certification of Retail Electric Providers, write-offs of uncollectible amounts owed by REPs are deferred as a regulatory asset.  Investments and Other Property  Investments and other property reported on our balance sheet consist of the following:   At December 31,  2020 2019   Assets related to employee benefit plans $ 124 $ 119  Land 16 12  Other 2 2  Total investments and other property $ 142 $ 133  The majority of these assets represent cash surrender values of life insurance policies that are purchased to fund liabilities under deferred compensation plans. At December 31, 2020 and 2019, the face amount of these policies totaled $181 million and $172 million , respectively, and the net cash surrender values (determined using a Level 2 valuation technique) totaled $97 million and $95 million at December 31, 2020 and 2019, respectively. Changes in cash surrender value are netted against premiums paid. Other investment assets held to satisfy deferred compensation liabilities are recorded at market value.  Property, Plant and Equipment  Property, plant and equipment reported on our balance sheet consisted of the following:    Composite Depreciation Rate/ At December 31,  Avg. Life at December 31, 2020 2020 2019  Assets in service:  Distribution 2.5% / 39.4 years $ 14,937 $ 14,007  Transmission 2.9% / 34.8 years 12,156 11,094  Other assets 6.7% / 14.9 years 1,855 1,648  Total 28,948 26,749  Less accumulated depreciation 8,336 7,986  Net of accumulated depreciation 20,612 18,763  Construction work in progress 593 585  Held for future use 20 22  Property, plant and equipment – net $ 21,225 $ 19,370  Depreciation expense as a percent of average depreciable property approximated 2.7% , 2.7% and 2.8% for the years ended December 31, 2020, 2019 and 2018, respectively.  Intangible Assets  Intangible assets (other than goodwill) reported on our balance sheet as part of property, plant and equipment consisted of the following:   At December 31, 2020 At December 31, 2019  Gross Gross  Carrying Accumulated Carrying Accumulated  Amount Amortization Net Amount Amortization Net  Identifiable intangible assets subject to amortization:  Land easements $ 623 $ 112 $ 511 $ 575 $ 107 $ 468  Capitalized software 1,027 484 543 933 430 503  Total $ 1,650 $ 596 $ 1,054 $ 1,508 $ 537 $ 971  A ggregate amortization expense for intangible assets totaled $62 million , $52 million and $50 million for the years ended December 31, 2020, 2019 and 2018, respectively. At December 31, 2020, the weighted average remaining useful lives of capitalized land easements and software were 84 years and 9 years, respectively. The estimated aggregate amortization expense for each of the next five fiscal years is as follows:   Year Amortization Expense   2021 $ 68  2022 68  2023 68  2024 67  2025 67  Goodwill totaling $ 4.740 billion was reported on our balance sheet at both December 31, 2020 and 2019. See Note 1 regarding goodwill impairment assessment and testing.  Operating Lease, Third-Party Joint Project and Other Obligations  Operating lease, third-party joint project and other obligations reported on our balance sheet consisted of the following:   At December 31,  2020 2019   Operating lease liabilities (Notes 1 and 7) $ 124 $ 66  Investment tax credits 5 6  Third-party joint project obligation (Note 1) (a) 100 4  Other 76 70  Total operating lease, third-party joint project and other obligations $ 305 $ 146 ____________ (a) Oncor is currently involved in a joint project with LP&L. See Note 3 for more information.  Supplemental Cash Flow Information   Year Ended December 31,  2020 2019 2018  Cash payments (receipts) related to:   Interest $ 406 $ 368 $ 368  Less capitalized interest (19) (16) (13)  Interest payments (net of amounts capitalized) $ 387 $ 352 $ 355   Amount in lieu of income taxes (a):  Federal $ 87 $ 56 $ 50  State 22 22 21  Total payments (receipts) in lieu of income taxes $ 109 $ 78 $ 71   Noncash increase in operating lease obligation for ROU assets $ 72 $ 38 $ -   Noncash investing and financing activity:   Acquisition (b):  Assets acquired $ - $ 2,547 $ -  Liabilities assumed - (1,223) -  Cash paid $ - $ 1,324 $ -   Debt exchange (c):  Debt issued in debt exchange offering $ 300 $ - $ -  Debt exchanged in debt exchange offering (300) - -  $ - $ - $ -   Noncash construction expenditures (d) $ 254 $ 278 $ 174 ______________ (a) See Note 11 for income tax related detail. (b) See Note 13 for more information on noncash debt exchanges related to InfraREIT Acquisition. (c) See Note 6 for more information on noncash debt exchanges related to 2052 Notes issuance. (d) Represents end-of-period accruals.  Quarterly Information (unaudited)  Results of operations by quarter for the years ended December 31, 2020 and 2019 are summarized below. In our opinion, all adjustments (consisting of normal recurring accruals) necessary for a fair statement of such amounts have been made. Quarterly results are not necessarily indicative of a full year’s operations because of seasonal and other factors.    2020 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 1,072 $ 1,090 $ 1,232 $ 1,117  Operating income 242 285 362 250  Net income 131 176 258 148   2019 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 1,016 $ 1,041 $ 1,211 $ 1,079  Operating income 216 253 369 236  Net income 116 139 263 133 

Acquisition Activity

Acquisition Activity	12 Months Ended
	Dec. 31, 2020
Acquisition Activity [Abstract]
Acquisition Activity	13. ACQUISITION ACTIVITY  InfraREIT Acquisition  In May 201 9, we completed the InfraREIT Acquisition, pursuant to which we acquired all of the equity interests of InfraREIT and its subsidiary, InfraREIT Partners for a total cash consideration of $1.275 billion . In addition , we paid certain transaction costs incurred by InfraREIT (including a management agreement termination fee of $40 million that InfraREIT paid an affiliate of Hunt Consolidated, Inc. at closing), with the aggregate cash consideration and payment of InfraREIT expenses totaling $1.324 billion . We funded the cash consideration and certain transaction expenses with capital contributions in an aggregate amount of $1.330 billion received from Sempra and certain indirect equity holders of Texas Transmission.  In connection with and immediately following the closing of the InfraREIT Acquisition, In May 201 9, we extinguished all $953 million outstanding principal amount of debt of InfraREIT and its subsidiaries through repaying $602 million principal amount of InfraREIT subsidiary debt and exchanging new Oncor senior secured debt for $351 million principal amount of InfraREIT subsidiary debt.  As a result of the InfraREIT Acquisition, which included the exchange of certain assets between SDTS and SU pursuant to the SDTS-SU Asset Exchange, we acquired our indirect subsidiary NTU and expanded our existing footprint in Texas by adding various electricity transmission and distribution assets and projects in the north, central, west and panhandle regions of Texa s, including a joint project with LP&L for the build out and associated station work to join most of the City of Lubbock’s electric facilities to the ERCOT market. For more information on the LP&L joint project, see Note 3.  Business Combination Accounting  We accounted for the InfraREIT Acquisition as a business acquisition with identifiable assets acquired and liabilities assumed recorded at their estimated fair values on the closing date. The combined results of operations are reported in our consolidated financial statements beginning as of the closing date. A summary of techniques used to estimate the preliminary fair value of the identifiable assets and liabilities is listed below.  · Assets and liabilities that are included in the PUCT cost-based regulatory rate-setting processes are recorded at fair values equal to their regulatory carrying value consistent with GAAP and industry practice. · Working capital was valued using market information (Level 2).  The following tables set forth the purchase price paid. The final purchase price allocation was completed as of March 31, 2020.   Purchase of outstanding InfraREIT shares and units $ 1,275  Certain transaction costs of InfraREIT paid by Oncor through June 30, 2019 (a) 53  Total purchase price paid through June 30, 2019 1,328  Adjustments made in the period from June 30, 2019 through March 31, 2020 (4)  Total purchase price paid $ 1,324 ________________ (a) Represents certain transaction costs incurred by InfraREIT in connection with the transaction and paid by Oncor, including a $40 million management termination fee payable to an affiliate of Hunt Consolidated, Inc.    Purchase price allocation is as follows:  As of May 16, 2019  Assets acquired:  Current assets $ 45  Property, plant and equipment - net 1,800  Goodwill 676  Regulatory assets 16  Other noncurrent assets 10  Total assets acquired 2,547   Liabilities assumed:  Short-term debt 115  Other current liabilities 24  Regulatory liabilities 148  Liability in lieu of deferred income taxes 97  Long-term debt, including due currently 839  Total liabilities assumed 1,223  Net assets acquired 1,324  Total purchase price paid $ 1,324  The goodwill of $676 million arising from the InfraREIT Acquisition is attributable to the assets acquired, which expand our transmission footprint and help us support ERCOT market growth. None of the goodwill is recoverable nor provides a tax benefit in the rate-making process. We did not assume any employee benefit obligations in the acquisition.  Acquisition costs incurred in the InfraREIT Acquisition by Oncor and recorded to other deductions totaled zero in 2020 and $9 million in 2019. Our statements of consolidated income include revenues and net income of the acquired business totaling $250 million and $106 million in 2020 and $156 million and $58 million in 2019, respectively.  Unaudited Pro Forma Financial Information  The following unaudited pro forma financial information for the years ended December 31, 2019 and 2018 assumes that the InfraREIT Acquisition occurred on January 1, 2018. The unaudited pro forma financial information is provided for information purposes only and is not necessarily indicative of the results of operations that would have occurred had the InfraREIT Acquisition been completed on January 1, 2018, nor is the unaudited pro forma financial information indicative of future results of operations, which may differ materially from the pro forma financial information presented here.     Year Ended December 31,  2019 2018  Oncor Consolidated Pro Forma Revenues $ 4,431 $ 4,318  The unaudited pro forma financial information above excludes pro forma earnings due to the impracticability of a calculation. The acquiree previously operated under a real estate investment trust structure with a unique cost structure and unique federal tax attributes. An accurate retrospective application cannot be objectively and reliably calculated as the new cost structure and new tax attributes would require a significant amount of estimates and judgments.

Description Of Business And S_2

Description Of Business And Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Description Of Business And Significant Accounting Policies [Abstract]
Description Of Business	Description of Business  References in this report to “we,” “our,” “us” and “the company” are to Oncor and/or its subsidiaries as apparent in the context. See “Glossary” for definition of terms and abbreviations.  We are a regulated electricity transmission and distribution company principally engaged in providing delivery services to REPs that sell power in the north-central, eastern, western and panhandle regions of Texas. We are a direct, majority-owned subsidiary of Oncor Holdings, which is indirectly and wholly owned by Sempra. Oncor Holdings owns 80.25% of our membership interests and Texas Transmission owns 19.75% of our membership interests. We are managed as an integrated business; consequently, there are no separate reportable business segments.  Our consolidated financial statements includes the results of our wholly owned indirect subsidiary, NTU, which we acquired as part of the InfraREIT Acquisition that closed on May 16, 2019. NTU is a regulated utility that primarily provides electricity transmission delivery service in the north-central, western and panhandle regions of Texas. 
Ring-Fencing Measures	Ring-Fencing Measures  Since 2007, various ring-fencing measures have been taken to enhance our credit quality and the separateness between the Oncor Ring-Fenced Entities and entities with ownership interests in Oncor or Oncor Holdings. These ring-fencing measures serve to mitigate the Oncor Ring-Fenced Entities’ credit exposure to owners of Oncor and Oncor Holdings, and to reduce the risk that the assets and liabilities of Oncor Ring-Fenced Entities would be substantively consolidated with the assets and liabilities of any direct or indirect owners of Oncor and Oncor Holdings in connection with a bankruptcy of any such entities. These measures include the November 200 8 sale of 19.75% of Oncor’s equity interests to Texas Transmission.  In March 201 8, Sempra indirectly acquired Oncor Holdings through the Sempra Acquisition. The Sempra Acquisition was consummated after obtaining the approval of the bankruptcy court in the EFH Bankruptcy Proceedings and the PUCT. The PUCT approval was obtained in Docket No. 47675, and the final order issued in that docket (Sempra Order) outlines certain ring-fencing measures, governance mechanisms and restrictions that apply after the Sempra Acquisition. As a result of these ring-fencing measures, Sempra does not control Oncor, and the ring-fencing measures limit Sempra’s ability to direct the management, policies and operations of Oncor, including the deployment or disposition of Oncor’s assets, declarations of dividends, strategic planning and other important corporate issues and actions.  None of the assets of the Oncor Ring-Fenced Entities are available to satisfy the debt or obligations of any Sempra entity or any other direct or indirect owner of Oncor or Oncor Holdings. The assets and liabilities of the Oncor Ring-Fenced Entities are separate and distinct from those of any Sempra entities and any other direct or indirect owner of Oncor or Oncor Holdings. We do not bear any liability for debt or contractual obligations of Sempra and its affiliates or any other direct or indirect owner of Oncor or Oncor Holdings, and vice versa. Accordingly, our operations are conducted, and our cash flows are managed, independently from Sempra and its affiliates and any other direct or indirect owner of Oncor or Oncor Holdings.  Oncor is a limited liability company governed by a board of directors, not its members. The Sempra Order and our Limited Liability Company Agreement require that the board of directors of Oncor consist of thirteen members, constituted as follows:  · seven Disinterested Directors, who (i) shall be independent directors in all material respects under the rules of the New York Stock Exchange in relation to Sempra or its subsidiaries and affiliated entities and any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, and (ii) shall have no material relationship with Sempra or its subsidiaries or affiliated entities or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, currently or within the previous ten years; · two members designated by Sempra (through Oncor Holdings); · two members designated by Texas Transmission; and · two current or former officers of Oncor (the Oncor Officer Directors), currently Robert S. Shapard and E. Allen Nye, Jr., who are our Chairman of the Board and Chief Executive, respectively.  Until March 9, 2028, in order for a current or former officer of Oncor to be eligible to serve as an Oncor Officer Director, the officer cannot have worked for Sempra or any of its affiliates (excluding Oncor Holdings and Oncor) or any other entity with a direct or indirect ownership interest in Oncor or Oncor Holdings in the ten-year period prior to serving as an Oncor Officer Director. Oncor Holdings, at the direction of STIH, has the right to nominate and/or seek the removal of the Oncor Officer Directors, subject to approval by a majority of the Oncor board of directors. STIH is a wholly owned indirect subsidiary of, and controlled by, Sempra following the Sempra Acquisition.  In addition, the Sempra Order provides that Oncor’s board of directors cannot be overruled by the board of Sempra or any of its subsidiaries on dividend policy, the issuance of dividends or other distributions (except for contractual tax payments), debt issuance, capital expenditures, operation and maintenance expenditures, management and service fees, and appointment or removal of board members, provided that certain actions may also require the additional approval of the Oncor Holdings board of directors. The Sempra Order also provides that any changes to the size, composition, structure or rights of the board must first be approved by the PUCT. In addition, if Sempra acquires Texas Transmission’s interest in Oncor, the two board positions on Oncor’s board of directors that Texas Transmission is entitled to appoint will be eliminated and the size of Oncor’s board of directors will be reduced by two.  Additional regulatory commitments, governance mechanisms and restrictions provided in the Sempra Order and our Limited Liability Company Agreement to ring-fence Oncor from its owners include, among others:  · A majority of the Disinterested Directors of Oncor and the directors designated by Texas Transmission that are present and voting (of which at least one must be present and voting) must approve any annual or multi-year budget if the aggregate amount of capital expenditures or operating and maintenance expenditures in such budget is more than a 10% increase or decrease from the corresponding amounts of such expenditures in the budget for the preceding fiscal year or multi-year period, as applicable; · Oncor may not pay any dividends or make any other distributions (except for contractual tax payments) if a majority of its Disinterested Directors or either of the two directors appointed by Texas Transmission determines that it is in the best interests of Oncor to retain such amounts to meet expected future requirements; · At all times, Oncor will remain in compliance with the debt-to-equity ratio established by the PUCT from time to time for ratemaking purposes, and Oncor will not pay dividends or other distributions (except for contractual tax payments), if that payment would cause its debt-to-equity ratio to exceed the debt-to-equity ratio approved by the PUCT; · If the credit rating on Oncor’s senior secured debt by any of the three major rating agencies falls below BBB (or the equivalent), Oncor will suspend dividends and other distributions (except for contractual tax payments), unless otherwise allowed by the PUCT; · Without the prior approval of the PUCT, neither Sempra nor any of its affiliates (excluding Oncor) will incur, guaranty or pledge assets in respect of any indebtedness that is dependent on the revenues of Oncor in more than a proportionate degree than the other revenues of Sempra or on the membership interests of Oncor, and there will be no debt at STH or STIH at any time following the closing of the Sempra Acquisition; · Neither Oncor nor Oncor Holdings will lend money to or borrow money from Sempra or any of its affiliates (other than Oncor subsidiaries), or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, and neither Oncor nor Oncor Holdings will share credit facilities with Sempra or any of its affiliates (other than Oncor subsidiaries), or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings; · There must be maintained certain “separateness measures” that reinforce the legal and financial separation of Oncor from its owners, including a requirement that dealings between Oncor, Oncor Holdings and their subsidiaries with Sempra, any of Sempra’s other affiliates or any entity with a direct or indirect ownership interest in Oncor or Oncor Holdings, must be on an arm’s-length basis, limitations on affiliate transactions, separate recordkeeping requirements and a prohibition on Sempra or its affiliates pledging Oncor assets or membership interests for any entity other than Oncor; and · Sempra will continue to hold indirectly at least 51% of the ownership interests in Oncor and Oncor Holdings for at least five years following the closing of the Sempra Acquisition, unless otherwise specifically authorized by the PUCT.
Basis Of Presentation	Basis of Presentation  Our consolidated financial statements have been prepared in accordance with GAAP governing rate-regulated operations. All dollar amounts in the financial statements and tables in the notes are stated in millions of U.S. dollars unless otherwise indicated.
Use Of Estimates	Use of Estimates  Preparation of our financial statements requires management to make estimates and assumptions about future events that affect the reporting of assets and liabilities at the balance sheet dates and the reported amounts of revenue and expense, including fair value measurements. In the event estimates and/or assumptions prove to be different from actual amounts, adjustments are made in subsequent periods to reflect more current information. No material adjustments were made to previous estimates or assumptions during the current year.
Revenue Recognition	Revenue Recognition  Oncor’s revenue is billed under tariffs approved by the PUCT and the majority of revenues are related to providing electric delivery service to consumers. Tariff rates are designed to recover the cost of providing electric delivery service including a reasonable rate of return on invested capital. Revenues are generally recognized when the underlying service has been provided in an amount prescribed by the related tariff. See Note 3 for additional information regarding revenues.
Provision In Lieu Of Income Taxes	Provision in Lieu of Income Taxes  Our tax sharing agreement with Oncor Holdings, Texas Transmission and STH provides for the calculation of amounts related to income taxes for each of Oncor Holdings and Oncor substantially as if these entities were taxed as corporations and requires payments to the members determined on that basis (without duplication for any income taxes paid by a subsidiary of Oncor Holdings).  We are a partnership for U.S. federal income tax purposes. Accordingly, while partnerships are not subject to income taxes, in consideration of the presentation of our financial statements as an entity subject to cost-based regulatory rate-setting processes, with such costs historically including income taxes, the financial statements present amounts determined under the tax sharing agreement as “provision in lieu of income taxes” and “liability in lieu of deferred income taxes”. Such amounts are determined in accordance with the provisions of the accounting guidance for income taxes and accounting standards that provide interpretive guidance for accounting for uncertain tax positions and thus differences between the book and tax bases of assets and liabilities are accounted for as if we were a stand-alone corporation. In the event such amounts are not paid under the tax sharing agreement, it is probable that this regulatory liability will continue to be included in Oncor’s rate setting processes.  We classify any interest and penalties expense related to uncertain tax positions as current provision in lieu of income taxes as discussed in Note 4.
Defined Benefit Pension Plans And OPEB Plans	Defined Benefit Pension Plans and Oncor OPEB Plans  We have liabilities under pension plans that offer benefits based on either a traditional defined benefit formula or a cash balance formula and Oncor OPEB plans that offer certain health care and life insurance benefits to eligible employees and their eligible dependents upon the retirement of such employees. Costs of pension and Oncor OPEB plans are dependent upon numerous factors, assumptions and estimates. See Note 9 for additional information regarding pension and OPEB plans.
System Of Accounts	System of Accounts  Our accounting records have been maintained in accordance with the FERC Uniform System of Accounts as adopted by the PUCT.
Property, Plant And Equipment	Property, Plant and Equipment  Properties are stated at original cost. The cost of self-constructed property additions includes materials and both direct and indirect labor and applicable overhead and an allowance for funds used during construction.  D epreciation of property, plant and equipment is calculated on a straight-line basis over the estimated service lives of the properties based on depreciation rates approved by the PUCT. As is common in the industry, depreciation expense is recorded using composite depreciation rates that reflect blended estimates of the lives of major asset groups as compared to depreciation expense calculated on a component asset-by-asset basis. Depreciation rates include plant removal costs as a component of depreciation expense, consistent with regulatory treatment. Actual removal costs incurred are charged to accumulated depreciation. Accrued removal costs in excess of incurred removal costs are reclassified as a regulatory liability to retire assets in the future.
Regulatory Assets And Liabilities	Regulatory Assets and Liabilities  We are subject to rate regulation and our financial statements reflect regulatory assets and liabilities in accordance with accounting standards related to the effect of certain types of regulation. Regulatory assets and liabilities represent probable future revenues that will be recovered from or refunded to customers through the ratemaking process based on PURA and/or the PUCT’s orders, precedents or substantive rules. Rate regulation is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital subject to PUCT review for reasonableness. Regulatory decisions can have an impact on the recovery of costs, the rate earned on invested capital and the timing and amount of assets to be recovered by rates. See Note 2 for more information regarding regulatory assets and liabilities. 
Franchise Taxes	 Franchise Taxes  Franchise taxes are assessed to us by local governmental bodies, based on kWh delivered and are a principal component of taxes other than amounts related to income taxes as reported in the income statement. Franchise taxes are not a “pass through” item. The rates we charge customers are intended to recover the franchise taxes, but we are not acting as an agent to collect the taxes from customers.
Allowance For Funds Used During Construction (AFUDC)	Allowance for Funds Used During Construction (AFUDC)  AFUDC is a regulatory cost accounting procedure whereby both interest charges on borrowed funds and a return on equity capital used to finance construction are included in the recorded cost of utility plant and equipment being constructed. AFUDC is capitalized on all projects involving construction periods lasting greater than thirty days. The interest portion of capitalized AFUDC is accounted for as a reduction to interest expense and the equity portion of capitalized AFUDC is accounted for as other income. See Note 12 for detail of amounts reducing interest expense and increasing other income.
Cash And Cash Equivalents	Cash and Cash Equivalents  For purposes of reporting cash and cash equivalents, highly liquid investments with original maturities of three months or less at the date of purchase are considered to be cash equivalents.
Fair Value Of Nonderivative Financial Instruments	Fair Value of Nonderivative Financial Instruments  The carrying amounts for financial assets classified as current assets and the carrying amounts for financial liabilities classified as current liabilities approximate fair value due to the short maturity of such instruments. The fair values of other financial instruments, for which carrying amounts and fair values have not been presented, are not materially different than their related carrying amounts. The following discussion of fair value accounting standards applies primarily to our determination of the fair value of assets in the pension and Oncor OPEB plans’ trusts (see Note 9) and long-term debt (see Note 6).  Accounting standards related to the determination of fair value define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We use a “mid-market” valuation convention (the mid-point price between bid and ask prices) as a practical expedient to measure fair value for the majority of our assets and liabilities subject to fair value measurement on a recurring basis. We primarily use the market approach for recurring fair value measurements and use valuation techniques to maximize the use of observable inputs and minimize the use of unobservable inputs.  We categorize our assets and liabilities recorded at fair value based upon the following fair value hierarchy:  · Level 1 valuations use quoted prices in active markets for identical assets or liabilities that are accessible at the measurement date. An active market is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. · Level 2 valuations use inputs that, in the absence of actively quoted market prices, are observable for the asset or liability, either directly or indirectly. Level 2 inputs include: (a) quoted prices for similar assets or liabilities in active markets , (b) quoted prices for identical or similar assets or liabilities in markets that are not active, (c) inputs other than quoted prices that are observable for the asset or liability such as interest rates and yield curves observable at commonly quoted intervals and (d) inputs that are derived principally from or corroborated by observable market data by correlation or other means. Our Level 2 valuations utilize over-the-counter broker quotes, quoted prices for similar assets or liabilities that are corroborated by correlations or other mathematical means and other valuation inputs. · Level 3 valuations use unobservable inputs for the asset or liability. Unobservable inputs are used to the extent observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. We use the most meaningful information available from the market combined with internally developed valuation methodologies to develop our best estimate of fair value.  We utilize several different valuation techniques to measure the fair value of assets and liabilities, relying primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities for those items that are measured on a recurring basis.  The fair value of certain investments is measured using the net asset value (NAV) per share as a practical expedient. Such investments measured at NAV are not required to be categorized within the fair value hierarchy.
Derivative Instruments And Mark-to-Market Accounting	Derivative Instruments and Mark-to-Market Accounting  From time-to-time we enter into derivative instruments to hedge interest rate risk. If the instrument meets the definition of a derivative under accounting standards related to derivative instruments and hedging activities, the fair value of each derivative is recognized on the balance sheet as a derivative asset or liability and changes in the fair value are recognized in net income, unless criteria for cash flow hedge accounting are met. This recognition is referred to as “mark-to-market” accounting. 
Impairment Of Long-Lived Assets And Goodwill	Impairment of Long-Lived Assets and Goodwill  We evaluate long-lived assets (including intangible assets with finite lives) for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We also evaluate goodwill for impairment annually on October 1 and whenever events or changes in circumstances indicate that an impairment may exist. The determination of the existence of these and other indications of impairment involves judgments that are subjective in nature and may require the use of estimates in forecasting future results and cash flows.  For our annual goodwill impairment testing, we have the option to first make a qualitative assessment of whether it is more likely than not that our enterprise fair value is less than our enterprise carrying amount before applying the quantitative goodwill impairment test. If we elect to perform the qualitative assessment, we evaluate relevant events and circumstances, including but not limited to, macroeconomic conditions, industry and market considerations, cost factors and the overall financial performance. If, after assessing these qualitative factors, we determine that it is more-likely-than-not that our enterprise fair value is less than our enterprise carrying amount, then we perform a quantitative goodwill impairment test. If, after performing the quantitative goodwill impairment test, we determine that goodwill is impaired, we record the amount of goodwill impairment as the excess of carrying amount over fair value, not to exceed the carrying amount of goodwill.  In each of 2020, 2019 and 2018, we concluded, based on a qualitative assessment, that our estimated enterprise fair value was more likely than not greater than our carrying value. As a result , no quantitative goodwill impairment tests were required and n o impairments were recognized .
Changes In Accounting Standards	Changes in Accounting Standards  Topic 326, “Financial Instruments—Credit Losses” – In June 201 6, the FASB issued ASU No. 2016-13, which changes how entities account for credit losses on receivables and certain other financial assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards. We adopted the new standard effective January 1, 2020. The adoption of the new standard did not have a material impact on our consolidated financial statements.  Topic 848, “Facilitation of the Effects of Reference Rate Reform on Financial Reporting” – In March 202 0, the FASB issued ASU No. 2020-04, which provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. ASU No. 2020-04 is effective for all entities as of March 12, 2020 through December 31, 2022. The standard allows entities to account for contract modifications as an event that does not require reassessment or remeasurement (i.e., as a continuation of the existing contract). Our Credit Facility use s LIBOR as a benchmark for establishing interest rates. Implementation has not had an impact on our consolidated financial statements. In the event we modify our Credit Facility related to the phase-out of LIBOR, we will evaluate the optional expedients and exceptions under the standard.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2020
Regulatory Matters [Abstract]
Components Of Regulatory Assets And Liabilities	  Remaining Rate Recovery/Amortization Period at At December 31,  December 31, 2020 2020 2019   Regulatory assets:  Employee retirement liability (a)(b)(c) To be determined $ 672 $ 623  Employee retirement costs being amortized 7 years 227 262  Employee retirement costs incurred since the last rate review period (b) To be determined 67 79  Self-insurance reserve (primarily storm recovery costs) being amortized 7 years 266 309  Self-insurance reserve incurred since the last rate review period (primarily storm related) (b) To be determined 256 238  Debt reacquisition costs Lives of related debt 25 29  Under-recovered AMS costs 7 years 149 170  Energy efficiency performance bonus (a) 1 year or less 14 9  Wholesale distribution substation service To be determined 55 34  Unrecovered expenses related to COVID-19 (d) To be determined 27 -  Other regulatory assets Various 21 22  Total regulatory assets 1,779 1,775   Regulatory liabilities:  Estimated net removal costs Lives of related assets 1,262 1,178  Excess deferred taxes Primarily over lives of related assets 1,508 1,574  Over-recovered wholesale transmission service expense (a) 1 year or less 52 30  Unamortized gain on reacquisition of debt Lives of related debt 27 -  Other regulatory liabilities Various 6 11  Total regulatory liabilities 2,855 2,793  Net regulatory assets (liabilities) $ (1,076) $ (1,018) ____________ (a) Not earning a return in the regulatory rate-setting process. (b) Recovery is specifically authorized by statute or by the PUCT, subject to reasonableness review. (c) Represents unfunded liabilities recorded in accordance with pension and OPEB accounting standards. (d) Includes $21 million incremental costs incurred resulting from the effects of the COVID-19 pandemic, including costs related to our pandemic response plan and $6 million related to the COVID-19 Electricity Relief Program.

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2020
Revenues [Abstract]
Disaggregation Of Revenues	  Year Ended December 31,  2020 2019  Operating revenues  Revenues contributing to earnings:  Distribution base revenues $ 2,156 $ 2,143  Transmission base revenues (TCOS revenues)  Billed to third-party wholesale customers 803 681  Billed to REPs serving Oncor distribution customers, through TCRF 446 391  Total transmission base revenues 1,249 1,072  Other miscellaneous revenues 87 77  Total revenues contributing to earnings 3,492 3,292   Revenues collected for pass-through expenses:  TCRF – third-party wholesale transmission service 975 1,005  EECRF 44 50  Revenues collected for pass-through expenses 1,019 1,055   Total operating revenues $ 4,511 $ 4,347 

Provision In Lieu Of Income T_2

Provision In Lieu Of Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Provision In Lieu Of Income Taxes [Abstract]
Schedule Of Deferred Tax Assets and Liabilities	  At December 31,  2020 2019   Deferred Tax Related Assets:  Employee benefit liabilities $ 233 $ 224  Regulatory liabilities 48 51  Other 47 28  Total 328 303  Deferred Tax Related Liabilities:  Property, plant and equipment 1,994 1,851  Regulatory assets 255 272  Other 2 1  Total 2,251 2,124  Liability in lieu of deferred income taxes – net $ 1,923 $ 1,821 
Components Of Income Tax Provisions (Benefits)	  Year Ended December 31,  2020 2019 2018   Reported in operating expenses:  Current:  U.S. federal $ 100 $ 69 $ 112  State 22 22 21  Deferred:  U.S. federal 27 49 21  State - - -  Amortization of investment tax credits (1) (2) (2)  Total reported in operating expenses 148 138 152  Reported in other income and deductions:  Current:  U.S. federal (17) (21) (32)  State - - -  Deferred federal 5 6 (3)  Total reported in other income and deductions (12) (15) (35)  Total provision in lieu of income taxes $ 136 $ 123 $ 117 
Schedule Of Income Tax Reconciliation	  Year Ended December 31,  2020 2019 2018   Income before provision in lieu of income taxes $ 849 $ 774 $ 662  Provision in lieu of income taxes at the U.S. federal statutory rate of 21% $ 178 $ 163 $ 139  Amortization of investment tax credits – net of deferred tax effect (1) (2) (2)  Amortization of excess deferred taxes (52) (52) (18)  Texas margin tax, net of federal tax benefit 18 17 17  Nontaxable gains on benefit plan investments (2) (2) (1)  Other (5) (1) (18)  Reported provision in lieu of income taxes $ 136 $ 123 $ 117  Effective rate 16.0% 15.9% 17.7% 

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2020
Short-Term Borrowings [Abstract]
Schedule Of Short-Term Borrowings	  At December 31,  2020 2019  Total credit facility borrowing capacity $ 2,000 $ 2,000  Commercial paper outstanding (a) (70) (46)  Credit facility outstanding (b) - -  Letters of credit outstanding (c) (9) (10)  Available unused credit $ 1,921 $ 1,944 ____________ (a) The weighted average interest rates for commercial paper were 0.17% and 1.84% at December 31, 2020 and December 31, 2019, respectively. (b) At December 31, 2020, the applicable interest rate for any outstanding borrowings was LIBOR plus 1.25% . (c) Interest rates on outstanding letters of credit at December 31, 2020 and December 31, 2019 were 1.45% and 1.2 0 % , respectively, based on our credit ratings.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Long-Term Debt [Abstract]
Schedule Of Long-Term Debt	  December 31,  2020 2019   Fixed Rate Secured:  5.75% Senior Notes due September 30, 2020 $ - $ 126  8.50% Senior Notes, Series C, due December 30, 2020 - 14  4.10% Senior Notes, due June 1, 2022 400 400  7.00% Debentures due September 1, 2022 482 482  2.75% Senior Notes due June 1, 2024 500 500  2.95% Senior Notes due April 1, 2025 350 350  0.55% Senior Notes due October 1, 2025 450 -  3.86% Senior Notes, Series A, due December 3, 2025 174 174  3.86% Senior Notes, Series B, due January 14, 2026 38 38  3.70% Senior Notes due November 15, 2028 650 650  5.75% Senior Notes due March 15, 2029 318 318  7.25% Senior Notes, Series B, due December 30, 2029 - 36  2.75% Senior Notes due May 15, 2030 400 -  6.47% Senior Notes, Series A, due September 30, 2030 - 83  7.00% Senior Notes due May 1, 2032 494 500  7.25% Senior Notes due January 15, 2033 323 350  7.50% Senior Notes due September 1, 2038 300 300  5.25% Senior Notes due September 30, 2040 475 475  4.55% Senior Notes due December 1, 2041 400 400  5.30% Senior Notes due June 1, 2042 348 500  3.75% Senior Notes due April 1, 2045 550 550  3.80% Senior Notes due September 30, 2047 325 325  4.10% Senior Notes due November 15, 2048 450 450  3.80% Senior Notes, due June 1, 2049 500 500  3.10% Senior Notes, due September 15, 2049 700 700  3.70% Senior Notes due May 15, 2050 400 -  5.35% Senior Notes due October 1, 2052 300 -  Secured long-term debt 9,327 8,221  Variable Rate Unsecured:  Term loan credit agreement maturing October 6, 2020 - 460  Total long-term debt 9,327 8,681  Unamortized discount and debt issuance costs (98) (56)  Less amount due currently - (608)  Long-term debt, less amounts due currently $ 9,229 $ 8,017 
Schedule Of Long-Term Debt Maturity	  Year Amount  2021 $ -  2022 882  2023 -  2024 500  2025 974  Thereafter 6,971  Unamortized discount and debt issuance costs (98)  Total $ 9,229 

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies [Abstract]
Schedule Of Lease Information	  At December 31,  2020 2019  Operating Leases:  ROU assets:  Operating lease ROU, third-party joint project and other assets $ 132 $ 92   Lease liabilities:  Operating lease and other current liabilities $ 29 $ 26  Operating lease, third-party joint project and other obligations 124 66  Total operating lease liabilities $ 153 $ 92   Weighted-average remaining lease term (in years) 7 4  Weighted-average discount rate 2.8% 3.3% 
Schedule Of Lease Costs	  Year Ended December 31,  2020 2019  Operating lease cost:  Operating lease costs (including amounts allocated to property, plant and equipment) $ 42 $ 40  Short-term lease costs 10 34  Total operating lease costs $ 52 $ 74   Operating lease payments:  Cash paid for amounts included in the measurement of lease liabilities $ 35 $ 32  
Schedule Of Operating Lease Maturity	  Year Amount  2021 $ 33  2022 30  2023 23  2024 17  2025 9  Thereafter 58  Total undiscounted lease payments 170  Less imputed interest (17)  Total operating lease obligations $ 153 

Membership Interests (Tables)

Membership Interests (Tables)	12 Months Ended
	Dec. 31, 2020
Membership Interests [Abstract]
Schedule Of Cash Capital Contributions	    Received Amount  December 23, 2020 $ 361  December 22, 2020 89  October 27, 2020 77  July 28, 2020 87  April 27, 2020 87  February 18, 2020 87  $ 788 
Schedule Of Distributions Paid	During 2020, our board of directors declared, and we paid, the following cash distributions to our members:   Declaration Date Payment Date Amount  October 28, 2020 October 29, 2020 $ 82  July 29, 2020 July 30, 2020 92  April 29, 2020 April 30, 2020 91  February 19, 2020 February 20, 2020 91  $ 356  During 2019, our board of directors declared, and we paid, the following cash distributions to our members:     Declaration Date Payment Date Amount  October 29, 2019 October 31, 2019 $ 106  July 30, 2019 July 31, 2019 71  May 1, 2019 May 2, 2019 71  February 20, 2019 February 22, 2019 71  $ 319 
Schedule Of Changes To Accumulated Other Comprehensive Income (Loss)	  Cash Flow Hedges – Interest Rate Swap Defined Benefit Pension and OPEB Plans Accumulated Other Comprehensive Income (Loss)   Balance at December 31, 2017 $ (18) $ (83) $ (101)  Defined benefit pension plans - (65) (65)  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $-) 2 - 2  Balance at December 31, 2018 $ (16) $ (148) $ (164)  Defined benefit pension plans - 27 27  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $-) 2 - 2  Amounts reclassified from accumulated other comprehensive income (loss) to capital account (4) - (4)  Balance at December 31, 2019 $ (18) $ (121) $ (139)  Defined benefit pension plans - 9 9  Cash flow hedges — net decrease in fair value of derivatives (net of tax benefit of $6) (24) - (24)  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax expense $1) 3 - 3  Balance at December 31, 2020 $ (39) $ (112) $ (151) 

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Pension And OPEB Plan Costs	  Year Ended December 31,  2020 2019 2018   Pension costs $ 71 $ 63 $ 77  OPEB costs 19 41 70  Total benefit costs 90 104 147  Less amounts recognized principally as property or a regulatory asset (13) (27) (69)  Net amounts recognized as operation and maintenance expense or other deductions $ 77 $ 77 $ 78 
Schedule Of Detailed Pension And OPEB Benefit Information	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2018 2020 2019 2018   Assumptions Used to Determine Net Periodic Pension and OPEB Costs:  Discount rate 3.13% 4.18% 3.54% 3.29% 4.41% 3.73%  Expected return on plan assets 4.94% 5.42% 5.11% 5.90% 6.19% 6.20%  Rate of compensation increase 4.64% 4.53% 4.46% - - -   Components of Net Pension and OPEB Costs:  Service cost $ 29 $ 25 $ 27 $ 6 $ 6 $ 8  Interest cost 103 128 121 32 43 44  Expected return on assets (109) (119) (120) (8) (7) (9)  Amortization of prior service cost (credit) - - - (20) (20) (30)  Amortization of net loss 48 29 49 10 19 57  Curtailment cost (credit) - - - (1) - -  Net periodic pension and OPEB costs $ 71 $ 63 $ 77 $ 19 $ 41 $ 70   Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:  Curtailment $ - $ - $ - $ 2 $ - $ -  Net loss (gain) 61 - 67 14 (22) (177)  Amortization of net loss (48) (29) (49) (10) (19) (57)  Amortization of prior service (cost) credit - - - 20 20 30  Total recognized as regulatory assets or other comprehensive income 13 (29) 18 26 (21) (204)  Total recognized in net periodic pension and OPEB costs and as regulatory assets or other comprehensive income $ 84 $ 34 $ 95 $ 45 $ 20 $ (134) 
Schedule Of Assumptions Used	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2018 2020 2019 2018   Assumptions Used to Determine Benefit Obligations at Period End:  Discount rate 2.40% 3.13% 4.18% 2.58% 3.29% 4.41%  Rate of compensation increase 4.80% 4.64% 4.53% - - - 
Schedule Of Changes In Projected Benefit Obligations And Changes In Fair Value Of Plan Assets And Net Funded Status	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2020 2019   Change in Projected Benefit Obligation:  Projected benefit obligation at beginning of year $ 3,400 $ 3,162 $ 999 $ 1,006  Service cost 29 25 6 6  Interest cost 103 128 32 43  Participant contributions - - 18 19  Actuarial loss (gain) 302 367 20 (5)  Benefits paid (165) (164) (63) (70)  Curtailment - - 1 -  Settlements (73) (118) - -  Projected benefit obligation at end of year $ 3,596 $ 3,400 $ 1,013 $ 999  Accumulated benefit obligation at end of year $ 3,433 $ 3,283 $ - $ -   Change in Plan Assets:  Fair value of assets at beginning of year $ 2,494 $ 2,249 $ 141 $ 132  Actual return on assets 350 486 14 25  Employer contributions 134 41 35 35  Participant contributions - - 18 19  Benefits paid (165) (164) (63) (70)  Settlements (73) (118) - -  Fair value of assets at end of year $ 2,740 $ 2,494 $ 145 $ 141   Funded Status:  Projected benefit obligation at end of year $ (3,596) $ (3,400) $ (1,013) $ (999)  Fair value of assets at end of year 2,740 2,494 145 141  Funded status at end of year $ (856) $ (906) $ (868) $ (858) 
Schedule Of Amounts Recognized In Balance Sheet	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2020 2019 2020 2019   Amounts Recognized in the Balance Sheet Consist of:  Liabilities:  Other current liabilities $ (5) $ (5) $ (14) $ (15)  Other noncurrent liabilities (863) (901) (854) (843)  Net liability recognized $ (868) $ (906) $ (868) $ (858)  Assets:  Other noncurrent assets $ 12 $ - $ - $ -  Regulatory assets:  Net loss 556 531 132 129  Prior service credit - - (16) (37)  Net regulatory assets recognized 556 531 116 92  Net assets recognized $ 568 $ 531 $ 116 $ 92  Accumulated other comprehensive net loss $ 108 $ 120 $ 3 $ 1 
Schedule Of Projected Benefit Obligations And Accumulated Benefit Obligations In Excess Of Plan Assets Fair Value	The following table provides information regarding pension plans with projected benefit obligations (PBO) and accumulated benefit obligations (ABO) in excess of the fair value of plan assets.     At December 31,  2020 2019  Pension Plans with PBO and ABO in Excess of Plan Assets (a):  Projected benefit obligations $ 3,596 $ 3,400  Accumulated benefit obligations 3,433 3,283  Plan assets 2,740 2,494 _________ (a) PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan are included . Oncor ’s obligations with respect to the Vistra Retirement Plan are overfunded. As of December 31, 2020, PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan were $196 million , $194 million and $208 million , respectively. As of December 31, 2019, PBO, ABO and the plan assets relating to Oncor ’s obligations with respect to the Vistra Retirement Plan were $187 million , $184 million and $197 million , respectively.  The following table provides information regarding OPEB plans with accumulated projected benefit obligations (APBO) in excess of the fair value of plan assets.    At December 31,  2020 2019  OPEB Plans with APBO in Excess of Plan Assets  Accumulated postretirement benefit obligations $ 1,013 $ 999  Plan assets 145 141 
Schedule Of Target Asset Allocation Ranges By Asset Category	  Target Allocation Ranges  Asset Category Recoverable Non-recoverable   International equities 13% - 21% 6% - 12%  U.S. equities 16% - 24% 8% - 14%  Real estate 3% - 7% -  Credit strategies 5% - 10% 5% - 9%  Fixed income 45% - 55% 68% - 78% 
Schedule Of Expected Long-Term Rate Of Return On Assets Assumptions	    Pension Plans Oncor OPEB Plans  Asset Class Expected Long-Term Rate of Return Asset Class Expected Long-Term Rate of Return   International equity securities 7.58% 401(h) accounts 5.59%  U.S. equity securities 6.50% Life insurance VEBA 5.10%  Real estate 5.60% Union VEBA 5.10%  Credit strategies 3.90% Non-union VEBA 1.10%  Fixed income securities 2.32% Shared retiree VEBA 1.10%  Weighted average (a) 4.57% Weighted average 5.24% _____________ (a) The 2021 expected long-term rate of return for the nonregulated portion of the Oncor Retirement Plan is 3.75% , an d for Oncor’s obligations with respect to the Vistra Retirement Plan is 4.20% . 
Schedule Of Contributions	  Year Ended December 31,  2020 2019 2018   Pension plans contributions $ 134 $ 41 $ 82  Oncor OPEB Plans contributions 35 35 41  Total contributions $ 169 $ 76 $ 123 
Schedule Of Estimated Future Benefit Payments	  2021 2022 2023 2024 2025 2026-30   Pension plans $ 186 $ 189 $ 192 $ 195 $ 197 $ 975  Oncor OPEB Plans $ 49 $ 51 $ 52 $ 53 $ 54 $ 271 
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Assets Fair Value Measured On Recurring Basis	  At December 31, 2020  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 220 $ 1 $ - $ 221  International 330 1 - 331  Fixed income securities:  Corporate bonds (a) - 910 - 910  U.S. Treasuries - 46 - 46  Other (b) - 57 - 57  Total assets in the fair value hierarchy $ 550 $ 1,015 $ - 1,565  Total assets measured at net asset value (c) 1,175  Total fair value of plan assets $ 2,740   At December 31, 2019  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 194 $ 2 $ - $ 196  International 290 1 - 291  Fixed income securities:  Corporate bonds (a) - 908 - 908  U.S. Treasuries - 147 - 147  Other (b) - 63 - 63  Real estate - - 3 3  Total assets in the fair value hierarchy $ 484 $ 1,121 $ 3 1,608  Total assets measured at net asset value (c) 886  Total fair value of plan assets $ 2,494 _____________ (a) Substantially all corporate bonds are rated investment grade by Fitch, Moody’s or S&P. (b) Other consists primarily of municipal bonds, emerging market debt, bank loans and fixed income derivative instruments. (c) Fair value was measured using the net asset value (NAV) per share as a practical expedient as the investments did not have a readily determinable fair value and are not required to be classified in the fair value hierarchy. The NAV fair value amounts presented here are intended to permit a reconciliation to the total fair value of plan assets.
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Assets Fair Value Measured On Recurring Basis	  At December 31, 2020  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 9 $ - $ - $ 9  Equity securities:  U.S. 24 - - 24  International 25 - - 25  Fixed income securities:  Corporate bonds (a) - 34 - 34  U.S. Treasuries - 1 - 1  Other (b) 19 3 - 22  Total assets in the fair value hierarchy $ 77 $ 38 $ - 115  Total assets measured at net asset value (c) 30  Total fair value of plan assets $ 145   At December 31, 2019  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 6 $ - $ - $ 6  Equity securities:  U.S. 24 - - 24  International 28 - - 28  Fixed income securities:  Corporate bonds (a) - 31 - 31  U.S. Treasuries - 3 - 3  Other (b) 22 2 - 24  Total assets in the fair value hierarchy $ 80 $ 36 $ - 116  Total assets measured at net asset value (c) 25  Total fair value of plan assets $ 141 _____________ (a) Substantially all corporate bonds are rated investment grade by Fitch, Moody’s or S&P. (b) Other consists primarily of diversified bond mutual funds. (c) Fair value was measured using the net asset value (NAV) per share as a practical expedient as the investments did not have a readily determinable fair value and are not required to be classified in the fair value hierarchy. The NAV fair value amounts presented here are intended to permit a reconciliation to the total fair value of plan assets.
Postretirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Assumptions Used	  Year Ended December 31,  2020 2019   Assumed Health Care Cost Trend Rates – Not Medicare Eligible:  Health care cost trend rate assumed for next year 6.90% 7.20%  Rate to which the cost trend is expected to decline (the ultimate trend rate) 4.50% 4.50%  Year that the rate reaches the ultimate trend rate 2029 2029   Assumed Health Care Cost Trend Rates – Medicare Eligible:  Health care cost trend rate assumed for next year 7.80% 8.00%  Rate to which the cost trend is expected to decline (the ultimate trend rate) 4.50% 4.50%  Year that the rate reaches the ultimate trend rate 2030 2029 

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Related-Party Transactions [Abstract]
Schedule Of Cash Payments Made To (Received From) Related Parties	Amounts payable to (receivable from) members related to income taxes under the agreement and reported on our balance sheet consisted of the following:    At December 31, 2020 At December 31, 2019  STH Texas Transmission Total STH Texas Transmission Total   Federal income taxes payable (receivable) $ (6) $ (1) $ (7) $ (2) $ (1) $ (3)  Texas margin tax payable 23 - 23 22 - 22  Net payable (receivable) $ 17 $ (1) $ 16 $ 20 $ (1) $ 19  Cash payments made to (received from) members related to income taxes consisted of the following:    Year Ended December 31,  2020 2019 2018  STH Texas Transm. Total STH Texas Transm. Total STH EFH Corp. Texas Transm. Total   Federal income taxes $ 70 $ 17 $ 87 $ 45 $ 11 $ 56 $ 59 $ (19) $ 10 $ 50  Texas margin taxes 22 - 22 22 - 22 21 - - 21  Total payments (receipts) $ 92 $ 17 $ 109 $ 67 $ 11 $ 78 $ 80 $ (19) $ 10 $ 71 

Supplementary Financial Infor_2

Supplementary Financial Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplementary Financial Information [Abstract]
Schedule Of Other Deductions And (Income)	     Year Ended December 31,  2020 2019 2018   Professional fees $ 6 $ 10 $ 12  Sempra Acquisition related costs - - 12  InfraREIT Acquisition related costs - 9 -  Recoverable Pension and OPEB - non-service costs 55 57 53  Non-recoverable pension and OPEB 4 4 6  AFUDC equity income (29) (10) -  Interest income (4) (5) (1)  Other 1 (2) 2  Total other deductions and (income) - net $ 33 $ 63 $ 84 
Schedule Of Interest Expense And Related Charges	  Year Ended December 31,  2020 2019 2018   Interest $ 413 $ 382 $ 358  Amortization of debt issuance costs and discounts 11 9 6  Less AFUDC – capitalized interest portion (19) (16) (13)  Total interest expense and related charges $ 405 $ 375 $ 351 
Schedule Of Trade Accounts And Other Receivables	  At December 31,  2020 2019   Gross trade accounts and other receivables $ 767 $ 666  Allowance for uncollectible accounts (7) (5)  Trade accounts receivable – net $ 760 $ 661 
Summary of Investments And Other Property	  At December 31,  2020 2019   Assets related to employee benefit plans $ 124 $ 119  Land 16 12  Other 2 2  Total investments and other property $ 142 $ 133 
Schedule Of Property, Plant And Equipment	  Composite Depreciation Rate/ At December 31,  Avg. Life at December 31, 2020 2020 2019  Assets in service:  Distribution 2.5% / 39.4 years $ 14,937 $ 14,007  Transmission 2.9% / 34.8 years 12,156 11,094  Other assets 6.7% / 14.9 years 1,855 1,648  Total 28,948 26,749  Less accumulated depreciation 8,336 7,986  Net of accumulated depreciation 20,612 18,763  Construction work in progress 593 585  Held for future use 20 22  Property, plant and equipment – net $ 21,225 $ 19,370 
Schedule Of Intangible Assets	  At December 31, 2020 At December 31, 2019  Gross Gross  Carrying Accumulated Carrying Accumulated  Amount Amortization Net Amount Amortization Net  Identifiable intangible assets subject to amortization:  Land easements $ 623 $ 112 $ 511 $ 575 $ 107 $ 468  Capitalized software 1,027 484 543 933 430 503  Total $ 1,650 $ 596 $ 1,054 $ 1,508 $ 537 $ 971 
Schedule Of Estimated Aggregate Amortization Expenses	  Year Amortization Expense   2021 $ 68  2022 68  2023 68  2024 67  2025 67 
Schedule Of Operating Lease, Third Party Joint Project And Other Obligations	  At December 31,  2020 2019   Operating lease liabilities (Notes 1 and 7) $ 124 $ 66  Investment tax credits 5 6  Third-party joint project obligation (Note 1) (a) 100 4  Other 76 70  Total operating lease, third-party joint project and other obligations $ 305 $ 146 ____________ (a) Oncor is currently involved in a joint project with LP&L. See Note 3 for more information. 
Schedule Of Supplemental Cash Flow Information	  Year Ended December 31,  2020 2019 2018  Cash payments (receipts) related to:   Interest $ 406 $ 368 $ 368  Less capitalized interest (19) (16) (13)  Interest payments (net of amounts capitalized) $ 387 $ 352 $ 355   Amount in lieu of income taxes (a):  Federal $ 87 $ 56 $ 50  State 22 22 21  Total payments (receipts) in lieu of income taxes $ 109 $ 78 $ 71   Noncash increase in operating lease obligation for ROU assets $ 72 $ 38 $ -   Noncash investing and financing activity:   Acquisition (b):  Assets acquired $ - $ 2,547 $ -  Liabilities assumed - (1,223) -  Cash paid $ - $ 1,324 $ -   Debt exchange (c):  Debt issued in debt exchange offering $ 300 $ - $ -  Debt exchanged in debt exchange offering (300) - -  $ - $ - $ -   Noncash construction expenditures (d) $ 254 $ 278 $ 174 ______________ (a) See Note 11 for income tax related detail. (b) See Note 13 for more information on noncash debt exchanges related to InfraREIT Acquisition. (c) See Note 6 for more information on noncash debt exchanges related to 2052 Notes issuance. (d) Represents end-of-period accruals.
Schedule Of Quarterly Information	  2020 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 1,072 $ 1,090 $ 1,232 $ 1,117  Operating income 242 285 362 250  Net income 131 176 258 148   2019 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 1,016 $ 1,041 $ 1,211 $ 1,079  Operating income 216 253 369 236  Net income 116 139 263 133 

Acquisition Activity (Tables)

Acquisition Activity (Tables)	12 Months Ended
	Dec. 31, 2020
Acquisition Activity [Abstract]
Total Purchase Price Paid	  Purchase of outstanding InfraREIT shares and units $ 1,275  Certain transaction costs of InfraREIT paid by Oncor through June 30, 2019 (a) 53  Total purchase price paid through June 30, 2019 1,328  Adjustments made in the period from June 30, 2019 through March 31, 2020 (4)  Total purchase price paid $ 1,324 ________________ Represents certain transaction costs incurred by InfraREIT in connection with the transaction and paid by Oncor, including a $40 million management termination fee payable to an affiliate of Hunt Consolidated, Inc.
Assets And Liabilities Assumed	  Purchase price allocation is as follows:  As of May 16, 2019  Assets acquired:  Current assets $ 45  Property, plant and equipment - net 1,800  Goodwill 676  Regulatory assets 16  Other noncurrent assets 10  Total assets acquired 2,547   Liabilities assumed:  Short-term debt 115  Other current liabilities 24  Regulatory liabilities 148  Liability in lieu of deferred income taxes 97  Long-term debt, including due currently 839  Total liabilities assumed 1,223  Net assets acquired 1,324  Total purchase price paid $ 1,324 
Pro Forma Information	  Year Ended December 31,  2019 2018  Oncor Consolidated Pro Forma Revenues $ 4,431 $ 4,318 

Description Of Business And S_3

Description Of Business And Significant Accounting Policies (Narrative) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)entity	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business And Significant Accounting Polices [Line Items]
Ownership holding period									5 years
Number of disinterested directors | entity									7
Direct or indirect ownership interest time period									10 years
Disinterested directors expenditure budget percentage									10.00%
Goodwill impairment | $									$ 0	$ 0	$ 0
Goodwill | $	$ 4,740,000,000				$ 4,740,000,000				4,740,000,000	4,740,000,000
Revenues | $	1,117,000,000	$ 1,232,000,000	$ 1,090,000,000	$ 1,072,000,000	1,079,000,000	$ 1,211,000,000	$ 1,041,000,000	$ 1,016,000,000
InfraREIT [Member]
Business And Significant Accounting Polices [Line Items]
Goodwill | $	$ 676,000,000				$ 676,000,000				$ 676,000,000	$ 676,000,000
Oncor Holdings [Member]
Business And Significant Accounting Polices [Line Items]
Number of disinterested directors | entity									2
Texas Transmission [Member]
Business And Significant Accounting Polices [Line Items]
Number of disinterested directors | entity									2
Sempra Energy [Member]
Business And Significant Accounting Polices [Line Items]
Number of disinterested directors | entity									2
Oncor Holdings [Member]
Business And Significant Accounting Polices [Line Items]
Ownership	80.25%								80.25%
Oncor Holdings [Member] | Sempra Energy [Member]
Business And Significant Accounting Polices [Line Items]
Ownership interests acquired	51.00%								51.00%
Texas Transmission [Member]
Business And Significant Accounting Polices [Line Items]
Percentage of membership interest owned by non-controlling owners	19.75%								19.75%

Description Of Business And S_4

Description Of Business And Significant Accounting Policies (Schedule Of Adoption Of Topic 842) (Details) $ in Millions	Dec. 31, 2019USD ($)
Description Of Business And Significant Accounting Policies [Abstract]
Operating lease ROU assets and other	$ 92

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	Jul. 09, 2019USD ($)	Apr. 30, 2020USD ($)	Sep. 30, 2018USD ($)	May 31, 2019USD ($)	Nov. 26, 2017USD ($)	Dec. 31, 2020USD ($)$ / MWh	Dec. 31, 2019USD ($)
Regulatory Matters [Abstract]
Reconciliation of all costs incurred with revenues					$ 87
Net operating cost savings	$ 16
Authorized under-recovery reconciliation costs	$ 6
Expected surcharge		$ 7
Decrease in revenue requirement			$ 144
Reduction related to amortization of excess deferred income taxes			$ 75
Refund of tax rate differential				$ 9
Per MWh surcharge to be collected | $ / MWh						0.33
Net regulatory asset						$ (1,076)	$ (1,018)

Regulatory Matters (Components

Regulatory Matters (Components Of Regulatory Assets And Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets And Liabilities [Line Items]
Carrying Amount, Regulatory Assets	$ 1,779	$ 1,775
Carrying Amount, Regulatory Liabilities	2,855	2,793
Net regulatory assets (liabilities)	$ (1,076)	(1,018)
Estimated Net Removal Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Lives of related assets
Carrying Amount, Regulatory Liabilities	$ 1,262	1,178
Excess Deferred Taxes [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Primarily over lives of related assets
Carrying Amount, Regulatory Liabilities	$ 1,508	1,574
Over-Recovered Wholesale Transmission Service Expense [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	1 year or less
Carrying Amount, Regulatory Liabilities	$ 52	30
Other Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Various
Carrying Amount, Regulatory Liabilities	$ 6	11
Employee Retirement Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 672	623
Employee Retirement Costs Being Amortized [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	7 years
Carrying Amount, Regulatory Assets	$ 227	262
Employee Retirement Costs Incurred Since The Last Rate Review Period [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 67	79
Self-Insurance Reserve (Primarily Storm Recovery Costs) Being Amortized [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	7 years
Carrying Amount, Regulatory Assets	$ 266	309
Self-Insurance Reserve Incurred Since The Last Rate Review Period (Primarily Storm Related) [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 256	238
Debt Reacquisition Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Lives of related debt
Carrying Amount, Regulatory Assets	$ 25	29
Under-recovered AMS Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	7 years
Carrying Amount, Regulatory Assets	$ 149	170
Energy Efficiency Performance Bonus [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	1 year or less
Carrying Amount, Regulatory Assets	$ 14	9
Wholesale Distribution Substation Service [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 55	34
Unrecovered Expenses Related To COVID-19 [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 27
Costs related to pandemic response plan	21
Costs related to electricity relief program	$ 6
Other Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Various
Carrying Amount, Regulatory Assets	$ 21	$ 22

Revenues (Narrative) (Details)

Revenues (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)customeritem	Dec. 31, 2019USD ($)	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Approved bonus | $	$ 14	$ 9
Number of REPS | customer	95
Number of counterparties | item	2
REP Subsidiary One [Member] | Revenue Benchmark [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	25.00%	23.00%	23.00%
REP Subsidiary Two [Member] | Revenue Benchmark [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	18.00%	18.00%	19.00%

Revenues (Disaggregation Of Rev

Revenues (Disaggregation Of Revenues) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	$ 3,492	$ 3,292
Revenues collected for pass-through expenses	1,019	1,055
Total operating revenues	4,511	4,347	$ 4,101
Distribution Base Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	2,156	2,143
Transmission Base Revenues (TCOS Revenues) [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	1,249	1,072
Transmission Base Revenues (TCOS Revenues) [Member] | Third-Party Wholesale Customers [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	803	681
Transmission Base Revenues (TCOS Revenues) [Member] | REPS Serving Oncor Distribution Customers, Through TCRF [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	446	391
Other Miscellaneous Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	87	77
TCRF - Third-party Wholesale Transmission Service [Member]
Disaggregation of Revenue [Line Items]
Revenues collected for pass-through expenses	975	1,005
EECRF [Member]
Disaggregation of Revenue [Line Items]
Revenues collected for pass-through expenses	$ 44	$ 50

Provision In Lieu Of Income T_3

Provision In Lieu Of Income Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provision In Lieu Of Income Taxes [Abstract]
Net liability in lieu of deferred income taxes	$ 1,923,000,000	$ 1,821,000,000
Accrued interest	0	0
Benefit (expense) from interest and penalties	$ 0	$ 0	$ 0

Provision In Liew Of Income Tax

Provision In Liew Of Income Taxes (Schedule Of Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Provision In Lieu Of Income Taxes [Abstract]
Deferred tax assets, Employee benefit liabilities	$ 233	$ 224
Deferred tax assets, Regulatory liabilities	48	51
Deferred tax assets, Other	47	28
Total	328	303
Deferred tax liabilities, Property, plant and equipment	1,994	1,851
Deferred tax liabilities, Regulatory assets	255	272
Deferred Tax Liabilities, Other	2	1
Total	2,251	2,124
Liability in lieu of deferred income taxes - net	$ 1,923	$ 1,821

Provision In Lieu Of Income T_4

Provision In Lieu Of Income Taxes (Components Of Income Tax Provisions (Benefits)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provision In Lieu Of Income Taxes [Abstract]
Current: U.S. federal	$ 100	$ 69	$ 112
Current: State	22	22	21
Deferred: U.S. federal	27	49	21
Amortization of investment tax credits	(1)	(2)	(2)
Total reported in operating expenses	148	138	152
U.S. federal	(17)	(21)	(32)
Deferred federal	5	6	(3)
Total reported in other income and deductions	(12)	(15)	(35)
Total provision in lieu of income taxes	$ 136	$ 123	$ 117

Provision In Lieu Of Income T_5

Provision In Lieu Of Income Taxes (Schedule Of Income Tax Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provision In Lieu Of Income Taxes [Abstract]
Income before provision in lieu of income taxes	$ 849	$ 774	$ 662
Provision in lieu of income taxes at the U.S. federal statutory rate of 21% for 2019 and 2018 and 35% for 2017	178	163	139
Amortization of investment tax credits - net of deferred tax effect	(1)	(2)	(2)
Amortization of excess deferred taxes	(52)	(52)	(18)
Texas margin tax, net of federal tax benefit	18	17	17
Nontaxable gains on benefit plan investments	(2)	(2)	(1)
Other	(5)	(1)	(18)
Total provision in lieu of income taxes	$ 136	$ 123	$ 117
Effective rate	16.00%	15.90%	17.70%

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Nov. 30, 2017
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Outstanding borrowing, interest rate	1.45%
Commitment fee	0.10%
Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 2,000
Extension period for revolving line of credit	1 year
Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Possible additional increase in borrowing capacity amount		100
Libor rate depending on credit ratings	0.75%
Commitment fee	0.225%
Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Possible additional increase in borrowing capacity amount		$ 400
Libor rate depending on credit ratings	0.125%
Commitment fee	0.075%
London Interbank Offered Rate (LIBOR) [Member] | Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Libor rate depending on credit ratings	1.75%
London Interbank Offered Rate (LIBOR) [Member] | Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Libor rate depending on credit ratings	1.125%

Short-Term Borrowings (Schedule

Short-Term Borrowings (Schedule Of Short-Term Borrowings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Total credit facility borrowing capacity	$ 2,000	$ 2,000
Commercial Paper [Member]
Short-term Debt [Line Items]
Outstanding	$ (70)	$ (46)
Weighted average interest rate	0.17%	1.84%
Letter of Credit [Member]
Short-term Debt [Line Items]
Outstanding	$ (9)	$ (10)
Weighted average interest rate	1.45%	1.20%
London Interbank Offered Rate (LIBOR) [Member]
Short-term Debt [Line Items]
Spread over variable rate	1.25%
London Interbank Offered Rate (LIBOR) [Member] | Credit Facility [Member]
Short-term Debt [Line Items]
Spread over variable rate	1.00%
Federal Funds Effective Rate [Member] | Credit Facility [Member]
Short-term Debt [Line Items]
Spread over variable rate	0.50%

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($)	Sep. 28, 2020	Sep. 23, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Long-Term Debt [Line Items]
Repayments of long-term debt				$ 1,164,000,000	$ 1,094,000,000	$ 825,000,000
Percentage of fair value of cost of property additions certified to the Deed of Trust collateral agent				85.00%
Available bond credits				$ 2,115,000,000
Future debt subject to property additions to the Deed of Trust				3,328,000,000
Estimated fair value of our long-term debt including current maturities				$ 11,638,000,000	10,003,000,000
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt [Line Items]
Spread over variable rate				1.25%
0.55% Senior Notes due October 1, 2025 [Member]
Long-Term Debt [Line Items]
Proceeds from sale of Notes	$ 443,000,000
Redemption percentage	100.00%
2030 And 2050 Notes [Member]
Long-Term Debt [Line Items]
Proceeds from sale of Notes			$ 790,000,000
Term Loan Agreement Maturing June 1, 2021 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				$ 450,000,000
Term Loan Agreement Maturing June 1, 2021 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt [Line Items]
Spread over variable rate				0.50%
March 2020 Term Loan Agreement [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				$ 350,000,000
Term loan				$ 110,000,000
March 2020 Term Loan Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt [Line Items]
Spread over variable rate				0.95%
7.25% Senior Notes, Series B, due December 30, 2029 [Member]
Long-Term Debt [Line Items]
Debt exchange, amount		$ 35,000,000
6.47% Senior Notes, Series A, due September 30, 2030 [Member]
Long-Term Debt [Line Items]
Debt exchange, amount		80,000,000
7.00% Fixed Senior Notes Due May 1, 2032 [Member]
Long-Term Debt [Line Items]
Debt exchange, amount		6,000,000
7.25% Fixed Senior Notes Due January 15, 2033 [Member]
Long-Term Debt [Line Items]
Debt exchange, amount		27,000,000
Debt Exchange And 2052 Notes Issuance [Member]
Long-Term Debt [Line Items]
Proceeds from sale of Notes		$ 0
Redemption percentage				100.00%
Increase in basis points per annum				0.50%
Secured Debt [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				$ 9,327,000,000	8,221,000,000
Secured Debt [Member] | 0.55% Senior Notes due October 1, 2025 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				450,000,000
Secured Debt [Member] | 2.75% Senior Notes due May 15, 2030 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				400,000,000
Secured Debt [Member] | 3.70% Senior Notes Due May 15, 2050 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				400,000,000
Secured Debt [Member] | 5.75% Fixed Senior Notes Due September 30, 2020 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount					126,000,000
Secured Debt [Member] | 7.25% Senior Notes, Series B, due December 30, 2029 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount					36,000,000
Secured Debt [Member] | 6.47% Senior Notes, Series A, due September 30, 2030 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount					83,000,000
Secured Debt [Member] | 7.00% Fixed Senior Notes Due May 1, 2032 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				494,000,000	500,000,000
Secured Debt [Member] | 7.25% Fixed Senior Notes Due January 15, 2033 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				323,000,000	350,000,000
Secured Debt [Member] | 5.30% Fixed Senior Notes Due June 1, 2042 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				348,000,000	500,000,000
Secured Debt [Member] | 5.35% Senior Notes due October 1, 2052 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount				$ 300,000,000
Unsecured Debt [Member] | Term Loan Credit Agreement Maturing December 9, 2019 [Member]
Long-Term Debt [Line Items]
Term loan					$ 460,000,000

Long-Term Debt (Schedule Of Lon

Long-Term Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	$ (98)	$ (56)
Less amount due currently		(608)
Long-term debt, less amounts due currently	9,229	8,017
Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	9,327	8,221
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 9,327	8,681
5.75% Fixed Senior Notes Due September 30, 2020 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt		$ 126
Interest percentage	5.75%	5.75%
8.50% Senior Notes, Series C, due December 30, 2020 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt		$ 14
Interest percentage	8.50%	8.50%
4.10% Fixed Senior Notes Due June 1, 2022 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400	$ 400
Interest percentage	4.10%	4.10%
7.00% Fixed Debentures Due September 1, 2022 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 482	$ 482
Interest percentage	7.00%
2.75% Senior Notes due June 1, 2024 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500	500
Interest percentage	2.75%
2.95% Fixed Senior Notes Due April 1, 2025 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 350	$ 350
Interest percentage	2.95%
0.55% Senior Notes due October 1, 2025 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 450
Interest percentage	0.55%	0.55%
3.86% Senior Notes, Series A, due December 3, 2025 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 174	$ 174
Interest percentage	3.86%	3.86%
3.86% Senior Notes, Series B, due January 14, 2026 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 38	$ 38
Interest percentage	3.86%	3.86%
3.70% Fixed Senior Notes Due November 15, 2028 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 650	$ 650
Interest percentage	3.70%	3.70%
5.75% Fixed Senior Notes Due March 15, 2029 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 318	$ 318
Interest percentage	5.75%	5.75%
7.25% Senior Notes, Series B, due December 30, 2029 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt		$ 36
Interest percentage	7.25%	7.25%
2.75% Senior Notes due May 15, 2030 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400
Interest percentage	2.75%
6.47% Senior Notes, Series A, due September 30, 2030 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt		$ 83
Interest percentage	6.47%	6.47%
7.00% Fixed Senior Notes Due May 1, 2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 494	$ 500
Interest percentage	7.00%	7.00%
7.25% Fixed Senior Notes Due January 15, 2033 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 323	$ 350
Interest percentage	7.25%	7.25%
7.50% Fixed Senior Notes Due September 1, 2038 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 300	$ 300
Interest percentage	7.50%	7.50%
5.25% Fixed Senior Notes Due September 30, 2040 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 475	$ 475
Interest percentage	5.25%	5.25%
4.55% Fixed Senior Notes Due December 1, 2041 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400	$ 400
Interest percentage	4.55%	4.55%
5.30% Fixed Senior Notes Due June 1, 2042 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 348	$ 500
Interest percentage	5.30%	5.30%
3.75% Fixed Senior Notes Due April 1, 2045 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 550	$ 550
Interest percentage	3.75%	3.75%
3.80% Fixed Senior Notes Due September 30, 2047 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 325	$ 325
Interest percentage	3.80%	3.80%
4.10% Fixed Senior Notes Due November 15, 2048 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 450	$ 450
Interest percentage	4.10%	4.10%
3.80% Senior Notes, Due June 1, 2049 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500	$ 500
Interest percentage	3.80%	3.80%
3.10% Senior Notes, Due September 15, 2049 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 700	$ 700
Interest percentage	3.10%	3.10%
3.70% Senior Notes Due May 15, 2050 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400
Interest percentage	3.70%	3.70%
5.35% Senior Notes due October 1, 2052 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 300
Interest percentage	5.35%	5.35%
Term Loan Credit Agreement Maturing December 9, 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Term loan		$ 460
Term Loan Agreement Maturing June 1, 2021 [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 450

Long-Term Debt (Schedule Of L_2

Long-Term Debt (Schedule Of Long-Term Debt Maturity) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Long-Term Debt [Abstract]
2022	$ 882
2024	500
2024	974
Thereafter	6,971
Unamortized discount and debt issuance costs	(98)	$ (56)
Total	$ 9,229

Commitments And Contingencies_2

Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Commitments And Contingencies [Abstract]
Lease term	20 years
Business Combination, Minimum Capital Expenditures Over Five Year Period	$ 7,500
2020 required efficiency spending amount	$ 52
Percentage of full time employees represented by labor union	17.00%
Expiration date of collective bargaining agreement	Oct. 1, 2022

Commitments And Contingencies_3

Commitments And Contingencies (Schedule Of Lease Information) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating lease ROU and other assets		$ 92
Weighted-average remaining lease term (in years)		4 years
Weighted-average discount rate		3.30%
Other Current Liabilities [Member]
Operating and other current liabilities		$ 26
Other Noncurrent Liabilities [Member]
Employee benefit, operating lease and other obligations		66
Other Liabilities [Member]
Total operating lease liabilities	$ 153	$ 92

Commitments And Contingencies_4

Commitments And Contingencies (Schedule Of Lease Costs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Commitments And Contingencies [Abstract]
Operating lease costs (including amounts allocated to property, plant and equipment)	$ 40
Short-term lease costs	34
Total operating lease costs	74
Cash paid for amounts included in the measurement of lease liabilities	$ 32

Commitments And Contingencies_5

Commitments And Contingencies (Schedule Of Operating Lease Maturity) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
2021	$ 33
2022	30
2023	23
2024	17
2024	9
Thereafter	58
Total undiscounted lease payments	170
Less imputed interest	(17)
Other Liabilities [Member]
Total future minimum lease payments	$ 153	$ 92

Membership Interests (Narrative

Membership Interests (Narrative) (Details) - USD ($) $ in Millions	Feb. 16, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 19, 2021
Subsequent Event [Line Items]
Regulatory liability balance		$ 1,426
Members contribution		$ 788	$ 1,978	$ 284
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash available for distribution					$ 96
Members contribution	$ 63

Membership Interests (Schedule

Membership Interests (Schedule Of Cash Capital Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Members contribution	$ 788	$ 1,978	$ 284
December 23, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	361
December 22, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	89
October 27, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	77
July 28, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	87
April 27, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	87
February 18, 2020 [Member]
Related Party Transaction [Line Items]
Members contribution	$ 87

Membership Interests (Schedul_2

Membership Interests (Schedule Of Distributions Paid) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Dividends Payable [Line Items]
Amount	$ 356	$ 319	$ 209
Payment One FY 2020 [Member]
Dividends Payable [Line Items]
Declaration Date	Oct. 28, 2020
Payment Date	Oct. 29, 2020
Amount	$ 82
Payment Two FY 2020 [Member]
Dividends Payable [Line Items]
Declaration Date	Jul. 29, 2020
Payment Date	Jul. 30, 2020
Amount	$ 92
Payment Three FY 2020 [Member]
Dividends Payable [Line Items]
Declaration Date	Apr. 29, 2020
Payment Date	Apr. 30, 2020
Amount	$ 91
Payment Four FY 2020 [Member]
Dividends Payable [Line Items]
Declaration Date	Feb. 19, 2020
Payment Date	Feb. 20, 2020
Amount	$ 91
Payment One FY 2019 [Member]
Dividends Payable [Line Items]
Declaration Date		Oct. 29, 2019
Payment Date		Oct. 31, 2019
Amount		$ 106
Payment Two FY 2019 [Member]
Dividends Payable [Line Items]
Declaration Date		Jul. 30, 2019
Payment Date		Jul. 31, 2019
Amount		$ 71
Payment Three FY 2019 [Member]
Dividends Payable [Line Items]
Declaration Date		May 1, 2019
Payment Date		May 2, 2019
Amount		$ 71
Payment Four FY 2019 [Member]
Dividends Payable [Line Items]
Declaration Date		Feb. 20, 2019
Payment Date		Feb. 22, 2019
Amount		$ 71

Membership Interests (Schedul_3

Membership Interests (Schedule Of Changes To Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (139)
Balance at end of period	(151)	$ (139)
Cash Flow Hedges - Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(16)	(18)
Defined benefit pension plans
Cash flow hedges — net decrease in fair value of derivatives (net of tax benefit of $6)	2	2
Amounts reclassified from AOCI to capital account	(4)
Balance at end of period	(18)	(16)
Defined Benefit Pension and OPEB Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(148)	(83)
Defined benefit pension plans	27	(65)
Cash flow hedges — net decrease in fair value of derivatives (net of tax benefit of $6)
Amounts reclassified from AOCI to capital account
Balance at end of period	(121)	(148)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(164)	(101)
Defined benefit pension plans	27	(65)
Cash flow hedges — net decrease in fair value of derivatives (net of tax benefit of $6)	2	2
Amounts reclassified from AOCI to capital account	(4)
Balance at end of period	$ (139)	$ (164)

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets		$ 1,779	$ 1,775
Number of OPEB plans | item		2
Rolling period		4 years
Percentage of gains and losses		25.00%
Second pool representation of total investments, percentage		25.00%
Cash contributions		$ 169	76	$ 123
Thrift Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions		$ 23	20	19
Oncor Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of corporate bonds | item		862
Pension And OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets		$ 966,000	964,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain		(302)	(367)
Net gain (loss)		(61)		(67)
Unfunded liability		(856)	(906)
Amortization of net loss		48	29	49
Amortization of net actuarial loss		(48)	$ (29)	$ (49)
Expected funding, 2019		24
Expected funding, 2019 to 2023		$ 560
Discount rate		3.13%	4.18%	3.54%
Expected return on plan assets		4.94%	5.42%	5.11%
Cash contributions		$ 134	$ 41	$ 82
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain		(20)	5
Net gain (loss)		(14)	22	177
Unfunded liability		$ (868)	(858)
Number of corporate bonds | item		305
Amortization of net loss		$ 10	19	57
Amortization of prior service cost (credit)		(20)	(20)	(30)
Amortization of net actuarial loss		(10)	$ (19)	$ (57)
Expected funding, 2019		35
Expected funding, 2019 to 2023		$ 176
Discount rate		3.29%	4.41%	3.73%
Expected return on plan assets		5.90%	6.19%	6.20%
Cash contributions		$ 35	$ 35	$ 41
OPEB Plan [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in projected benefit obligation	$ 8
Oncor Cash Balance Formula Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee's contribution match by employer		100.00%
Percentage of employee's contribution matched 100% by employer		6.00%
Oncor Traditional Retirement Plan Formula Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee's contribution match by employer		75.00%
Percentage of employee's contribution matched 100% by employer		6.00%

Employee Benefit Plans (Schedul

Employee Benefit Plans (Schedule Of Pension And OPEB Plan Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 90	$ 104	$ 147
Less amounts deferred principally as property or a regulatory asset	(13)	(27)	(69)
Net amounts recognized as operation and maintenance expense or other deductions	77	77	78
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	71	63	77
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 19	$ 41	$ 70

Employee Benefit Plans (Pension

Employee Benefit Plans (Pension and OPEB Costs Recognized as Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of net OPEB costs:
Net costs	$ 90	$ 104	$ 147
Pension Plan [Member]
Assumptions Used to Determine Net Periodic Pension and OPEB Costs:
Discount rate	3.13%	4.18%	3.54%
Expected return on plan assets	4.94%	5.42%	5.11%
Rate of compensation increase	4.64%	4.53%	4.46%
Components of net OPEB costs:
Service cost	$ 29	$ 25	$ 27
Interest cost	103	128	121
Expected return on assets	(109)	(119)	(120)
Amortization of net loss	48	29	49
Net costs	71	63	77
Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:
Net loss (gain)	61		67
Amortization of net loss	(48)	(29)	(49)
Total recognized as regulatory assets or other comprehensive income	13	(29)	18
Net amounts recognized as operation and maintenance expense or other deductions	$ 84	$ 34	$ 95
OPEB Plan [Member]
Assumptions Used to Determine Net Periodic Pension and OPEB Costs:
Discount rate	3.29%	4.41%	3.73%
Expected return on plan assets	5.90%	6.19%	6.20%
Components of net OPEB costs:
Service cost	$ 6	$ 6	$ 8
Interest cost	32	43	44
Expected return on assets	(8)	(7)	(9)
Amortization of prior service cost (credit)	(20)	(20)	(30)
Amortization of net loss	10	19	57
Curtailment cost (credit)	(1)
Net costs	19	41	70
Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:
Curtailment	2
Net loss (gain)	14	(22)	(177)
Amortization of net loss	(10)	(19)	(57)
Amortization of prior service cost (credit)	20	20	30
Total recognized as regulatory assets or other comprehensive income	26	(21)	(204)
Net amounts recognized as operation and maintenance expense or other deductions	$ 45	$ 20	$ (134)

Employee Benefit Plans (Assumpt

Employee Benefit Plans (Assumptions Used To Determine Benefit Obligations) (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.40%	3.13%	4.18%
Rate of compensation increase	4.80%	4.64%	4.53%
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.58%	3.29%	4.41%

Employee Benefit Plans (Change

Employee Benefit Plans (Change In Project Benefit Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of year	$ 3,400	$ 3,162
Service cost	29	25	$ 27
Interest cost	103	128	121
Participant contributions
Actuarial (gain) loss	302	367
Benefits paid	(165)	(164)
Curtailment
Settlements	(73)	(118)
Projected benefit obligation at end of year	3,596	3,400	3,162
Accumulated benefit obligation at end of year	3,433	3,283
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of year	999	1,006
Service cost	6	6	8
Interest cost	32	43	44
Participant contributions	18	19
Actuarial (gain) loss	20	(5)
Benefits paid	(63)	(70)
Curtailment	1
Settlements
Projected benefit obligation at end of year	1,013	999	$ 1,006
Accumulated benefit obligation at end of year

Employee Benefit Plans (Chang_2

Employee Benefit Plans (Change In Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 169	$ 76	$ 123
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets at beginning of year	2,494	2,249
Actual return (loss) on assets	350	486
Employer contributions	134	41	82
Participant contributions
Benefits paid	(165)	(164)
Settlements	(73)	(118)
Fair value of assets at end of year	2,740	2,494	2,249
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets at beginning of year	141	132
Actual return (loss) on assets	14	25
Employer contributions	35	35	41
Participant contributions	18	19
Benefits paid	(63)	(70)
Settlements
Fair value of assets at end of year	$ 145	$ 141	$ 132

Employee Benefit Plans (Funded

Employee Benefit Plans (Funded Status) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at end of year	$ (3,596)	$ (3,400)	$ (3,162)
Fair value of assets at end of year	2,740	2,494	2,249
Funded status at end of year	(856)	(906)
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at end of year	(1,013)	(999)	(1,006)
Fair value of assets at end of year	145	141	$ 132
Funded status at end of year	$ (868)	$ (858)

Employee Benefit Plans (Amounts

Employee Benefit Plans (Amounts Recognized In Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Other noncurrent liabilities	$ (1,808)	$ (1,834)
Accumulated other comprehensive net loss	(151)	(139)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	(5)	(5)
Other noncurrent liabilities	(863)	(901)
Net liability recognized	(868)	(906)
Other noncurrent assets	12
Net loss	556	531
Net regulatory assets recognized	556	531
Net assets recognized	568	531
Accumulated other comprehensive net loss	108	120
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	(14)	(15)
Other noncurrent liabilities	(854)	(843)
Net liability recognized	(868)	(858)
Net loss	132	129
Prior service cost (credit)	(16)	(37)
Net regulatory assets recognized	116	92
Net assets recognized	116	92
Accumulated other comprehensive net loss	$ 3	$ 1

Employee Benefit Plans (Sched_2

Employee Benefit Plans (Schedule Of Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Not Medicare Eligible [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care and prescription drug cost trend rate assumed for next year	6.90%	7.20%
Rate to which the cost trend is expected to decline (the ultimate trend rate)	4.50%	4.50%
Year that the rate reaches the ultimate trend rate	2029	2029
Medicare Eligible [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care and prescription drug cost trend rate assumed for next year	7.80%	8.00%
Rate to which the cost trend is expected to decline (the ultimate trend rate)	4.50%	4.50%
Year that the rate reaches the ultimate trend rate	2030	2029

Employee Benefit Plans (Sched_3

Employee Benefit Plans (Schedule Of Projected Benefit Obligations And Accumulated Benefit Obligations In Excess Of Plan Assets Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations	$ 3,596	$ 3,400
Accumulated benefit obligations	3,433	3,283
Plan assets	2,740	2,494
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	1,013	999
Plan assets	$ 145	$ 141

Employee Benefit Plans (Sched_4

Employee Benefit Plans (Schedule Of Target Asset Allocation Ranges By Asset Category) (Details)	Dec. 31, 2020
International Equities [Member] | Recoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	13.00%
International Equities [Member] | Recoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	21.00%
International Equities [Member] | Nonrecoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	6.00%
International Equities [Member] | Nonrecoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	12.00%
US Equities [Member] | Recoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	16.00%
US Equities [Member] | Recoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	24.00%
US Equities [Member] | Nonrecoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	8.00%
US Equities [Member] | Nonrecoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	14.00%
Real Estate [Member] | Recoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	3.00%
Real Estate [Member] | Recoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	7.00%
Credit Strategies [Member] | Recoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	5.00%
Credit Strategies [Member] | Recoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	10.00%
Credit Strategies [Member] | Nonrecoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	5.00%
Credit Strategies [Member] | Nonrecoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	9.00%
Fixed Income [Member] | Recoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	45.00%
Fixed Income [Member] | Recoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	55.00%
Fixed Income [Member] | Nonrecoverable [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	68.00%
Fixed Income [Member] | Nonrecoverable [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	78.00%

Employee Benefit Plans (Sched_5

Employee Benefit Plans (Schedule Of Assets Fair Value Measured On Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 2,740	$ 2,494	$ 2,249
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	145	141	$ 132
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	550	484
Fair Value, Inputs, Level 1 [Member] | OPEB Plan [Member] | Accounting Standards Update 2015-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	77	80
Fair Value, Inputs, Level 1 [Member] | Interest-bearing Cash [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	9	6
Fair Value, Inputs, Level 1 [Member] | US Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	220	194
Fair Value, Inputs, Level 1 [Member] | US Equities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	24	24
Fair Value, Inputs, Level 1 [Member] | International Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	330	290
Fair Value, Inputs, Level 1 [Member] | International Equities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	25	28
Fair Value, Inputs, Level 1 [Member] | Other [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	19	22
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,015	1,121
Fair Value, Inputs, Level 2 [Member] | OPEB Plan [Member] | Accounting Standards Update 2015-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	38	36
Fair Value, Inputs, Level 2 [Member] | US Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1	2
Fair Value, Inputs, Level 2 [Member] | International Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1	1
Fair Value, Inputs, Level 2 [Member] | Corporate Bond Securities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	910	908
Fair Value, Inputs, Level 2 [Member] | Corporate Bond Securities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	34	31
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	46	147
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1	3
Fair Value, Inputs, Level 2 [Member] | Other [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	57	63
Fair Value, Inputs, Level 2 [Member] | Other [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	3	2
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets		3
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets		3
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,565	1,608
Fair Value, Inputs, Level 1, 2 and 3 [Member] | OPEB Plan [Member] | Accounting Standards Update 2015-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	115	116
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Interest-bearing Cash [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	9	6
Fair Value, Inputs, Level 1, 2 and 3 [Member] | US Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	221	196
Fair Value, Inputs, Level 1, 2 and 3 [Member] | US Equities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	24	24
Fair Value, Inputs, Level 1, 2 and 3 [Member] | International Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	331	291
Fair Value, Inputs, Level 1, 2 and 3 [Member] | International Equities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	25	28
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Corporate Bond Securities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	910	908
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Corporate Bond Securities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	34	31
Fair Value, Inputs, Level 1, 2 and 3 [Member] | US Treasury Securities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	46	147
Fair Value, Inputs, Level 1, 2 and 3 [Member] | US Treasury Securities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1	3
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Other [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	57	63
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Other [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	22	24
Fair Value, Inputs, Level 1, 2 and 3 [Member] | Real Estate [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets		3
NAV [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,175	886
NAV [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 30	$ 25

Employee Benefit Plans (Sched_6

Employee Benefit Plans (Schedule Of Expected Long-Term Rate Of Return On Assets Assumptions) (Details)	12 Months Ended
	Dec. 31, 2020
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	4.57%
Pension Plan [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	7.58%
Pension Plan [Member] | US Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	6.50%
Pension Plan [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.60%
Pension Plan [Member] | Credit Strategies [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	3.90%
Pension Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	2.32%
Pension Plan [Member] | Oncor Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	3.75%
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.24%
OPEB Plan [Member] | 401(h) Accounts [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.59%
OPEB Plan [Member] | Life Insurance VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.10%
OPEB Plan [Member] | Union VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.10%
OPEB Plan [Member] | Non-union VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	1.10%
OPEB Plan [Member] | Shared retiree VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	1.10%
OPEB Plan [Member] | Vistra Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	4.20%

Employee Benefit Plans (Sched_7

Employee Benefit Plans (Schedule Of Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total contributions	$ 169	$ 76	$ 123
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions	134	41	82
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions	$ 35	$ 35	$ 41

Employee Benefit Plans (Sched_8

Employee Benefit Plans (Schedule Of Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2020USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	$ 186
2022	189
2023	192
2024	195
2025	197
2026-30	975
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	49
2022	51
2023	52
2024	53
2025	54
2026-30	$ 271

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	0
SARs Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend accrual compensation expense			$ 15,000,000
SARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized dividend accretion and interest	$ 0	$ 4,000,000

Related-Party Transactions (Nar

Related-Party Transactions (Narrative) (Details) - USD ($) $ in Millions	Mar. 08, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Revenue from contracts		$ 4,511	$ 4,347	$ 4,101
Purchases from related party		$ 975	$ 1,005	$ 962
Sponsor Group [Member]
Related Party Transaction [Line Items]
Equity in existing vendor	16.00%
Sponsor Group [Member]
Related Party Transaction [Line Items]
Substation monitoring and switching services	$ 35
Sponsor Group [Member] | Capitalized [Member]
Related Party Transaction [Line Items]
Substation monitoring and switching services	33
Sponsor Group [Member] | Operating And Maintenance Expense [Member]
Related Party Transaction [Line Items]
Substation monitoring and switching services	$ 2

Related-Party Transactions (Sch

Related-Party Transactions (Schedule Of Amounts Payable To (Receivables From) Related Parties) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Net payable (receivable)	$ 16	$ 19
Texas [Member]
Related Party Transaction [Line Items]
Texas margin tax payable	23	22
Federal [Member]
Related Party Transaction [Line Items]
Federal income taxes payable (receivable)	(7)	(3)
Sempra Texas Holdings [Member]
Related Party Transaction [Line Items]
Net payable (receivable)	17	20
Sempra Texas Holdings [Member] | Texas [Member]
Related Party Transaction [Line Items]
Texas margin tax payable	23	22
Sempra Texas Holdings [Member] | Federal [Member]
Related Party Transaction [Line Items]
Federal income taxes payable (receivable)	(6)	(2)
Texas Transmission and Investment LLC [Member]
Related Party Transaction [Line Items]
Net payable (receivable)	(1)	(1)
Texas Transmission and Investment LLC [Member] | Federal [Member]
Related Party Transaction [Line Items]
Federal income taxes payable (receivable)	$ (1)	$ (1)

Related-Party Transactions (S_2

Related-Party Transactions (Schedule Of Cash Payments Made To (Received From) Related Parties) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Federal income taxes	$ 56	$ 50
Texas margin tax	22	21
Total payments (receipts)	78	71
Sempra Texas Holdings [Member]
Related Party Transaction [Line Items]
Federal income taxes	45	59
Texas margin tax	22	21
Total payments (receipts)	67	80
EFH Corp [Member]
Related Party Transaction [Line Items]
Federal income taxes		(19)
Total payments (receipts)		(19)
Texas Transmission and Investment LLC [Member]
Related Party Transaction [Line Items]
Federal income taxes	11	10
Total payments (receipts)	$ 11	$ 10

Supplementary Financial Infor_3

Supplementary Financial Information (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Financial Information [Line Items]
Face value of life insurance policies	$ 181	$ 172
Net cash surrender values	$ 97	$ 95
Depreciation expense as percentage of average depreciable property	2.70%	2.70%	2.80%
Aggregate amortization expenses	$ 62	$ 52	$ 50
Goodwill	$ 4,740	$ 4,740
Trade Accounts Receivable [Member] | Nonaffiliated REP [Member]
Supplemental Financial Information [Line Items]
Concentration risk percentage		15.00%
Trade Accounts Receivable [Member] | Second Nonaffiliated REP [Member]
Supplemental Financial Information [Line Items]
Concentration risk percentage		11.00%
Land Easements [Member]
Supplemental Financial Information [Line Items]
Weighted average remaining useful life	84 years
Capitalized Software [Member]
Supplemental Financial Information [Line Items]
Weighted average remaining useful life	9 years

Supplementary Financial Infor_4

Supplementary Financial Information (Schedule Of Other Deductions And (Income)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Professional fees	$ 6	$ 10	$ 12
Sempra Acquisition related costs			12
InfraREIT Acquisition related costs		9
Recoverable pension and OPEB - non-service	55	57	53
Non-recoverable pension and OPEB (Note 10)	4	4	6
AFUDC equity income	(29)	(10)
Interest income	(4)	(5)	(1)
Other			2
Other	1	(2)
Total other deductions and (income) - net	$ 33	$ 63	$ 84

Supplementary Financial Infor_5

Supplementary Financial Information (Schedule Of Interest Expense And Related Charges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Interest	$ 413	$ 382	$ 358
Amortization of debt issuance costs and discounts	11	9	6
Less allowance for funds used during construction – capitalized interest portion	(19)	(16)	(13)
Total interest expense and related charges	$ 405	$ 375	$ 351

Supplementary Financial Infor_6

Supplementary Financial Information (Schedule Of Trade Accounts And Other Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Supplementary Financial Information [Abstract]
Gross trade accounts and other receivables	$ 767	$ 666
Allowance for uncollectible accounts	(7)	(5)
Trade accounts receivable - net	$ 760	$ 661

Supplementary Financial Infor_7

Supplementary Financial Information (Summary of Investments And Other Property) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Supplementary Financial Information [Abstract]
Assets related to employee benefit plans	$ 124	$ 119
Land	16	12
Other	2	2
Total investments and other property	$ 142	$ 133

Supplementary Financial Infor_8

Supplementary Financial Information (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant and Equipment [Line Items]
Total assets in service	$ 28,948	$ 26,749
Less accumulated depreciation	8,336	7,986
Net of accumulated depreciation	20,612	18,763
Construction work in progress	593	585
Held for future use	20	22
Property, plant and equipment - net	21,225	19,370
Distribution [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 14,937	14,007
Composite depreciation rate	2.50%
Avg. life	39 years 4 months 24 days
Transmission [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 12,156	11,094
Composite depreciation rate	2.90%
Avg. life	34 years 9 months 18 days
Other Assets [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 1,855	$ 1,648
Composite depreciation rate	6.70%
Avg. life	14 years 10 months 24 days

Supplementary Financial Infor_9

Supplementary Financial Information (Schedule Of Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,650	$ 1,508
Accumulated Amortization	596	537
Net	1,054	971
Land Easements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	623	575
Accumulated Amortization	112	107
Net	511	468
Capitalized Software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,027	933
Accumulated Amortization	484	430
Net	$ 543	$ 503

Supplementary Financial Info_10

Supplementary Financial Information (Schedule Of Estimated Aggregate Amortization Expenses) (Details) $ in Millions	Dec. 31, 2020USD ($)
Supplementary Financial Information [Abstract]
2021	$ 68
2022	68
2023	68
2024	67
2024	$ 67

Supplementary Financial Info_11

Supplementary Financial Information (Schedule Of Operating Lease, Third Party Joint Project And Other Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Supplementary Financial Information [Abstract]
Retirement plans and other employee benefits	$ 124	$ 66
Operating lease liabilities	5	6
Investment tax credits	100	4
Other	76	70
Total operating lease, third party joint project and other obligations	$ 305	$ 146

Supplementary Financial Info_12

Supplementary Financial Information (Schedule Of Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Interest	$ 406	$ 368	$ 368
Less capitalized interest	(19)	(16)	(13)
Interest payments (net of amounts capitalized)	387	352	355
Federal	87	56	50
State	22	22	21
Total payments (receipts) in lieu of income taxes	109	78	71
Noncash increase in operating lease obligations for ROU assets	72	38
Assets acquired		2,547
Liabilities assumed		(1,223)
Cash paid		1,324
Noncash construction expenditures	$ 254	$ 278	$ 174

Supplementary Financial Info_13

Supplementary Financial Information (Schedule Of Quarterly Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Operating revenues (Note 4)	$ 1,117	$ 1,232	$ 1,090	$ 1,072	$ 1,079	$ 1,211	$ 1,041	$ 1,016
Operating income	250	362	285	242	236	369	253	216	$ 1,139	$ 1,074	$ 945
Net income	$ 148	$ 258	$ 176	$ 131	$ 133	$ 263	$ 139	$ 116	$ 713	$ 651	$ 545

Acquisition Activity (Narrative

Acquisition Activity (Narrative) (Details) - USD ($) $ in Millions	May 16, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Repayment of debt											$ 1,164	$ 1,094	$ 825
InfraREIT Acquisition related costs												9
Revenue from contracts											4,511	4,347	4,101
Net income		$ 148	$ 258	$ 176	$ 131	$ 133	$ 263	$ 139	$ 116		$ 713	651	$ 545
Secured Debt [Member]
Business Acquisition [Line Items]
Outstanding debt acquired	$ 351
InfraREIT [Member]
Business Acquisition [Line Items]
Management agreement termination fee	40
Repayment of debt	602
Outstanding debt acquired	$ 953
Transmission of assets						$ 2,547				$ 2,547		$ 2,547
Revenue from contracts										250
Net income										$ 106

Acquisition Activity (Total Pur

Acquisition Activity (Total Purchase Price Paid) (Details) - USD ($) $ in Millions	Mar. 31, 2020	May 16, 2019	Dec. 31, 2019	Dec. 31, 2019
Purchase of outstanding InfraREIT shares and units				$ 1,324
InfraREIT [Member]
Purchase of outstanding InfraREIT shares and units	$ 1,275	$ 1,275
Certain transaction costs of InfraREIT paid by Oncor through June 30, 2019	53
Total purchase price paid through June 30, 2019	1,328
Adjustments made in the period from June 30, 2019 through March 31, 2020	(4)
Total purchase price paid	$ 1,324	$ 1,324	$ 1,324
Management termination fee			$ 40

Acquisition Activity (Assets An

Acquisition Activity (Assets And Liabilities Assumed) (Details) - USD ($) $ in Millions	Mar. 31, 2020	May 16, 2019	Dec. 31, 2019	Dec. 31, 2020
Goodwill			$ 4,740	$ 4,740
InfraREIT [Member]
Current assets			45
Property, plant and equipment - net			1,800
Goodwill			676	$ 676
Regulatory assets			16
Other noncurrent assets			10
Total assets acquired			2,547
Short-term debt			115
Other current liabilities			24
Regulatory liabilities			148
Liability in lieu of deferred income taxes			97
Long-term debt, including due currently			839
Total liabilities assumed			1,223
Net assets acquired			1,324
Total purchase price paid	$ 1,324	$ 1,324	$ 1,324

Acquisition Activity (Pro Forma

Acquisition Activity (Pro Forma Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
InfraREIT [Member]
Oncor Consolidated Pro Forma Revenues	$ 4,431	$ 4,318