Oncor Electric Delivery 10-K 27 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 27, 2020	Dec. 31, 2018	Dec. 31, 2017
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
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
Entity Shell Company	false
Entity Public Float	$ 0
Capital account, interests outstanding	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	2019
Document Fiscal Period Focus	FY
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Statements Of Consolidated Income [Abstract]
Operating revenues (Note 4)	$ 4,347	$ 4,101	$ 3,958
Operating expenses:
Wholesale transmission service	1,005	962	929
Operation and maintenance (Note 12)	899	875	731
Depreciation and amortization	723	671	762
Provision in lieu of income taxes (Notes 1, 5 and 12)	138	152	266
Taxes other than amounts related to income taxes	508	496	462
Total operating expenses	3,273	3,156	3,150
Operating income	1,074	945	808
Other deductions and (income) - net (Note 13)	63	84	46
Nonoperating provision (benefit) in lieu of income taxes (Note 5)	(15)	(35)	1
Interest expense and related charges (Note 13)	375	351	342
Net income	$ 651	$ 545	$ 419

Statements Of Consolidated Comp

Statements Of Consolidated Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statements Of Consolidated Comprehensive Income [Abstract]
Net income	$ 651	$ 545	$ 419
Other comprehensive income (loss):
Cash flow hedges – derivative value net loss recognized in net income (net of tax expense of $-, $1 and $1) (Note 1)	2	2	2
Defined benefit pension plans (net of tax expense of $-, $45 and $4) (Note 10)	27	(65)	8
Total other comprehensive income (loss)	29	(63)	10
Comprehensive income	$ 680	$ 482	$ 429

Statements Of Consolidated Co_2

Statements Of Consolidated Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statements Of Consolidated Comprehensive Income [Abstract]
Cash flow hedges - derivative value net loss recognized in net income, tax expense		$ 1	$ 1
Defined benefit pension plans- net tax benefit		$ 45	$ 4

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows - operating activities:
Net income	$ 651	$ 545	$ 419
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization, including regulatory amortization	806	777	815
Provision in lieu of deferred income taxes - net	55	18	309
Other - net	(3)	(3)	(2)
Changes in operating assets and liabilities:
Accounts receivable - trade	(53)	68	(76)
Inventories	(30)	(25)	(1)
Accounts payable - trade	21	30	(11)
Regulatory accounts related to reconcilable tariffs (Note 3)	(44)	66	29
Other - assets	(204)	33	54
Other - liabilities	76	(27)	(77)
Cash provided by operating activities	1,275	1,482	1,459
Cash flows - financing activities:
Issuances of long-term debt (Note 7)	2,460	1,150	600
Repayments of long-term debt (Note 7)	(1,094)	(825)	(324)
Proceeds of business acquisition bridge loan (Note 6)	600
Payment of business acquisition bridge loan (Note 6)	(600)
Net (decrease) increase in short-term borrowings (Note 6)	(882)	(137)	161
Capital contributions from members (Note 9)	1,978	284
Distributions to members (Note 9)	(319)	(209)	(237)
Debt discount, premium, financing and reacquisition costs - net	(39)	(14)	(10)
Cash provided by financing activities	2,104	249	190
Cash flows - investing activities:
Capital expenditures (Note 12)	(2,097)	(1,767)	(1,631)
Business acquisition (Note 2)	(1,324)		(25)
Other - net	43	18	12
Cash used in investing activities	(3,378)	(1,749)	(1,644)
Net change in cash and cash equivalents	1	(18)	5
Cash and cash equivalents - beginning balance	3	21	16
Cash and cash equivalents - ending balance	$ 4	$ 3	$ 21

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 4	$ 3
Trade accounts receivable - net (Note 13)	661	559
Amounts receivable from members related to income taxes (Note 12)	3
Materials and supplies inventories - at average cost	148	116
Prepayments and other current assets	96	94
Total current assets	912	772
Investments and other property (Note 13)	133	120
Property, plant and equipment - net (Note 13)	19,370	16,090
Goodwill (Notes 1 and 13)	4,740	4,064
Regulatory assets (Note 3)	1,775	1,691
Operating lease ROU and other assets (Note 1)	106	15
Total assets	27,036	22,752
Current liabilities:
Short-term borrowings (Note 6)	46	813
Long-term debt due currently (Note 7)	608	600
Trade accounts payable (Note 12)	394	300
Amounts payable to members related to income taxes (Note 12)	22	26
Accrued taxes other than amounts related to income	236	199
Accrued interest	83	68
Operating lease and other current liabilities (Note 8)	237	209
Total current liabilities	1,626	2,215
Long-term debt, less amounts due currently (Note 7)	8,017	5,835
Liability in lieu of deferred income taxes (Notes 1,5 and 12)	1,821	1,602
Regulatory liabilities (Note 3)	2,793	2,697
Employee benefit, operating lease and other obligations (Notes 10 and 13)	1,980	1,943
Total liabilities	16,237	14,292
Commitments and contingencies (Note 8)
Membership interests (Note 9):
Capital account ― number of interests outstanding 2019 and 2018 – 635,000,000	10,938	8,624
Accumulated other comprehensive loss	(139)	(164)
Total membership interests	10,799	8,460
Total liabilities and membership interests	$ 27,036	$ 22,752

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets [Abstract]
Capital account, interests outstanding	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, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capital account:
Balance at beginning of period		$ 8,624		$ 8,004	$ 8,624	$ 8,004	$ 7,822
Net income	$ 133	116	$ 119	89	651	545	419
Capital contributions from members (Note 9)					1,978	284
Distributions to members (Note 9)					(319)	(209)	(237)
Balance at end of period (number of units outstanding: 2019, 2018 and 2017 – 635,000,000)	10,938		8,624		10,938	8,624	8,004
Accumulated other comprehensive income (loss) net of tax effects (Note 9):
Balance at beginning of period		$ (164)		$ (101)	(164)	(101)	(111)
Net effects of cash flow hedges (net of tax expense of $1, $1 and $1)					2	2	2
Defined benefit pension plans (net of tax expense of $-, $45 and $4) (Note 10)					27	(65)	8
ASU 2018-02 stranded tax effects (Note 1)					(4)
Balance at end of period	(139)		(164)		(139)	(164)	(101)
Total membership interests at end of period	$ 10,799		$ 8,460		$ 10,799	$ 8,460	$ 7,903

Statements Of Consolidated Me_2

Statements Of Consolidated Membership Interests (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	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	$ 1	$ 1
Defined benefit pension plans- net tax benefit		$ 45

Description Of Business And Sig

Description Of Business And Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
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 for the fiscal year ended December 31, 2019, include the results of our wholly owned indirect subsidiary, NTU, which is a regulated utility that provides electricity transmission delivery service in the north-central, western and panhandle regions of Texas. We acquired NTU as part of the InfraREIT Acquisition that closed on May 16, 2019.  Ring-Fencing Measures  Since 200 7 , 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 2008 sale of 19.75% of Oncor’s equity interests to Texas Transmission.  In March 2018, 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.  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 the officer being employed by Oncor. 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 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 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 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 stock 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 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 stock 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 4 for additional information regarding revenues.  Goodwill  The increase in goodwill to $4,740 million at December 31, 2019 from $4,064 million at December 31, 2018 is due to the InfraREIT Acquisition. See Note 2 for more information on the InfraREIT Acquisition.  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.  If at the assessment date our carrying value exceeds our estimated fair value (enterprise value), then the estimated enterprise value is compared to the estimated fair values of our operating assets (including identifiable intangible assets) and liabilities at the assessment date. The resultant implied goodwill amount is compared to the recorded goodwill amount. Any excess of the recorded goodwill amount over the implied goodwill amount is written off as an impairment charge.  In each of 2019, 2018 and 2017, 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 additional testing for impairment was required and n o impairments were recognized .  Provision in Lieu of Income Taxes  Our tax sharing agreement with Oncor Holdings, Texas Transmission and STH (as successor to EFH Corp.) 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 5.  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 10 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 and prudence and possible disallowance. 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 3 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 13 for detail of amounts reducing interest expense and increasing other income.  Cash and Cash Equivalents  For purposes of reporting cash and cash equivalents, temporary cash investments purchased with an original maturity of three months or less 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 10) and long-term debt (see Note 7).  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 842, “Leases” – In February 2016, the FASB issued ASU 2016-02 which created FASB Topic 842, Leases (Topic 842). Topic 842 amends previous GAAP to require the balance sheet recognition of substantially all lease assets and liabilities, including operating leases. Operating lease liabilities are not classified as debt for GAAP purposes under Topic 842 and are not treated as debt for our regulatory purposes. All of Oncor’s existing leases meet the definition of an operating lease. Under the new rules, the recognition of any finance leases (previously known as capital leases) on the balance sheet are classified as debt for both GAAP and regulatory capital structure purposes (see Note 8 for details) similar to the previous capital lease treatment.  We adopted Topic 842 on January 1, 2019, using the optional transition method to apply the new guidance prospectively and not restate comparative periods. We elected the package of practical expedients that permits us to not reassess (a) whether a contract is or contains a lease, (b) lease classification or (c) determination of initial direct costs, which allows us to carry forward accounting conclusions under previous GAAP on contracts that commenced prior to adoption of the lease standard. We also elected the land easement practical expedient, which allows us to continue to account for pre-existing land easements under our accounting policy that existed before adoption of the lease standard. We did not elect the practical expedient to use hindsight in making judgments when determining the lease term.  The adoption of Topic 842 affects our balance sheet, as our contracts for office space, service centers and fleet vehicles are operating leases. The following table shows the increases on our balance sheet at January 1, 2019 from the initial adoption of Topic 842.     At January 1, 2019  Operating Leases:  ROU assets:  Operating lease ROU and other assets $ 82   Lease liabilities:  Operating lease and other current liabilities $ 26  Employee benefit, operating lease and other obligations 56  Total operating lease liabilities $ 82  Topic 220, “Income Statement—Reporting Comprehensive Income” amended by ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” – In February 2018, the FASB issued ASU 2018-02, an amendment to Topic 220. Under ASU 2018-02, an entity is required to provide certain disclosures regarding stranded tax effects, including its accounting policy related to releasing the income tax effects from accumulated other comprehensive income (AOCI). We elected to reclassify stranded tax effects resulting from the TCJA from AOCI to capital accounts. Our stranded tax effects in AOCI, which are related to previous interest rate cash flow hedges, were $4 million and increased our capital account upon reclassification. We adopted the standard on a prospective basis effective January 1, 2019.  Topic 326, “Financial Instruments—Credit Losses” – In June 2016 the FASB issued ASU No. 2016-13, which changes how entities account for credit losses on receivables and certain other 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. Topic 326 is required to be adopted in the first quarter of fiscal 2020 with earlier adoption permitted. We adopted on a prospective basis effective January 1, 2020. The adoption of the new standard did not have a material impact on our consolidated financial statements.  Topic 350, “Intangibles, Goodwill and Other —Internal-Use Software (Subtopic 40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service ” – In August 2018, the FASB issued ASU 2018-15 which clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is required to be adopted in the first quarter of fiscal 2020 with earlier adoption permitted. We have early adopted on a prospective basis effective July 1, 2019. The early adoption did not have a material effect on our consolidated financial statements.

Acquisition Activity

Acquisition Activity	12 Months Ended
	Dec. 31, 2019
Acquisition Activity [Abstract]
ACQUISITION ACTIVITY	 2. ACQUISITION ACTIVITY  InfraREIT Acquisition  On May 16, 2019, we completed the InfraREIT Acquisition, pursuant to which we acquired all of the equity interests of InfraREIT and its subsidiary, InfraREIT Partners. The InfraREIT Acquisition occurred through the merger of InfraREIT with and into a newly formed wholly owned subsidiary of Oncor, followed by the merger of another newly formed wholly owned subsidiary of Oncor with and into InfraREIT Partners. The stockholders of InfraREIT and the limited partners of InfraREIT Partners received $21.00 in cash per share of common stock or limited partnership unit, as applicable, resulting in a total cash consideration of $1,275 million . 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 million.  In connection with and immediately following the closing of the InfraREIT Acquisition, on May 16, 2019, 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 $351 million principal amount of InfraREIT subsidiary debt for new Oncor senior secured debt, as discussed in more detail in Notes 6 and 7.  On May 15, 2019, in connection with the InfraREIT Acquisition, we received capital contributions in an aggregate amount of $1,330 million from Sempra and certain indirect equity holders of Texas Transmission to fund the cash consideration and certain transaction expenses. As a condition to the InfraREIT Acquisition, SDTS, and SDTS’s tenant, SU, completed the SDTS-SU Asset Exchange immediately prior to the closing of the InfraREIT Acquisition, pursuant to which SDTS exchanged certain of its south Texas assets for certain north Texas assets owned by SU. The north Texas assets acquired by SDTS consisted of certain real property and other assets owned by SU and used in the electric transmission and distribution business in central, north and west Texas, as well as equity interests in GS Project Entity, L.L.C., a Texas limited liability company that was merged with and into SDTS. The south Texas assets acquired by SU consisted of real property and other assets near the Texas-Mexico border. As a result of the InfraREIT Acquisition closing, we and our subsidiary NTU now own all of the assets and projects in the north, central, west and panhandle regions of Texas held by SDTS and SU immediately prior to the InfraREIT Acquisition, and Sharyland owns the assets that were held by SU and SDTS in south Texas immediately prior to the InfraREIT Acquisition. The assets we acquired include approximately 1,575 miles of transmission lines, including 1,235 circuit miles of 345 kV transmission lines and approximately 340 circuit miles of 138 kV transmission lines. The north, central, and west Texas transmission system acquired by us in the transaction is directly connected to approximately 20 operational generation facilities totaling approximately 3,900 MW and serves over 50 substations. We also acquired various projects in the north, central, west and panhandle regions of Texas, including a joint project with Lubbock Power & Light (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. Costs and investments for this project are ultimately to be split between Oncor and LP&L, with Oncor performing the construction and invoicing LP&L for its portion of the costs on a monthly basis. In addition, as a condition to the closing of the SDTS-SU Asset Exchange, Sempra acquired an indirect 50 percent interest in Sharyland Holdings, 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 agreement governing the SDTS-SU Asset Exchange and 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.  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 and the allocation of the total purchase price paid to the identifiable assets acquired and liabilities assumed. The purchase price allocation is preliminary and the allocation to each identifiable asset acquired and liability assumed may change based upon the receipt of more detailed information and additional analyses related primarily to income tax liabilities. In the year ended December 31, 2019, we made various purchase price allocation adjustments related primarily to working capital accounts resulting in an $11 million reduction to goodwill. We currently expect the final purchase price allocation will be completed no later than the second quarter of 2020.     The total purchase price paid was comprised of the following   Purchase of outstanding InfraREIT shares and units $ 1,275  Certain transaction costs of InfraREIT paid by Oncor (a) 49  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 $9 million in 2019. Our statements of consolidated income include revenues and net income of the acquired business totaling $156 million and $58 million, respectively, since the May 16, 2019 acquisition date.  Unaudited Pro Forma Financial Information  The following unaudited pro forma financial information for the year 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.   Sharyland 2017 Asset Exchange  In November, 2017, we exchanged approximately $383 million of our transmission assets, consisting of 517 circuit miles of 345 kV transmission lines, and approximately $25 million in cash for approximately $408 million of the Sharyland Entities’ distribution assets (constituting substantially all of their electricity distribution business) and certain of their transmission assets pursuant to the Sharyland 2017 Agreement. The Sharyland 2017 Asset Exchange expanded our customer base in west Texas and provides some potential growth opportunities for our distribution network. The exchange of assets between Oncor and the Sharyland Entities was structured to qualify, in part, as a simultaneous tax deferred like kind exchange to the extent that the assets exchanged are of “like kind” (within the meaning of section 1031 of the Code). The Sharyland 2017 Asset Exchange did not have a material effect on our results of operations, financial position or cash flows.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2019
Regulatory Matters [Abstract]
REGULATORY MATTERS	3. 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, 2019 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, 2019 2019 2018   Regulatory assets:  Employee retirement liability (a)(b)(c) To be determined $ 623 $ 648  Employee retirement costs being amortized 8 years 262 297  Employee retirement costs incurred since the last rate review period (b) To be determined 79 73  Self-insurance reserve (primarily storm recovery costs) being amortized 8 years 309 351  Self-insurance reserve incurred since the last rate review period (primarily storm related) (b) To be determined 238 59  Securities reacquisition costs Lives of related debt 29 10  Deferred conventional meter and metering facilities depreciation 1 year 15 36  Under-recovered AMS costs 8 years 170 185  Energy efficiency performance bonus (a) 1 year or less 9 7  Wholesale distribution substation service To be determined 34 15  Other regulatory assets Various 7 10  Total regulatory assets 1,775 1,691   Regulatory liabilities:  Estimated net removal costs Lives of related assets 1,178 1,023  Excess deferred taxes Primarily over lives of related assets 1,574 1,571  Over-recovered wholesale transmission service expense (a) 1 year or less 30 89  Other regulatory liabilities Various 11 14  Total regulatory liabilities 2,793 2,697  Net regulatory assets (liabilities) $ (1,018) $ (1,006) ____________ (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.   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 the Sempra-Sharyland Transaction. For more information on these transactions, see Note 2.  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 2018, we reached an unopposed stipulation regarding an overall settlement of the TCJA impacts. The settlement included, on an annual basis, $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. Unprotected excess deferred federal income taxes are being refunded over a ten-year period and the protected excess deferred federal income taxes are being refunded 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.  DCRF (PUCT Docket No. 49427)  On April 8, 2019, we filed with the PUCT, as well as with cities with original jurisdiction over our rates, an application for approval of an updated DCRF. The DCRF allows us to recover, primarily through our tariff for retail delivery service, certain costs related to our distribution investments. In our DCRF application, we requested a $29 million increase in annual distribution revenues related to 2018 distribution investments. On May 30, 2019, a stipulated settlement agreement among the parties to the proceeding was reached that included a $25 million increase in annual distribution revenues, and, on June 10, 2019, interim rates based on the stipulated settlement agreement were authorized to begin on September 1, 2019. On September 12, 2019, the PUCT issued a final order implementing the settlement agreement and rates.  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.  2017 Rate Review (PUCT Docket No. 46957)  In response to resolutions passed by numerous cities with original jurisdiction over electric utility rates, we filed rate review proceedings with the PUCT and original jurisdiction cities in our service territory in March 2017 based on a January 1, 2016 to December 31, 2016 test year.  In July 2017, we and certain parties to our rate review agreed to a settlement of that rate review, and on August 2, 2017 a settlement agreement was filed with the PUCT that settled all issues in the docket. On October 13, 2017, the PUCT issued an order approving the settlement of the rate review, subject to closing of the Sharyland Asset Exchange, which closed on November 9, 2017. As a result of the closing, the contingency in the PUCT Docket No. 46957 order was met and our new rates as set forth in that order took effect on November 27, 2017. The order also required us to record as a regulatory liability, instead of revenue, the amount that we collected through our approved tariffs for federal income taxes that was above the new corporate federal income rate. Other significant findings in the order include a change in our authorized return on equity to 9.80% and a change in our authorized regulatory capital structure to 57.5% debt to 42.5% equity. Our previous authorized return on equity was 10.25% and our previous authorized regulatory capital structure was 60% debt to 40% equity. The PUCT order required us to record a regulatory liability from November 27, 2017 until the new authorized regulatory capital structure was met to reflect our actual capitalization prior to achieving the authorized capital structure. Our authorized regulatory capital structure was met in May 2018, and therefore we ceased accruing amounts to the capital structure refund regulatory liability as of that time. The regulatory liability of $6 million was approved on September 14, 2018 in PUCT Docket No. 48522, and the liability was subsequently returned to customers in September 2018.  Also, in accordance with the rate review final order, effective November 27, 2017, the AMS surcharge ceased and ongoing AMS costs are being recovered through base rates which include the recovery of the AMS regulatory asset over a 10-year period. We continue to recover previously approved retired conventional meters over time as a regulatory asset.  Sharyland 2017 Asset Exchange (PUCT Docket No. 47469)  On July 21, 2017, we entered into the Sharyland 2017 Agreement, which provided for us to exchange certain of our transmission assets and cash for certain of the Sharyland Entities’ distribution assets (constituting substantially all of their electricity distribution business) and certain of their transmission assets. On October 13, 2017, the PUCT issued an order approving the Sharyland 2017 Asset Exchange and on November 9, 2017, the parties consummated the transaction. For more information on the Sharyland 2017 Agreement and the Sharyland 2017 Asset Exchange, see Note 2.  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, 2019
Revenues [Abstract]
REVENUES	4. 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 2019 and 2018, the PUCT approved a $9 million and $7 million bonus that we recognized in revenues in 2019 and 2018, respectively.  Disaggregation of Revenues  The following table reflects electric delivery revenues disaggregated by tariff:   Year Ended December 31,  2019 2018  Operating revenues  Revenues contributing to earnings:  Distribution base revenues $ 2,143 $ 2,139  Transmission base revenues (TCOS revenues)  Billed to third-party wholesale customers 681 548  Billed to REPs serving Oncor distribution customers, through TCRF 391 310  Total transmission base revenues 1,072 858  Other miscellaneous revenues 77 71  Total revenues contributing to earnings 3,292 3,068   Revenues collected for pass-through expenses:  TCRF - third-party wholesale transmission service 1,005 962  EECRF and other regulatory charges 50 71  Revenues collected for pass-through expenses 1,055 1,033   Total operating revenues $ 4,347 $ 4,101  Customers  Our distribution customers consist of approximately 90 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 counterparties represented 23% and 18% of our total operating revenues for the year ended 2019, 23% and 19% for the year ended 2018 and 22% and 18% for the year ended 2017. 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  Expenses which are allowed to be passed-through to customers (primarily, third party wholesale transmission service and energy efficiency program costs) are generally recognized as revenue at the time the costs are incurred. 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.

Provision In Lieu Of Income Tax

Provision In Lieu Of Income Taxes	12 Months Ended
	Dec. 31, 2019
Provision In Lieu Of Income Taxes [Abstract]
PROVISION IN LIEU OF INCOME TAXES	5. PROVISION IN LIEU OF INCOME TAXES  Tax Cuts and Jobs Act (TCJA)  On December 22, 2017, the TCJA was signed into law. Substantially all of the provisions of the TCJA were effective for our taxable years beginning January 1, 2018. The TCJA included significant changes to the Code, including amendments which significantly change the taxation of business entities and includes specific provisions related to regulated public utilities such as Oncor. The most significant TCJA change that impacts us is the reduction in the corporate federal income tax rate from 35% to 21% . The specific provisions related to regulated public utilities in the TCJA applicable to us include the continued deductibility of interest expense, the elimination of bonus depreciation on certain property acquired after September 27, 2017 and certain rate normalization requirements for accelerated depreciation benefits.  Changes in the Code from the TCJA had a material impact on our financial statements in 2017. Under GAAP, specifically Topic 740, Income Taxes, the tax effects of changes in tax laws must be recognized when the law is enacted, or December 22, 2017 for the TCJA. Topic 740 also requires deferred tax assets and liabilities to be measured at the enacted tax rate expected to apply when temporary differences are to be realized or settled. Based on this, our liability in lieu of deferred income taxes w as re-measured at the date of enactment using the new tax rate.  We have completed the measurement and accounting for the effects of the TCJA. The re-measurement of our liability in lieu of deferred income taxes related to our non-regulated operations resulted in a $21 million charge to the nonoperating provision in lieu of tax expense for the year ended December 31, 2017. The re-measurement of our liability in lieu of deferred income taxes related to our regulated operations resulted in a $1.6 billion decrease in our liability in lieu of deferred income taxes at December 22, 2017 and a corresponding increase in our regulatory liabilities.  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,  2019 2018   Deferred Tax Related Assets:  Employee benefit liabilities $ 224 $ 234  Regulatory liabilities 51 55  Other 28 6  Total 303 295  Deferred Tax Related Liabilities:  Property, plant and equipment 1,851 1,651  Regulatory assets 272 245  Other 1 1  Total 2,124 1,897  Liability in lieu of deferred income taxes - net $ 1,821 $ 1,602  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,  2019 2018 2017   Reported in operating expenses:  Current:  U.S. federal $ 69 $ 112 $ (55)  State 22 21 20  Deferred:  U.S. federal 49 21 303  State - - -  Amortization of investment tax credits (2) (2) (2)  Total reported in operating expenses 138 152 266  Reported in other income and deductions:  Current:  U.S. federal (21) (32) (5)  State - - -  Deferred federal 6 (3) 6  Total reported in other income and deductions (15) (35) 1  Total provision in lieu of income taxes $ 123 $ 117 $ 267  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,  2019 2018 2017   Income before provision in lieu of income taxes $ 774 $ 662 $ 686  Provision in lieu of income taxes at the U.S. federal statutory rate of 21% for 2019 and 2018 and 35% for 2017 $ 163 $ 139 $ 240  Amortization of investment tax credits – net of deferred tax effect (2) (2) (2)  Amortization of excess deferred taxes (52) (18) (1)  Impact of federal statutory rate change from 35% to 21% - - 21  Texas margin tax, net of federal tax benefit 17 17 13  Nontaxable gains on benefit plan investments (2) (1) (4)  Other (1) (18) -  Reported provision in lieu of income taxes $ 123 $ 117 $ 267  Effective rate 15.9% 17.7% 38.9%  The net amounts of $1.821 billion and $1.602 billion reported in the balance sheets at December 31, 2019 and 2018, 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, 2009, however, the IRS has declined to review the tax returns for the years ended prior to January 1, 2016. Texas margin tax returns are under examination or still open for examination for tax years beginning after 2014. 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 2019 and 2018. In the first quarter 2017, EFH Corp. settled all open tax claims with the IRS. As a result, we reduced the liability for uncertain tax positions by $3 million. This reduction is reported as a decrease in income taxes in 2017. Noncurrent liabilities included no accrued interest related to uncertain tax positions at December 31, 2019 and 2018. There were no amounts recorded related to interest and penalties in the years ended December 31, 2019, 2018 and 2017. 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, 2019
Short-Term Borrowings [Abstract]
SHORT-TERM BORROWINGS	6. SHORT-TERM BORROWINGS  At December 31, 2019 and 2018, outstanding short-term borrowings under our CP Program and Credit Facility consisted of the following:   At December 31,  2019 2018  Total credit facility borrowing capacity $ 2,000 $ 2,000  Commercial paper outstanding (a) (46) (813)  Credit facility outstanding (b) - -  Letters of credit outstanding (c) (10) (9)  Available unused credit $ 1,944 $ 1,178 ____________ a) The weighted average interest rate for commercial paper was 1.84% and 2.74% at December 31, 2019 and December 31, 2018, respectively. b) At December 31, 2019, the applicable interest rate for any outstanding borrowings would have been LIBOR plus 1.00% . c) Interest rates on outstanding letters of credit at December 31, 2019 and December 31, 2018 were 1.2% based on our credit ratings.  CP Program  In March 2018, we established the CP Program, under which we may issue unsecured commercial paper notes (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 2017, 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. 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 has a five -year term expiring in November 2022 and 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 replaced our previous $2.0 billion secured revolving credit facility (previous credit facility), which was terminated in connection with our entrance into the Credit Facility. Borrowings under our previous credit facility were secured with the lien of the Deed of Trust discussed in Note 7 below.  Borrowings under the Credit Facility bear interest at per annum rates equal to, at our option, (i) adjusted LIBOR plus a spread ranging from 0 .875% to 1.50% 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 federal funds effective rate plus 0.50% , and (3) adjusted LIBOR plus 1.00% ) plus a spread ranging from 0.00% to 0.50% 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, 2019, letters of credit bore interest at 1.20% , and a commitment fee (at a rate of 0.125% 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.  May 2019 Short-Term Bridge Loan  On May 9, 2019, we entered into a short-term unsecured term loan credit agreement (Bridge Loan) in an aggregate principal amount of up to $600 million in connection with the InfraREIT Acquisition. The Bridge Loan had a six-month term. Borrowings under the Bridge Loan could only be used to finance the repayment of indebtedness of InfraREIT or its affiliates and to pay expenses and fees related to the InfraREIT Acquisition. A fee was payable to the lenders under the Bridge Loan in an amount equal to 0.075% per annum on the average daily undrawn amount of the commitments.  The Bridge Loan contained customary covenants for facilities of this type, restricting, subject to certain exceptions, us and our subsidiaries from, among other things, incurring additional liens, entering into mergers and consolidations, and sales of substantial assets. The Bridge Loan also contained a senior debt-to-capitalization ratio covenant that effectively limited our ability to incur indebtedness in the future.  On May 15, 2019, we borrowed $600 million under the Bridge Loan to pay, at closing of the InfraREIT Acquisition, all amounts outstanding under SDTS’s term loan, all amounts outstanding under the revolving credit facilities of SDTS and InfraREIT Partners, and amounts owed to discharge certain outstanding notes of InfraREIT’s subsidiaries. The borrowing under the Bridge Loan bore interest at a per annum rate equal to LIBOR plus 0.65% . The Bridge Loan was repaid in full in May 2019 with the proceeds from our May 23, 2019 senior secured notes issuance (discussed in Note 7 below) and as a result, the agreement is no longer in effect.  InfraREIT Short-Term Debt Repayments in Connection with the InfraREIT Acquisition In connection with the closing of the InfraREIT Acquisition, on May 16, 2019, the credit facilities of InfraREIT and its subsidiaries were terminated and borrowings totaling $114 million principal amount were repaid in full by Oncor. For more information on the extinguishment of InfraREIT debt in connection with the InfraREIT Acquisition, see Notes 2 and 7.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2019
Long-Term Debt [Abstract]
LONG-TERM DEBT	7. LONG-TERM DEBT  Our senior notes are 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, 2019 and 2018, our long-term debt consisted of the following:   December 31,  2019 2018   Fixed Rate Secured:  2.15% Senior Notes due June 1, 2019 $ - $ 250  5.75% Senior Notes due September 30, 2020 126 126  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 -  2.95% Senior Notes due April 1, 2025 350 350  3.86% Senior Notes, Series A, due December 3, 2025 174 -  3.86% Senior Notes, Series B, due January 14, 2026 38 -  3.70% Senior Notes due November 15, 2028 650 350  5.75% Senior Notes due March 15, 2029 318 318  7.25% Senior Notes, Series B, due December 30, 2029 36 -  6.47% Senior Notes, Series A, due September 30, 2030 83 -  7.00% Senior Notes due May 1, 2032 500 500  7.25% Senior Notes due January 15, 2033 350 350  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 500 500  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 -  3.10% Senior Notes, due September 15, 2049 700 -  Secured long-term debt 8,221 6,126  Variable Rate Unsecured:  Term loan credit agreement maturing December 9, 2019 - 350  Term loan credit agreement maturing October 6, 2020 460 -  Total long-term debt 8,681 6,476  Unamortized discount and debt issuance costs (56) (41)  Less amount due currently (608) (600)  Long-term debt, less amounts due currently $ 8,017 $ 5,835  Long-Term Debt-Related Activity in 2019  Debt Repayments  Repayments of long-term debt in 2019 consisted of $488 million aggregate principal amount of long-term debt of InfraREIT’s subsidiaries that we paid on May 16, 2019 in connection with and immediately following the InfraREIT Acquisition through repayment of $288 million principal amount of outstanding InfraREIT subsidiary senior notes (plus $5 million in accrued interest and $19 million in make-whole fees relating to those notes ) and repayment of an outstanding $200 million principal amount InfraREIT subsidiary term loan , $250 million aggregate principal amount of our 2.15 % senior secured notes due June 1, 2019, $350 million aggregate principal amount of the term loan credit agreement maturing on December 9, 2019 (which was repaid in full and extinguished in November 2019) and $6 million principal amount of the quarterly amortizing debt for senior secured notes issued under the Note Purchase Agreements .  Debt Issuances  Senior Secured Notes  In May 2019 we issued $500 million aggregate principal amount of 2.75% senior secured notes due 2024 (2024 Notes), $300 million aggregate principal amount of 3.70% senior secured notes due 2028 (2028 Notes) and $500 million aggregate principal amount of 3.80% Senior Secured Notes due 2049 (3.80% 2049 Notes). The 2028 Notes constitute an additional issuance of our 3.70% Senior Secured Notes due 2028, $350 million of which we previously issued on August 10, 2018 and are currently outstanding (Outstanding 2028 Notes). The 2028 Notes were issued as part of the same series as the Outstanding 2028 Notes. Additionally, the 2028 Notes exchanged or sold in connection with the transactions contemplated by a registration rights agreement are expected to become fungible with the Outstanding 2028 Notes. We used the proceeds (net of the initial purchasers’ discount, fees, expenses and accrued interest) of $1,297 million from the sale of the notes for general corporate purposes, including to repay all amounts outstanding under the Bridge Loan, to repay $250 million aggregate principal amount of our 2.15% Senior Secured Notes due June 1, 2019 and to repay CP Notes, when due, under our CP Program. For more information on the Bridge Loan, see Note 6. Prior to May 1, 2024, in the case of the 2024 Notes, August 15, 2028 in the case of the 2028 Notes and December 1, 2048, in the case of the 2049 Notes, Oncor 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 May 1, 2024, in the case of the 2024 Notes, August 15, 2028 in the case of the 2028 Notes and December 1, 2048, in the case of the 2049 Notes, Oncor 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.  On September 12, 2019, we issued $700 million aggregate principal amount of 3.10% senior secured notes due September 15, 2049 (3.10% 2049 Notes and, together with the 2024 Notes, 2028 Notes and the 3.80% 2049 Notes, the New Indenture Notes). We used the proceeds (net of the initial purchasers’ discount, fees and expenses) of $689 million from the sale of the 3.10% 2049 Notes for general corporate purposes, including to repay CP Notes, when due, under our CP Program.  Prior to March 15, 2049, Oncor may redeem the 3.10% 2049 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 March 15, 2049, Oncor may redeem the 3.10% 2049 Notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of the 3.10% 2049 Notes, plus accrued and unpaid interest.  The New Indenture Notes also contain customary events of default, including failure to pay principal or interest when due. The New Indenture Notes were issued in separate private placements . In November 2019, we completed an offering with the holders of the New Indenture Notes to exchange their respective New Indenture Notes for notes that have terms identical in all material respects to the New Indenture 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 October 2019.  Debt Exchange  In connection with closing the InfraREIT Acquisition on May 16, 2019, we exchanged $351 million principal amount of outstanding InfraREIT subsidiary senior notes for a like principal amount of newly issued Oncor secured senior notes. We received no proceeds from the issuance of the new Oncor notes and the exchanges were accounted for as debt modifications. Following are details of the exchanges:  (i) $87 million aggregate principal amount of newly issued Oncor 6.47% Senior Notes, Series A, due September 30, 2030 (2030 Notes), issued in exchange for a like principal amount of SDTS’s 6.47% Senior Notes due September 30, 2030, (ii) $38 million aggregate principal amount of newly issued Oncor 7.25% Senior Notes, Series B, due December 30, 2029 (2029 Notes), issued in exchange for a like principal amount of SDTS’s 7.25% Senior Notes due December 30, 2029, (iii) $14 million aggregate principal amount of newly issued Oncor 8.50% Senior Notes, Series C, due December 30, 2020 (2020 Notes), issued in exchange for a like principal amount of Transmission and Distributions Company, L.L.C.’s 8.5 0 % Senior Notes due December 30, 2020, (iv) $174 million aggregate principal amount of newly issued Oncor 3.86% Senior Notes, Series A, due December 3, 2025 (2025 Notes), issued in exchange for a like principal amount of SDTS’s 3.86% Senior Notes due December 3, 2025, and (v) $38 million aggregate principal amount of newly issued Oncor 3.86% Senior Notes, Series B, due January 14, 2026 (2026 Notes), issued in exchange for a like principal amount of SDTS’s 3.86% Senior Notes due January 14, 2026.  The 2030 N otes, 2029 Notes, 2020 Notes, 2025 Notes and 2026 Notes were each issued pursuant to a N ote P urchase A greement . Closing of the Note Purchase Agreements and issuance of the 2030 Notes, 2029 Notes, 2020 Notes, 2025 Notes and 2026 Notes (collectively, NPA Notes) occurred on May 16, 2019, immediately following consummation of the InfraREIT Acquisition.  The Note Purchase Agreements contain customary covenant restrictions and events of default. The NPA Notes are secured equally and ratably with our other secured indebtedness pursuant to the Deed of Trust. For more information on the Deed of Trust, see “Deed of Trust” below. We received no proceeds from the issuance of the NPA Notes.  Term Loan Credit Agreements  On September 6, 2019, we entered into an unsecured term loan credit agreement (2019 Term Loan Agreement) in an aggregate principal amount of up to $460 million. The 2019 Term Loan Agreement has a 13-month term, maturing on October 6, 2020. We borrowed the full aggregate principal amount available under the 2019 Term Loan Agreement of $460 million on September 25, 2019. The 2019 Term Loan Agreement bears interest at per annum rates equal to, at Oncor’s option, (i) LIBOR plus 0.50% , or (ii) an alternate base rate (the highest of (1) the prime rate of Wells Fargo Bank National Association, the administrative agent under the agreement , (2) the federal funds effective rate plus 0.50% , and (3) daily one-month LIBOR plus 1% ). We used the proceeds (net of fees and expenses) for general corporate purposes, including to repay CP Notes, when due, under our CP program.  The 2019 Term Loan Agreement contains customary covenants for facilities of this type, restricting, subject to certain exceptions, us and our subsidiaries from, among other things, incurring additional liens, entering into mergers and consolidations, and sales of substantial assets. The 2019 Term Loan Agreement contains a senior debt-to-capitalization ratio covenant that effectively limits our ability to incur indebtedness in the future. At December 31, 2019, we were in compliance with this covenant and all other covenants in the term loan credit agreement. See “Credit Rating Provisions, Covenants and Cross Default Provisions” below for additional information on this covenant and the calculation of this ratio.  In November 2019, we repaid $350 million, representing the full principal amount owed, under the term loan credit agreement entered into in 2018 that was scheduled to mature in December 2019. That term loan credit agreement contained covenants similar to the 2019 Term Loan Agreement. Upon repayment, th e 2018 term loan agreement ceased to be in effect.  Deed of Trust  Our secured indebtedness is secured equally and ratably by a first priority lien on property we acquired or constructed for the transmission and distribution of electricity. 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, 2019, the amount of available bond credits was $2,771 million 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 $2,410 million.  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, 2019, are as follows:   Year Amount  2020 $ 608  2021 9  2022 891  2023 10  2024 510  Thereafter 6,653  Unamortized discount and debt issuance costs (56)  Total $ 8,625  Fair Value of Long-Term Debt  At December 31, 2019 and 2018, the estimated fair value of our long-term debt (including current maturities) totaled $10.003 billion and $7.086 billion, respectively, and the carrying amount totaled $8.625 billion and $6.435 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, 2019
Commitments And Contingencies [Abstract]
COMMITMENTS AND CONTINGENCIES	8. 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, 2019 .     At December 31,  2019  Operating Leases:  ROU assets:  Operating lease ROU and other assets $ 92   Lease liabilities:  Operating lease and other current liabilities $ 26  Employee benefit, operating lease and other obligations 66  Total operating lease liabilities $ 92   Weighted-average remaining lease term (in years) 4  Weighted-average discount rate 3.3%   The components of lease costs and cash paid for amounts included in the measurement of lease liabilities in 2019 were as follows:    Year Ended  December 31, 2019  Operating lease cost:  Operating lease costs (including amounts allocated to property, plant and equipment) $ 40  Short-term lease costs 34  Total operating lease costs $ 74   Operating lease payments:  Cash paid for amounts included in the measurement of lease liabilities $ 32  The table below presents the maturity analysis of our lease liabilities and reconciliation to the present value of lease liabilities:      Year Amount  2020 $ 28  2021 25  2022 19  2023 13  2024 8  Thereafter 3  Total undiscounted lease payments 96  Less imputed interest (4)  Total operating lease obligations $ 92   Leases that Have Not Yet Commenced  In December 2019, we entered into a 15 year lease agreement for replacement office space. The lease will commence in February 2020 and is expected to be accounted for as an operating lease.  Leases Disclosures Under Previous GAAP  At December 31, 2018, our future minimum lease payments under our operating leases (with initial or remaining noncancelable lease terms in excess of one year) were as follows:   Year Amount  2019 $ 29  2020 22  2021 20  2022 15  2023 8  Thereafter 5  Total future minimum lease payments $ 99  Rent charged to operation and maintenance expense totaled $28 million and $27 million for the years ended December 31, 2018 and 2017, respectively.  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.  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 2020 is $50 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, 2019, approximately 18% of our full time employees were represented by a labor union and covered by a collective bargaining agreement with an expiration date of October 25, 2022 .  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, 2019
Membership Interests [Abstract]
MEMBERSHIP INTERESTS	9. MEMBERSHIP INTERESTS  Cash Contributions   On February 18, 2020, we received cash capital contributions from our members totaling $87 million. During 2019, we received the following capital cash contributions from our members.     Received Amount  November 21, 2019 $ 340  October 28, 2019 98  July 29, 2019 70  May 15, 2019 1,330  April 30, 2019 70  February 19, 2019 70  $ 1,978  Cash Distributions  Distributions are limited by the requirement to maintain our regulatory capital structure at or below the assumed 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 the effects of acquisition accounting from a 2007 transaction (which included recording the initial goodwill and fair value adjustments and subsequent related impairments and amortization).  The PUCT order issued in the Sempra Acquisition and our Limited Liability Company Agreement 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 be out of compliance with the PUCT’s approved debt-to-equity ratio, which is currently 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, 2019, we had $751 million available to distribute to our members as our regulatory capitalization ratio was 54.8% debt to 45.2% equity.  On February 19, 2020, our board of directors declared a cash distribution of $91 million, which was paid to our members on February 20, 2020. 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  During 2018, our board of directors declared, and we paid, the following cash distributions to our members:     Declaration Date Payment Date Amount  October 24, 2018 November 6, 2018 $ 179  July 25, 2018 August 1, 2018 30  $ 209   Accumulated Other Comprehensive Income (Loss) (AOCI)  The following table presents the changes to accumulated other comprehensive income (loss) for the years ended December 31, 2019, 2018 and 2017 net of tax.     Cash Flow Hedges – Interest Rate Swap Defined Benefit Pension and OPEB Plans Accumulated Other Comprehensive Income (Loss)   Balance at December 31, 2016 $ (20) $ (91) $ (111)  Defined benefit pension plans - 8 8  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges 2 - 2  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 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 2 - 2  Amounts reclassified from accumulated other comprehensive income (loss) to capital account (4) - (4)  Balance at December 31, 2019 $ (18) $ (121) $ (139) 

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
Employee Benefit Plans [Abstract]
EMPLOYEE BENEFIT PLANS	10. 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, 2019 and 2018, we had recorded regulatory assets totaling $964 million and $ 1,018 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 under the Vistra Retirement Plan (formerly EFH 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. 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, 2019, the pension plans’ projected benefit obligation included a net actuarial loss of $367 million for 2019 due primarily to a decrease in the discount rate. Actual returns on the plans’ assets in 2019 were more than the expected return on assets by $367 million. We expect the pension plans’ amortizations of net actuarial losses to be $47 million in 2020.  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, 2019, the Oncor OPEB Plans’ projected benefit obligation included a net actuarial gain of $5 million for 2019, including $145 million gain associated with mortality assumption changes, and updates to health care claims and trend assumptions, offset by a loss of $126 million due to a decrease in the discount rate and a loss of $14 million associated with census date updates. Actual returns on Oncor OPEB Plans’ assets in 2019 were more than the expected return on assets by $17 million resulting in a net actuarial gain of $22 million. We expect the Oncor OPEB Plans’ amortizations of net actuarial losses to decrease by $9 million in 2020 reflecting these changes.  Pension and OPEB Costs Recognized as Expense  Pension and OPEB amounts provided herein include amounts related only to our portion of 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,  2019 2018 2017   Pension costs $ 63 $ 77 $ 85  OPEB costs 41 70 58  Total benefit costs 104 147 143  Less amounts recognized principally as property or a regulatory asset (27) (69) (98)  Net amounts recognized as operation and maintenance expense or other deductions $ 77 $ 78 $ 45  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, 2019, 2018 and 2017 measurement dates:     Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2017 2019 2018 2017   Assumptions Used to Determine Net Periodic Pension and OPEB Costs:  Discount rate 4.18% 3.54% 4.05% 4.41% 3.73% 4.35%  Expected return on plan assets 5.42% 5.11% 5.17% 6.19% 6.20% 6.10%  Rate of compensation increase 4.53% 4.46% 3.33% - - -   Components of Net Pension and OPEB Costs:  Service cost $ 25 $ 27 $ 24 $ 6 $ 8 $ 7  Interest cost 128 121 131 43 44 47  Expected return on assets (119) (120) (115) (7) (9) (8)  Amortization of prior service cost (credit) - - - (20) (30) (20)  Amortization of net loss 29 49 45 19 57 32  Net periodic pension and OPEB costs $ 63 $ 77 $ 85 $ 41 $ 70 $ 58   Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:  Net loss (gain) $ - $ 67 $ (11) $ (22) $ (177) $ 139  Amortization of net loss (29) (49) (45) (19) (57) (32)  Plan amendments - - - - - (78)  Amortization of prior service (cost) credit - - - 20 30 20  Total recognized as regulatory assets or other comprehensive income (29) 18 (56) (21) (204) 49  Total recognized in net periodic pension and OPEB costs and as regulatory assets or other comprehensive income $ 34 $ 95 $ 29 $ 20 $ (134) $ 107      Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2017 2019 2018 2017   Assumptions Used to Determine Benefit Obligations at Period End:  Discount rate 3.13% 4.18% 3.54% 3.29% 4.41% 3.73%  Rate of compensation increase 4.64% 4.53% 4.46% - - -     Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2019 2018   Change in Projected Benefit Obligation:  Projected benefit obligation at beginning of year $ 3,162 $ 3,500 $ 1,006 $ 1,198  Service cost 25 27 6 8  Interest cost 128 121 43 44  Participant contributions - - 19 19  Plan amendments - - - -  Actuarial (gain) loss 367 (232) (5) (196)  Benefits paid (164) (175) (70) (67)  Annuity purchase (118) (79) - -  Projected benefit obligation at end of year $ 3,400 $ 3,162 $ 999 $ 1,006  Accumulated benefit obligation at end of year $ 3,283 $ 3,069 $ - $ -   Change in Plan Assets:  Fair value of assets at beginning of year $ 2,249 $ 2,600 $ 132 $ 149  Actual return (loss) on assets 486 (179) 25 (10)  Employer contributions 41 82 35 41  Participant contributions - - 19 19  Benefits paid (164) (175) (70) (67)  Annuity purchase (118) (79) - -  Fair value of assets at end of year $ 2,494 $ 2,249 $ 141 $ 132   Funded Status:  Projected benefit obligation at end of year $ (3,400) $ (3,162) $ (999) $ (1,006)  Fair value of assets at end of year 2,494 2,249 141 132  Funded status at end of year $ (906) $ (913) $ (858) $ (874)    Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2019 2018   Amounts Recognized in the Balance Sheet Consist of:  Liabilities:  Other current liabilities $ (5) $ (4) $ (15) $ (7)  Other noncurrent liabilities (901) (909) (843) (867)  Net liability recognized $ (906) $ (913) $ (858) $ (874)  Regulatory assets:  Net loss $ 531 $ 534 $ 129 $ 171  Prior service cost (credit) - - (37) (57)  Net regulatory asset recognized $ 531 $ 534 $ 92 $ 114  Accumulated other comprehensive net loss $ 120 $ 147 $ 1 $ 1  The following tables provide information regarding the assumed health care cost trend rates.   Year Ended December 31,  2019 2018   Assumed Health Care Cost Trend Rates – Not Medicare Eligible:  Health care cost trend rate assumed for next year 7.20% 7.60%  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 2026   Assumed Health Care Cost Trend Rates – Medicare Eligible:  Health care cost trend rate assumed for next year 8.00% 8.70%  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 2027   1-Percentage Point Increase 1-Percentage Point Decrease   Sensitivity Analysis of Assumed Health Care Cost Trend Rates:  Effect on accumulated postretirement obligation $ 128 $ (106)  Effect on postretirement benefits cost 5 (4)  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,  2019 2018   Pension Plans with PBO and ABO in Excess of Plan Assets:  Projected benefit obligations $ 3,400 $ 3,162  Accumulated benefit obligations 3,283 3,069  Plan assets 2,494 2,249  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 27% of total investments at December 31, 2019.  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, 2019 provided below are consistent with the asset allocation targets.  Fair Value Measurement of Pension Plans’ Assets  At December 31, 2019 and 2018, pension plans’ assets measured at fair value on a recurring basis consisted of the following:   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   At December 31, 2018  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 170 $ 2 $ - $ 172  International 239 - - 239  Fixed income securities:  Corporate bonds (a) - 930 - 930  U.S. Treasuries - 110 - 110  Other (b) - 69 - 69  Real estate - - 3 3  Total assets in the fair value hierarchy $ 409 $ 1,111 $ 3 1,523  Total assets measured at net asset value (c) 726  Total fair value of plan assets $ 2,249 _____________ (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, 2019 and 2018, the Oncor OPEB Plans’ assets measured at fair value on a recurring basis consisted of the following:   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   At December 31, 2018  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 15 $ - $ - $ 15  Equity securities:  U.S. 21 - - 21  International 22 - - 22  Fixed income securities:  Corporate bonds (a) - 26 - 26  U.S. Treasuries - 3 - 3  Other (b) 28 1 - 29  Total assets in the fair value hierarchy $ 86 $ 30 $ - 116  Total assets measured at net asset value (c) 16  Total fair value of plan assets $ 132 _____________ (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 7.63% 401(h) accounts 6.26%  U.S. equity securities 6.80% Life insurance VEBA 6.04%  Real estate 5.20% Union VEBA 6.04%  Credit strategies 4.56% Non-union VEBA 1.80%  Fixed income securities 3.40% Shared retiree VEBA 1.80%  Weighted average (a) 5.22% Weighted average 5.90% _____________ (a) The 2020 expected long-term rate of return for the nonregulated portion of the Oncor Retirement Plan is 4.18%, and for Oncor’s portion of the Vistra Retirement Plan is 4.89% .  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, 2019, 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, 2019 consisted of 927 corporate bonds with an average rating of AA and AAA using Moody’s, S&P and Fitch ratings. For Oncor’s portion of the Vistra Retirement Plan and the Oncor OPEB Plans at December 31, 2019, 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, 2019 consisted of 361 corporate bonds with an average rating of AA using Moody’s, S&P and Fitch ratings.  Amortization in 2020  In 2020, amortization of the net actuarial loss for the defined benefit pension plans from regulatory assets and other comprehensive income into net periodic benefit cost is expected to be $43 million and $5 million, respectively. No amortization of prior service credit is expected in 2020 for the defined benefit pension plans. Amortization of the net actuarial loss for the OPEB plans from regulatory assets and other comprehensive income into net periodic benefit cost is expected to be $10 million and zero , respectively. Amortization of prior service credit for the OPEB plans from regulatory assets and other comprehensive income into net periodic benefit cost is expected to be $20 million and zero , respectively.  Pension and Oncor OPEB Plans Cash Contributions  Our contributions to the benefit plans were as follows:   Year Ended December 31,  2019 2018 2017   Pension plans contributions $ 41 $ 82 $ 149  Oncor OPEB Plans contributions 35 41 31  Total contributions $ 76 $ 123 $ 180  Our funding for the pension plans and the Oncor OPEB Plans is expected to total $177 million and $35 million, respectively in 2020 and approximately $571 million and $176 million, respectively, in the five year period 2020 to 2024.  Future Benefit Payments  Estimated future benefit payments to participants are as follows:   2020 2021 2022 2023 2024 2025-29   Pension plans $ 179 $ 183 $ 188 $ 191 $ 196 $ 996  Oncor OPEB Plans $ 50 $ 51 $ 53 $ 55 $ 56 $ 285  Thrift Plan  Our employees are eligible to participate in a qualified savings plan, a participant-directed defined contribution plan intended to qualify under Section 401(a) of the Code, and is subject to the provisions of ERISA. 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 $20 million, $19 million and $17 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2019
Stock-Based Compensation [Abstract]
STOCK-BASED COMPENSATION	11. 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 2012, 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 and $1 million in accretion and interest with respect to such dividend and interest accounts in years 2018 and 2017, respectively. No SARs liability remained at December 31, 2019. 

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2019
Related-Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	12. 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 (as successor to EFH Corp.), 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, 2019 At December 31, 2018  STH Texas Transmission Total STH Texas Transmission Total   Federal income taxes payable (receivable) $ (2) $ (1) $ (3) $ 4 $ 1 $ 5  Texas margin taxes payable 22 - 22 21 - 21  Net payable (receivable) $ 20 $ (1) $ 19 $ 25 $ 1 $ 26  Cash payments made to (received from) members related to income taxes consisted of the following:   Year Ended December 31, 2019 Year Ended December 31, 2018 Year Ended December 31, 2017  STH Texas Transm. Total STH EFH Corp. Texas Transm. Total EFH Corp. Texas Transm. Total   Federal income taxes $ 45 $ 11 $ 56 $ 59 $ (19) $ 10 $ 50 $ (102) $ (12) $ (114)  Texas margin taxes 22 - 22 21 - - 21 20 - 20  Total payments (receipts) $ 67 $ 11 $ 78 $ 80 $ (19) $ 10 $ 71 $ (82) $ (12) $ (94)  · 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 and 2017, 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 dollars 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. Cash payments were made for such services to this vendor and/or its subsidiaries totaling $219 million for 2017, of which approximately $210 million was capitalized and $9 million recorded as an operation and maintenance expense.  · From the May 16, 2019 InfraREIT Acquisition date through December 31, 2019, we paid Sharyland $9 million pursuant to certain of their transmission and distribution tariffs applicable to us and we provided Sharyland with substation monitoring and switching service of $303,000 .  · For the year ended December 31, 2019, we paid Sempra $109,000 pursuant to an agreement for certain corporate support services, including tax work.  See Notes 1, 5, and 9 for information regarding the tax sharing agreement and distributions to members.

Supplementary Financial Informa

Supplementary Financial Information	12 Months Ended
	Dec. 31, 2019
Supplementary Financial Information [Abstract]
SUPPLEMENTARY FINANCIAL INFORMATION	13. SUPPLEMENTARY FINANCIAL INFORMATION  Other Deductions and (Income)      Year Ended December 31,  2019 2018 2017   Professional fees $ 10 $ 12 $ 15  Sempra Acquisition related costs - 12 -  InfraREIT Acquisition related costs 9 - -  Recoverable Pension and OPEB - non-service costs 57 53 31  Non-recoverable pension and OPEB (Note 10) 4 6 5  AFUDC equity income (10) - -  Interest income (5) (1) (6)  Other (2) 2 1  Total other deductions and (income) - net $ 63 $ 84 $ 46  Interest Expense and Related Charges   Year Ended December 31,  2019 2018 2017   Interest $ 382 $ 358 $ 351  Amortization of debt issuance costs and discounts 9 6 3  Less AFUDC – capitalized interest portion (16) (13) (12)  Total interest expense and related charges $ 375 $ 351 $ 342  Trade Accounts and Other Receivables  Trade accounts and other receivables reported on our balance sheet consisted of the following:   At December 31,  2019 2018   Gross trade accounts and other receivables $ 666 $ 562  Allowance for uncollectible accounts (5) (3)  Trade accounts receivable – net $ 661 $ 559  At December 31, 2019, REP subsidiaries of two of our largest counterparties represented 15% and 11% of the trade accounts receivable balance and at December 31, 2018, represented 13% and 10% 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,  2019 2018   Assets related to employee benefit plans $ 119 $ 108  Land 12 12  Other 2 -  Total investments and other property $ 133 $ 120  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, 2019 and 2018, the face amount of these policies totaled $172 million and $157 million, respectively, and the net cash surrender values (determined using a Level 2 valuation technique) totaled $95 million and $87 million at December 31, 2019 and 2018, 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, 2019 2019 2018  Assets in service:  Distribution 2.8% / 35.8 years $ 14,007 $ 13,105  Transmission 2.9% / 35.0 years 11,094 8,568  Other assets 6.9% / 14.5 years 1,648 1,497  Total 26,749 23,170  Less accumulated depreciation 7,986 7,513  Net of accumulated depreciation 18,763 15,657  Construction work in progress 585 417  Held for future use 22 16  Property, plant and equipment – net $ 19,370 $ 16,090  Depreciation expense as a percent of average depreciable property approximated 2.7% , 2.8% and 3.4% for the years ended December 31, 2019, 2018 and 2017, 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, 2019 At December 31, 2018  Gross Gross  Carrying Accumulated Carrying Accumulated  Amount Amortization Net Amount Amortization Net  Identifiable intangible assets subject to amortization:  Land easements $ 575 $ 107 $ 468 $ 464 $ 101 $ 363  Capitalized software 933 430 503 787 385 402  Total $ 1,508 $ 537 $ 971 $ 1,251 $ 486 $ 765  A ggregate amortization expense for intangible assets totaled $52 million, $50 million and $57 million for the years ended December 31, 2019, 2018 and 2017, respectively. At December 31, 2019, the weighted average remaining useful lives of capitalized land easements and software were 83 years and 9 years, respectively. The estimated aggregate amortization expense for each of the next five fiscal years is as follows:   Year Amortization Expense   2020 $ 61  2021 61  2022 61  2023 61  2024 60  Goodwill totaling $ 4,740 million and $4,064 million were reported on our balance sheet at December 31, 2019 and 2018, respectively. The increase is due to the InfraREIT Acquisition. None of this goodwill is being deducted for tax purposes. See Note 1 regarding goodwill impairment assessment and testing.  Employee Benefit, Operating Lease and Other Obligations  Employee benefit, operating lease and other obligations reported on our balance sheet consisted of the following:    At December 31,  2019 2018   Retirement plans and other employee benefits $ 1,834 $ 1,858  Operating lease liabilities (Notes 1 and 8) 66 -  Investment tax credits 6 8  Other 74 77  Total employee benefit, operating lease and other obligations $ 1,980 $ 1,943  Supplemental Cash Flow Information   Year Ended December 31,  2019 2018 2017  Cash payments related to:   Interest $ 368 $ 368 $ 345  Less capitalized interest (16) (13) (12)  Interest payments (net of amounts capitalized) $ 352 $ 355 $ 333   Amount in lieu of income taxes (a):  Federal $ 56 $ 50 $ (114)  State 22 21 20  Total payments (refunds) in lieu of income taxes $ 78 $ 71 $ (94)   Noncash increase in operating lease obligation for ROU assets $ 38 $ - $ -   Noncash Sharyland 2017 Asset Exchange costs $ - $ - $ 383   Noncash investing and financing activity (b):  Acquisition:  Assets acquired $ 2,547 $ - $ -  Liabilities assumed (1,223) - -  Cash paid $ 1,324 $ - $ -   Noncash construction expenditures (c) $ 278 $ 174 $ 129 ______________ (a) See Note 12 for income tax related detail. (b) See Note 7 for more information on noncash debt exchanges related to InfraREIT Acquisition. (c) Represents end-of-period accruals.  Quarterly Information (unaudited)  Results of operations by quarter for the years ended December 31, 2019 and 2018 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.   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   2018 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 990 $ 1,021 $ 1,095 $ 995  Operating income 202 244 293 206  Net income 89 143 194 119 

EFH Bankruptcy Proceedings And

EFH Bankruptcy Proceedings And Sempra Acquisition	12 Months Ended
	Dec. 31, 2019
EFH Bankruptcy Proceedings And Sempra Acquisition [Abstract]
EFH BANKRUPTCY PROCEEDINGS AND SEMPRA ACQUISITION	 14. EFH BANKRUPTCY PROCEEDINGS AND SEMPRA ACQUISITION  In April 2014, EFH Corp. and the substantial majority of its direct and indirect subsidiaries at the time commenced proceedings under Chapter 11 of the U.S. Bankruptcy Code. The Oncor Ring-Fenced Entities were not parties to the EFH Bankruptcy Proceedings. On March 9, 2018, Sempra acquired the 80.03% of Oncor’s membership interests owned indirectly by EFH Corp. and EFIH (Sempra Acquisition). As a result of the Sempra Acquisition, EFH Corp. merged with an indirect subsidiary of Sempra, with EFH Corp. (renamed STH) continuing as the surviving company and an indirect, wholly owned subsidiary of Sempra. Sempra paid cash consideration of approximately $9.45 billion to acquire the indirect 80.03% outstanding membership interest in Oncor held by Oncor Holdings and other EFH Corp. assets and liabilities unrelated to Oncor. In addition, in a separate transaction, Oncor Holdings acquired 0.22% of the outstanding membership interests in Oncor from Investment LLC for $26 million in cash, which represents approximately $18.60 per membership interest. As a result, after the Sempra Acquisition, Oncor Holdings owns 80.25% of our outstanding membership interests and Texas Transmission owns 19.75% of our outstanding membership interests. In February 20 20 , Sempra acquired (through STIH) an indirect 1% ownership interest in Texas Transmission.  The Sempra Acquisition was consummated after obtaining the approval of the bankruptcy court in the EFH Bankruptcy Proceedings, the Federal Communications Commission and the PUCT. The PUCT approval was obtained in Docket No. 47675, and the final order issued in that docket as well as our Limited Liability Company Agreement outline 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. These limitations include limited representation on the board of directors of Oncor. For more information on the ring-fencing measures applicable after the Sempra Acquisition, see Note 1.  The Sempra Order also contains certain operational and financial commitments, including that Oncor will make minimum capital expenditures equal to at least $7.5 billion over the period from January 1, 2018 until December 31, 2022 (subject to certain adjustments).

Description Of Business And S_2

Description Of Business And Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
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 for the fiscal year ended December 31, 2019, include the results of our wholly owned indirect subsidiary, NTU, which is a regulated utility that provides electricity transmission delivery service in the north-central, western and panhandle regions of Texas. We acquired NTU as part of the InfraREIT Acquisition that closed on May 16, 2019. 
Ring-Fencing Measures	Ring-Fencing Measures  Since 200 7 , 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 2008 sale of 19.75% of Oncor’s equity interests to Texas Transmission.  In March 2018, 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.  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 the officer being employed by Oncor. 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 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 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 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 stock 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 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 stock 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.
Goodwill	Goodwill  The increase in goodwill to $4,740 million at December 31, 2019 from $4,064 million at December 31, 2018 is due to the InfraREIT Acquisition. See Note 2 for more information on the InfraREIT Acquisition.
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 4 for additional information regarding revenues.
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.  If at the assessment date our carrying value exceeds our estimated fair value (enterprise value), then the estimated enterprise value is compared to the estimated fair values of our operating assets (including identifiable intangible assets) and liabilities at the assessment date. The resultant implied goodwill amount is compared to the recorded goodwill amount. Any excess of the recorded goodwill amount over the implied goodwill amount is written off as an impairment charge.  In each of 2019, 2018 and 2017, 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 additional testing for impairment was required and n o impairments were recognized .
Provision In Lieu Of Income Taxes	Provision in Lieu of Income Taxes  Our tax sharing agreement with Oncor Holdings, Texas Transmission and STH (as successor to EFH Corp.) 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 5.
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 10 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 and prudence and possible disallowance. 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 3 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 13 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, temporary cash investments purchased with an original maturity of three months or less 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 10) and long-term debt (see Note 7).  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. 
Changes In Accounting Standards	Changes in Accounting Standards  Topic 842, “Leases” – In February 2016, the FASB issued ASU 2016-02 which created FASB Topic 842, Leases (Topic 842). Topic 842 amends previous GAAP to require the balance sheet recognition of substantially all lease assets and liabilities, including operating leases. Operating lease liabilities are not classified as debt for GAAP purposes under Topic 842 and are not treated as debt for our regulatory purposes. All of Oncor’s existing leases meet the definition of an operating lease. Under the new rules, the recognition of any finance leases (previously known as capital leases) on the balance sheet are classified as debt for both GAAP and regulatory capital structure purposes (see Note 8 for details) similar to the previous capital lease treatment.  We adopted Topic 842 on January 1, 2019, using the optional transition method to apply the new guidance prospectively and not restate comparative periods. We elected the package of practical expedients that permits us to not reassess (a) whether a contract is or contains a lease, (b) lease classification or (c) determination of initial direct costs, which allows us to carry forward accounting conclusions under previous GAAP on contracts that commenced prior to adoption of the lease standard. We also elected the land easement practical expedient, which allows us to continue to account for pre-existing land easements under our accounting policy that existed before adoption of the lease standard. We did not elect the practical expedient to use hindsight in making judgments when determining the lease term.  The adoption of Topic 842 affects our balance sheet, as our contracts for office space, service centers and fleet vehicles are operating leases. The following table shows the increases on our balance sheet at January 1, 2019 from the initial adoption of Topic 842.     At January 1, 2019  Operating Leases:  ROU assets:  Operating lease ROU and other assets $ 82   Lease liabilities:  Operating lease and other current liabilities $ 26  Employee benefit, operating lease and other obligations 56  Total operating lease liabilities $ 82  Topic 220, “Income Statement—Reporting Comprehensive Income” amended by ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” – In February 2018, the FASB issued ASU 2018-02, an amendment to Topic 220. Under ASU 2018-02, an entity is required to provide certain disclosures regarding stranded tax effects, including its accounting policy related to releasing the income tax effects from accumulated other comprehensive income (AOCI). We elected to reclassify stranded tax effects resulting from the TCJA from AOCI to capital accounts. Our stranded tax effects in AOCI, which are related to previous interest rate cash flow hedges, were $4 million and increased our capital account upon reclassification. We adopted the standard on a prospective basis effective January 1, 2019.  Topic 326, “Financial Instruments—Credit Losses” – In June 2016 the FASB issued ASU No. 2016-13, which changes how entities account for credit losses on receivables and certain other 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. Topic 326 is required to be adopted in the first quarter of fiscal 2020 with earlier adoption permitted. We adopted on a prospective basis effective January 1, 2020. The adoption of the new standard did not have a material impact on our consolidated financial statements.  Topic 350, “Intangibles, Goodwill and Other —Internal-Use Software (Subtopic 40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service ” – In August 2018, the FASB issued ASU 2018-15 which clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is required to be adopted in the first quarter of fiscal 2020 with earlier adoption permitted. We have early adopted on a prospective basis effective July 1, 2019. The early adoption did not have a material effect on our consolidated financial statements.

Description Of Business And S_3

Description Of Business And Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Description Of Business And Significant Accounting Policies [Abstract]
Schedule Of Adoption Of Topic 842	  At January 1, 2019  Operating Leases:  ROU assets:  Operating lease ROU and other assets $ 82   Lease liabilities:  Operating lease and other current liabilities $ 26  Employee benefit, operating lease and other obligations 56  Total operating lease liabilities $ 82 

Acquisition Activity (Tables)

Acquisition Activity (Tables)	12 Months Ended
	Dec. 31, 2019
Acquisition Activity [Abstract]
Total Purchase Price Paid	  Purchase of outstanding InfraREIT shares and units $ 1,275  Certain transaction costs of InfraREIT paid by Oncor (a) 49  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 

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2019
Regulatory Matters [Abstract]
Components Of Regulatory Assets And Liabilities	  Remaining Rate Recovery/Amortization Period at At December 31,  December 31, 2019 2019 2018   Regulatory assets:  Employee retirement liability (a)(b)(c) To be determined $ 623 $ 648  Employee retirement costs being amortized 8 years 262 297  Employee retirement costs incurred since the last rate review period (b) To be determined 79 73  Self-insurance reserve (primarily storm recovery costs) being amortized 8 years 309 351  Self-insurance reserve incurred since the last rate review period (primarily storm related) (b) To be determined 238 59  Securities reacquisition costs Lives of related debt 29 10  Deferred conventional meter and metering facilities depreciation 1 year 15 36  Under-recovered AMS costs 8 years 170 185  Energy efficiency performance bonus (a) 1 year or less 9 7  Wholesale distribution substation service To be determined 34 15  Other regulatory assets Various 7 10  Total regulatory assets 1,775 1,691   Regulatory liabilities:  Estimated net removal costs Lives of related assets 1,178 1,023  Excess deferred taxes Primarily over lives of related assets 1,574 1,571  Over-recovered wholesale transmission service expense (a) 1 year or less 30 89  Other regulatory liabilities Various 11 14  Total regulatory liabilities 2,793 2,697  Net regulatory assets (liabilities) $ (1,018) $ (1,006) ____________ (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. 

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2019
Revenues [Abstract]
Disaggregation Of Revenues	  Year Ended December 31,  2019 2018  Operating revenues  Revenues contributing to earnings:  Distribution base revenues $ 2,143 $ 2,139  Transmission base revenues (TCOS revenues)  Billed to third-party wholesale customers 681 548  Billed to REPs serving Oncor distribution customers, through TCRF 391 310  Total transmission base revenues 1,072 858  Other miscellaneous revenues 77 71  Total revenues contributing to earnings 3,292 3,068   Revenues collected for pass-through expenses:  TCRF - third-party wholesale transmission service 1,005 962  EECRF and other regulatory charges 50 71  Revenues collected for pass-through expenses 1,055 1,033   Total operating revenues $ 4,347 $ 4,101 

Provision In Lieu Of Income T_2

Provision In Lieu Of Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Provision In Lieu Of Income Taxes [Abstract]
Schedule Of Deferred Tax Assets and Liabilities	  At December 31,  2019 2018   Deferred Tax Related Assets:  Employee benefit liabilities $ 224 $ 234  Regulatory liabilities 51 55  Other 28 6  Total 303 295  Deferred Tax Related Liabilities:  Property, plant and equipment 1,851 1,651  Regulatory assets 272 245  Other 1 1  Total 2,124 1,897  Liability in lieu of deferred income taxes - net $ 1,821 $ 1,602 
Components Of Income Tax Provisions (Benefits)	  Year Ended December 31,  2019 2018 2017   Reported in operating expenses:  Current:  U.S. federal $ 69 $ 112 $ (55)  State 22 21 20  Deferred:  U.S. federal 49 21 303  State - - -  Amortization of investment tax credits (2) (2) (2)  Total reported in operating expenses 138 152 266  Reported in other income and deductions:  Current:  U.S. federal (21) (32) (5)  State - - -  Deferred federal 6 (3) 6  Total reported in other income and deductions (15) (35) 1  Total provision in lieu of income taxes $ 123 $ 117 $ 267 
Schedule Of Income Tax Reconciliation	  Year Ended December 31,  2019 2018 2017   Income before provision in lieu of income taxes $ 774 $ 662 $ 686  Provision in lieu of income taxes at the U.S. federal statutory rate of 21% for 2019 and 2018 and 35% for 2017 $ 163 $ 139 $ 240  Amortization of investment tax credits – net of deferred tax effect (2) (2) (2)  Amortization of excess deferred taxes (52) (18) (1)  Impact of federal statutory rate change from 35% to 21% - - 21  Texas margin tax, net of federal tax benefit 17 17 13  Nontaxable gains on benefit plan investments (2) (1) (4)  Other (1) (18) -  Reported provision in lieu of income taxes $ 123 $ 117 $ 267  Effective rate 15.9% 17.7% 38.9% 

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2019
Short-Term Borrowings [Abstract]
Schedule Of Short-Term Borrowings	  At December 31,  2019 2018  Total credit facility borrowing capacity $ 2,000 $ 2,000  Commercial paper outstanding (a) (46) (813)  Credit facility outstanding (b) - -  Letters of credit outstanding (c) (10) (9)  Available unused credit $ 1,944 $ 1,178 ____________ a) The weighted average interest rate for commercial paper was 1.84% and 2.74% at December 31, 2019 and December 31, 2018, respectively. b) At December 31, 2019, the applicable interest rate for any outstanding borrowings would have been LIBOR plus 1.00% . c) Interest rates on outstanding letters of credit at December 31, 2019 and December 31, 2018 were 1.2% based on our credit ratings.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Long-Term Debt [Abstract]
Schedule Of Long-Term Debt	  December 31,  2019 2018   Fixed Rate Secured:  2.15% Senior Notes due June 1, 2019 $ - $ 250  5.75% Senior Notes due September 30, 2020 126 126  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 -  2.95% Senior Notes due April 1, 2025 350 350  3.86% Senior Notes, Series A, due December 3, 2025 174 -  3.86% Senior Notes, Series B, due January 14, 2026 38 -  3.70% Senior Notes due November 15, 2028 650 350  5.75% Senior Notes due March 15, 2029 318 318  7.25% Senior Notes, Series B, due December 30, 2029 36 -  6.47% Senior Notes, Series A, due September 30, 2030 83 -  7.00% Senior Notes due May 1, 2032 500 500  7.25% Senior Notes due January 15, 2033 350 350  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 500 500  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 -  3.10% Senior Notes, due September 15, 2049 700 -  Secured long-term debt 8,221 6,126  Variable Rate Unsecured:  Term loan credit agreement maturing December 9, 2019 - 350  Term loan credit agreement maturing October 6, 2020 460 -  Total long-term debt 8,681 6,476  Unamortized discount and debt issuance costs (56) (41)  Less amount due currently (608) (600)  Long-term debt, less amounts due currently $ 8,017 $ 5,835 
Schedule Of Long-Term Debt Maturity	  Year Amount  2020 $ 608  2021 9  2022 891  2023 10  2024 510  Thereafter 6,653  Unamortized discount and debt issuance costs (56)  Total $ 8,625 

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies [Abstract]
Schedule Of Lease Information	  At December 31,  2019  Operating Leases:  ROU assets:  Operating lease ROU and other assets $ 92   Lease liabilities:  Operating lease and other current liabilities $ 26  Employee benefit, operating lease and other obligations 66  Total operating lease liabilities $ 92   Weighted-average remaining lease term (in years) 4  Weighted-average discount rate 3.3% 
Schedule Of Lease Costs	  Year Ended  December 31, 2019  Operating lease cost:  Operating lease costs (including amounts allocated to property, plant and equipment) $ 40  Short-term lease costs 34  Total operating lease costs $ 74   Operating lease payments:  Cash paid for amounts included in the measurement of lease liabilities $ 32  
Schedule Of Operating Lease Maturity	  Year Amount  2020 $ 28  2021 25  2022 19  2023 13  2024 8  Thereafter 3  Total undiscounted lease payments 96  Less imputed interest (4)  Total operating lease obligations $ 92 
Schedule Of Future Miinimum Lease Payments Under Operating Leases	 Year Amount  2019 $ 29  2020 22  2021 20  2022 15  2023 8  Thereafter 5  Total future minimum lease payments $ 99 

Membership Interests (Tables)

Membership Interests (Tables)	12 Months Ended
	Dec. 31, 2019
Membership Interests [Abstract]
Schedule Of Cash Capital Contributions	    Received Amount  November 21, 2019 $ 340  October 28, 2019 98  July 29, 2019 70  May 15, 2019 1,330  April 30, 2019 70  February 19, 2019 70  $ 1,978 
Schedule Of Distributions Paid	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  During 2018, our board of directors declared, and we paid, the following cash distributions to our members:     Declaration Date Payment Date Amount  October 24, 2018 November 6, 2018 $ 179  July 25, 2018 August 1, 2018 30  $ 209 
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, 2016 $ (20) $ (91) $ (111)  Defined benefit pension plans - 8 8  Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges 2 - 2  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 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 2 - 2  Amounts reclassified from accumulated other comprehensive income (loss) to capital account (4) - (4)  Balance at December 31, 2019 $ (18) $ (121) $ (139) 

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Pension And OPEB Plan Costs	  Year Ended December 31,  2019 2018 2017   Pension costs $ 63 $ 77 $ 85  OPEB costs 41 70 58  Total benefit costs 104 147 143  Less amounts recognized principally as property or a regulatory asset (27) (69) (98)  Net amounts recognized as operation and maintenance expense or other deductions $ 77 $ 78 $ 45 
Schedule Of Detailed Pension And OPEB Benefit Information	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2017 2019 2018 2017   Assumptions Used to Determine Net Periodic Pension and OPEB Costs:  Discount rate 4.18% 3.54% 4.05% 4.41% 3.73% 4.35%  Expected return on plan assets 5.42% 5.11% 5.17% 6.19% 6.20% 6.10%  Rate of compensation increase 4.53% 4.46% 3.33% - - -   Components of Net Pension and OPEB Costs:  Service cost $ 25 $ 27 $ 24 $ 6 $ 8 $ 7  Interest cost 128 121 131 43 44 47  Expected return on assets (119) (120) (115) (7) (9) (8)  Amortization of prior service cost (credit) - - - (20) (30) (20)  Amortization of net loss 29 49 45 19 57 32  Net periodic pension and OPEB costs $ 63 $ 77 $ 85 $ 41 $ 70 $ 58   Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:  Net loss (gain) $ - $ 67 $ (11) $ (22) $ (177) $ 139  Amortization of net loss (29) (49) (45) (19) (57) (32)  Plan amendments - - - - - (78)  Amortization of prior service (cost) credit - - - 20 30 20  Total recognized as regulatory assets or other comprehensive income (29) 18 (56) (21) (204) 49  Total recognized in net periodic pension and OPEB costs and as regulatory assets or other comprehensive income $ 34 $ 95 $ 29 $ 20 $ (134) $ 107 
Schedule Of Assumptions Used	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2017 2019 2018 2017   Assumptions Used to Determine Benefit Obligations at Period End:  Discount rate 3.13% 4.18% 3.54% 3.29% 4.41% 3.73%  Rate of compensation increase 4.64% 4.53% 4.46% - - - 
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,  2019 2018 2019 2018   Change in Projected Benefit Obligation:  Projected benefit obligation at beginning of year $ 3,162 $ 3,500 $ 1,006 $ 1,198  Service cost 25 27 6 8  Interest cost 128 121 43 44  Participant contributions - - 19 19  Plan amendments - - - -  Actuarial (gain) loss 367 (232) (5) (196)  Benefits paid (164) (175) (70) (67)  Annuity purchase (118) (79) - -  Projected benefit obligation at end of year $ 3,400 $ 3,162 $ 999 $ 1,006  Accumulated benefit obligation at end of year $ 3,283 $ 3,069 $ - $ -   Change in Plan Assets:  Fair value of assets at beginning of year $ 2,249 $ 2,600 $ 132 $ 149  Actual return (loss) on assets 486 (179) 25 (10)  Employer contributions 41 82 35 41  Participant contributions - - 19 19  Benefits paid (164) (175) (70) (67)  Annuity purchase (118) (79) - -  Fair value of assets at end of year $ 2,494 $ 2,249 $ 141 $ 132   Funded Status:  Projected benefit obligation at end of year $ (3,400) $ (3,162) $ (999) $ (1,006)  Fair value of assets at end of year 2,494 2,249 141 132  Funded status at end of year $ (906) $ (913) $ (858) $ (874) 
Schedule Of Amounts Recognized In Balance Sheet	  Pension Plans OPEB Plans  Year Ended December 31, Year Ended December 31,  2019 2018 2019 2018   Amounts Recognized in the Balance Sheet Consist of:  Liabilities:  Other current liabilities $ (5) $ (4) $ (15) $ (7)  Other noncurrent liabilities (901) (909) (843) (867)  Net liability recognized $ (906) $ (913) $ (858) $ (874)  Regulatory assets:  Net loss $ 531 $ 534 $ 129 $ 171  Prior service cost (credit) - - (37) (57)  Net regulatory asset recognized $ 531 $ 534 $ 92 $ 114  Accumulated other comprehensive net loss $ 120 $ 147 $ 1 $ 1 
Schedule Of Projected Benefit Obligations And Accumulated Benefit Obligations In Excess Of Plan Assets Fair Value	  At December 31,  2019 2018   Pension Plans with PBO and ABO in Excess of Plan Assets:  Projected benefit obligations $ 3,400 $ 3,162  Accumulated benefit obligations 3,283 3,069  Plan assets 2,494 2,249 
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 7.63% 401(h) accounts 6.26%  U.S. equity securities 6.80% Life insurance VEBA 6.04%  Real estate 5.20% Union VEBA 6.04%  Credit strategies 4.56% Non-union VEBA 1.80%  Fixed income securities 3.40% Shared retiree VEBA 1.80%  Weighted average (a) 5.22% Weighted average 5.90% _____________ (a) The 2020 expected long-term rate of return for the nonregulated portion of the Oncor Retirement Plan is 4.18%, and for Oncor’s portion of the Vistra Retirement Plan is 4.89% . 
Schedule Of Contributions	  Year Ended December 31,  2019 2018 2017   Pension plans contributions $ 41 $ 82 $ 149  Oncor OPEB Plans contributions 35 41 31  Total contributions $ 76 $ 123 $ 180 
Schedule Of Estimated Future Benefit Payments	  2020 2021 2022 2023 2024 2025-29   Pension plans $ 179 $ 183 $ 188 $ 191 $ 196 $ 996  Oncor OPEB Plans $ 50 $ 51 $ 53 $ 55 $ 56 $ 285 
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Assets Fair Value Measured On Recurring Basis	  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   At December 31, 2018  Level 1 Level 2 Level 3 Total   Asset Category  Equity securities:  U.S. $ 170 $ 2 $ - $ 172  International 239 - - 239  Fixed income securities:  Corporate bonds (a) - 930 - 930  U.S. Treasuries - 110 - 110  Other (b) - 69 - 69  Real estate - - 3 3  Total assets in the fair value hierarchy $ 409 $ 1,111 $ 3 1,523  Total assets measured at net asset value (c) 726  Total fair value of plan assets $ 2,249 _____________ (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, 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   At December 31, 2018  Level 1 Level 2 Level 3 Total   Asset Category  Interest-bearing cash $ 15 $ - $ - $ 15  Equity securities:  U.S. 21 - - 21  International 22 - - 22  Fixed income securities:  Corporate bonds (a) - 26 - 26  U.S. Treasuries - 3 - 3  Other (b) 28 1 - 29  Total assets in the fair value hierarchy $ 86 $ 30 $ - 116  Total assets measured at net asset value (c) 16  Total fair value of plan assets $ 132 _____________ (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,  2019 2018   Assumed Health Care Cost Trend Rates – Not Medicare Eligible:  Health care cost trend rate assumed for next year 7.20% 7.60%  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 2026   Assumed Health Care Cost Trend Rates – Medicare Eligible:  Health care cost trend rate assumed for next year 8.00% 8.70%  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 2027   1-Percentage Point Increase 1-Percentage Point Decrease   Sensitivity Analysis of Assumed Health Care Cost Trend Rates:  Effect on accumulated postretirement obligation $ 128 $ (106)  Effect on postretirement benefits cost 5 (4) 

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2019
Related-Party Transactions [Abstract]
Schedule Of Related Party Transactions	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, 2019 At December 31, 2018  STH Texas Transmission Total STH Texas Transmission Total   Federal income taxes payable (receivable) $ (2) $ (1) $ (3) $ 4 $ 1 $ 5  Texas margin taxes payable 22 - 22 21 - 21  Net payable (receivable) $ 20 $ (1) $ 19 $ 25 $ 1 $ 26  Cash payments made to (received from) members related to income taxes consisted of the following:   Year Ended December 31, 2019 Year Ended December 31, 2018 Year Ended December 31, 2017  STH Texas Transm. Total STH EFH Corp. Texas Transm. Total EFH Corp. Texas Transm. Total   Federal income taxes $ 45 $ 11 $ 56 $ 59 $ (19) $ 10 $ 50 $ (102) $ (12) $ (114)  Texas margin taxes 22 - 22 21 - - 21 20 - 20  Total payments (receipts) $ 67 $ 11 $ 78 $ 80 $ (19) $ 10 $ 71 $ (82) $ (12) $ (94) 

Supplementary Financial Infor_2

Supplementary Financial Information (Tables)	12 Months Ended
	Dec. 31, 2019
Supplementary Financial Information [Abstract]
Schedule Of Other Deductions And (Income)	Other Deductions and (Income)      Year Ended December 31,  2019 2018 2017   Professional fees $ 10 $ 12 $ 15  Sempra Acquisition related costs - 12 -  InfraREIT Acquisition related costs 9 - -  Recoverable Pension and OPEB - non-service costs 57 53 31  Non-recoverable pension and OPEB (Note 10) 4 6 5  AFUDC equity income (10) - -  Interest income (5) (1) (6)  Other (2) 2 1  Total other deductions and (income) - net $ 63 $ 84 $ 46 
Schedule Of Interest Expense And Related Charges	  Year Ended December 31,  2019 2018 2017   Interest $ 382 $ 358 $ 351  Amortization of debt issuance costs and discounts 9 6 3  Less AFUDC – capitalized interest portion (16) (13) (12)  Total interest expense and related charges $ 375 $ 351 $ 342 
Schedule Of Trade Accounts And Other Receivables	  At December 31,  2019 2018   Gross trade accounts and other receivables $ 666 $ 562  Allowance for uncollectible accounts (5) (3)  Trade accounts receivable – net $ 661 $ 559 
Summary of Investments And Other Property	  At December 31,  2019 2018   Assets related to employee benefit plans $ 119 $ 108  Land 12 12  Other 2 -  Total investments and other property $ 133 $ 120 
Schedule Of Property, Plant And Equipment	  Composite Depreciation Rate/ At December 31,  Avg. Life at December 31, 2019 2019 2018  Assets in service:  Distribution 2.8% / 35.8 years $ 14,007 $ 13,105  Transmission 2.9% / 35.0 years 11,094 8,568  Other assets 6.9% / 14.5 years 1,648 1,497  Total 26,749 23,170  Less accumulated depreciation 7,986 7,513  Net of accumulated depreciation 18,763 15,657  Construction work in progress 585 417  Held for future use 22 16  Property, plant and equipment – net $ 19,370 $ 16,090 
Schedule Of Intangible Assets	  At December 31, 2019 At December 31, 2018  Gross Gross  Carrying Accumulated Carrying Accumulated  Amount Amortization Net Amount Amortization Net  Identifiable intangible assets subject to amortization:  Land easements $ 575 $ 107 $ 468 $ 464 $ 101 $ 363  Capitalized software 933 430 503 787 385 402  Total $ 1,508 $ 537 $ 971 $ 1,251 $ 486 $ 765 
Schedule Of Estimated Aggregate Amortization Expenses	  Year Amortization Expense   2020 $ 61  2021 61  2022 61  2023 61  2024 60 
Schedule Of Employee Benefit Obligations And Other	  At December 31,  2019 2018   Retirement plans and other employee benefits $ 1,834 $ 1,858  Operating lease liabilities (Notes 1 and 8) 66 -  Investment tax credits 6 8  Other 74 77  Total employee benefit, operating lease and other obligations $ 1,980 $ 1,943 
Schedule Of Supplemental Cash Flow Information	  Year Ended December 31,  2019 2018 2017  Cash payments related to:   Interest $ 368 $ 368 $ 345  Less capitalized interest (16) (13) (12)  Interest payments (net of amounts capitalized) $ 352 $ 355 $ 333   Amount in lieu of income taxes (a):  Federal $ 56 $ 50 $ (114)  State 22 21 20  Total payments (refunds) in lieu of income taxes $ 78 $ 71 $ (94)   Noncash increase in operating lease obligation for ROU assets $ 38 $ - $ -   Noncash Sharyland 2017 Asset Exchange costs $ - $ - $ 383   Noncash investing and financing activity (b):  Acquisition:  Assets acquired $ 2,547 $ - $ -  Liabilities assumed (1,223) - -  Cash paid $ 1,324 $ - $ -   Noncash construction expenditures (c) $ 278 $ 174 $ 129 ______________ (a) See Note 12 for income tax related detail. (b) See Note 7 for more information on noncash debt exchanges related to InfraREIT Acquisition. (c) Represents end-of-period accruals.
Schedule Of Quarterly Information	  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   2018 First Quarter Second Quarter Third Quarter Fourth Quarter  Operating revenues $ 990 $ 1,021 $ 1,095 $ 995  Operating income 202 244 293 206  Net income 89 143 194 119 

Description Of Business And S_4

Description Of Business And Significant Accounting Policies (Narrative) (Details)

3 Months Ended

12 Months Ended

Dec. 31, 2019USD ($)

Sep. 30, 2019USD ($)

Jun. 30, 2019USD ($)

Mar. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Sep. 30, 2018USD ($)

Jun. 30, 2018USD ($)

Mar. 31, 2018USD ($)

Dec. 31, 2019USD ($)entity

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Jan. 01, 2019USD ($)

Mar. 09, 2018

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

$ 4,064,000,000

4,740,000,000

$ 4,064,000,000

Operating lease obligations

92,000,000

92,000,000

Revenues

1,079,000,000

$ 1,211,000,000

$ 1,041,000,000

$ 1,016,000,000

$ 995,000,000

$ 1,095,000,000

$ 1,021,000,000

$ 990,000,000

InfraREIT [Member]

Business And Significant Accounting Polices [Line Items]

Goodwill

$ 676,000,000

$ 676,000,000

Accounting Standards Update 2016-02 [Member]

Business And Significant Accounting Polices [Line Items]

Operating lease obligations

$ 82,000,000

Oncor Holdings [Member]

Business And Significant Accounting Polices [Line Items]

Number of disinterested directors | entity

2

Oncor Holdings [Member] | Oncor

Business And Significant Accounting Polices [Line Items]

Ownership interests acquired

0.22%

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_5

Description Of Business And Significant Accounting Policies (Schedule Of Adoption Of Topic 842) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease ROU assets and other	$ 92
Operating lease and other current liabilities	26
Employee benefit, operating lease and other obligations	66
Total operating lease liabilities	$ 92
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease ROU assets and other		$ 82
Operating lease and other current liabilities		26
Employee benefit, operating lease and other obligations		56
Total operating lease liabilities		$ 82

Acquisition Activity (Narrative

Acquisition Activity (Narrative) (Details) $ / shares in Units, $ in Millions	Feb. 18, 2020USD ($)	May 16, 2019USD ($)$ / shares	May 15, 2019MW	May 15, 2019kW	May 15, 2019property	May 15, 2019mi	May 15, 2019USD ($)	Jul. 21, 2017USD ($)mikW	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)mikW	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Repayment of debt																		$ 1,094	$ 825	$ 324
Members contribution																		1,978	284
Cash paid																		1,324		25
Goodwill									$ 4,740				$ 4,064				$ 4,740	4,740	4,064
InfraREIT Acquisition related costs																		9
Revenue																		4,347	4,101	3,958
Net income									133	$ 263	$ 139	$ 116	$ 119	$ 194	$ 143	$ 89		$ 651	$ 545	$ 419
Secured Debt [Member]
Business Acquisition [Line Items]
Outstanding debt acquired		$ 351
Sempra Energy [Member]
Business Acquisition [Line Items]
Partner capital contribution for business combination							$ 1,330
Subsequent Event [Member]
Business Acquisition [Line Items]
Members contribution	$ 87
Sharyland Merger Agreement [Member]
Business Acquisition [Line Items]
Purchase price								$ 408
Transmission of assets								383
Cash paid								$ 25
Number of assets transferred in circuit miles | mi								517
Power of number of transmission lines transferred | kW								345
Sharyland Distribution & Transmission Services (SDTS) [Member] | Sempra Texas Holdings [Member]
Business Acquisition [Line Items]
Partnership interest																		50.00%
InfraREIT [Member]
Business Acquisition [Line Items]
Price per share of common stock to stockholders and limited partners | $ / shares		$ 21
Purchase price		$ 1,324															1,324
Management agreement termination fee		40
Repayment of debt		602
Outstanding debt acquired		953
Transmission of assets									2,547								2,547	$ 2,547
Miles of assets transferred | mi						340												1,575
Cash paid		$ 1,275															1,275
Number of assets transferred in circuit miles | mi																		1,235
Power of number of transmission lines transferred			3,900	138														345
Number Of Operational Generation Facilities | property					20
Number Of Transmission Stations And Substations | property					50
Goodwill, Period Increase (Decrease)																		$ (11)
Goodwill									$ 676								676	$ 676
Revenue																	156
Net income																	$ 58

Acquisition Activity (Total Pur

Acquisition Activity (Total Purchase Price Paid) (Details) - USD ($) $ in Millions	May 16, 2019	Jul. 21, 2017	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2017
Purchase of outstanding InfrREIT shares and units				$ 1,324	$ 25
Sharyland Merger Agreement [Member]
Purchase of outstanding InfrREIT shares and units		$ 25
Total purchase price paid		$ 408
InfraREIT [Member]
Purchase of outstanding InfrREIT shares and units	$ 1,275		$ 1,275
Certain transaction costs of InfraREIT paid by Oncor			49
Total purchase price paid	$ 1,324		1,324
Management termination fee			$ 40

Acquisition Activity (Assets An

Acquisition Activity (Assets And Liabilities Assumed) (Details) - USD ($) $ in Millions	May 16, 2019	Jul. 21, 2017	Dec. 31, 2019	Dec. 31, 2018
Goodwill			$ 4,740	$ 4,064
Sharyland Merger Agreement [Member]
Total assets acquired		$ 383
Total purchase price paid		$ 408
InfraREIT [Member]
Current assets			45
Property, plant and equipment - net			1,800
Goodwill			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

Acquisition Activity (Pro Forma

Acquisition Activity (Pro Forma Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
InfraREIT [Member]
Oncor Consolidated Pro Forma Revenues	$ 4,431	$ 4,318

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	Jul. 09, 2019USD ($)	Sep. 14, 2018USD ($)	Jul. 21, 2017USD ($)mikW	Sep. 30, 2018USD ($)	May 31, 2019USD ($)	Mar. 31, 2017USD ($)	Nov. 26, 2017USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 30, 2019USD ($)	Apr. 08, 2019USD ($)
Public Utilities, General Disclosures [Line Items]
U.S. federal statutory rate								21.00%	21.00%	35.00%
Reconciliation of all costs incurred with revenues							$ 87
Net operating cost savings	$ 16
Authorized under-recovery reconciliation costs	$ 6
Decrease in revenue requirement				$ 144
Reduction related to amortization of excess deferred income taxes				$ 75
Refund of tax rate differential					$ 9
DCRF increase on annual basis											$ 25	$ 29
Increase (decrease) in liability for deferred income taxes						$ 3
Authorized return on equity								9.80%	10.25%
Regulatory capitalization ratio, debt								57.50%	60.00%
Regulatory capitalization ratio, equity								42.50%	40.00%
Increase in regulatory liabililty		$ 6
Sharyland Merger Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Transmission of assets			$ 383
Number of assets transferred in circuit miles | mi			517
Power of number of transmission lines transferred | kW			345

Regulatory Matters (Components

Regulatory Matters (Components Of Regulatory Assets And Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Regulatory Assets And Liabilities [Line Items]
Carrying Amount, Regulatory Assets	$ 1,775	$ 1,691
Carrying Amount, Regulatory Liabilities	2,793	2,697
Net regulatory assets (liabilities)	$ (1,018)	(1,006)
Estimated Net Removal Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Lives of related assets
Carrying Amount, Regulatory Liabilities	$ 1,178	1,023
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	$ 1,574	1,571
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	$ 30	89
Other Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Various
Carrying Amount, Regulatory Liabilities	$ 11	14
Employee Retirement Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 623	648
Employee Retirement Costs Being Amortized [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	8 years
Carrying Amount, Regulatory Assets	$ 262	297
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	$ 79	73
Self-Insurance Reserve (Primarily Storm Recovery Costs) Being Amortized [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	8 years
Carrying Amount, Regulatory Assets	$ 309	351
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	$ 238	59
Securities Reacquisition Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Lives of related debt
Carrying Amount, Regulatory Assets	$ 29	10
Deferred Conventional Meter And Metering Facilities Depreciation [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	1 year
Carrying Amount, Regulatory Assets	$ 15	36
Under-recovered AMS Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	8 years
Carrying Amount, Regulatory Assets	$ 170	185
Energy Efficiency Performance Bonus [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	1 year or less
Carrying Amount, Regulatory Assets	$ 9	7
Wholesale Distribution Substation Service [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	To be determined
Carrying Amount, Regulatory Assets	$ 34	15
Other Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Remaining Rate Recovery/Amortization Period	Various
Carrying Amount, Regulatory Assets	$ 7	$ 10

Revenues (Narrative) (Details)

Revenues (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)customeritem	Dec. 31, 2018USD ($)	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Approved bonus | $	$ 9	$ 7
Number of REPS | customer	90
Number of counterparties | item	2
REP Subsidiary One [Member] | Revenue Benchmark [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	23.00%	23.00%	22.00%
REP Subsidiary Two [Member] | Revenue Benchmark [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	18.00%	19.00%	18.00%

Revenues (Disaggregation Of Rev

Revenues (Disaggregation Of Revenues) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	$ 3,292	$ 3,068
Revenues collected for pass-through expenses	1,055	1,033
Total operating revenues	4,347	4,101	$ 3,958
Distribution Base Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	2,143	2,139
Transmission Base Revenues (TCOS Revenues) [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	1,072	858
Transmission Base Revenues (TCOS Revenues) [Member] | Third-Party Wholesale Customers [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	681	548
Transmission Base Revenues (TCOS Revenues) [Member] | REPS Serving Oncor Distribution Customers, Through TCRF [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	391	310
Other Miscellaneous Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenues contributing to earnings	77	71
TCRF - Third-party Wholesale Transmission Service [Member]
Disaggregation of Revenue [Line Items]
Revenues collected for pass-through expenses	1,005	962
EECRF And Other Regulatory Charges [Member]
Disaggregation of Revenue [Line Items]
Revenues collected for pass-through expenses	$ 50	$ 71

Provision In Lieu Of Income T_3

Provision In Lieu Of Income Taxes (Narrative) (Details) - USD ($)	Dec. 22, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision In Lieu Of Income Taxes [Abstract]
U.S. federal statutory rate			21.00%	21.00%	35.00%
Re-measurement of liability in lieu of deferred income taxes	$ 1,600,000,000				$ 21,000,000
Increase (decrease) in liability for deferred income taxes		$ 3,000,000
Net liability in lieu of deferred income taxes			$ 1,821,000,000	$ 1,602,000,000
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, 2019	Dec. 31, 2018
Provision In Lieu Of Income Taxes [Abstract]
Deferred tax assets, Employee benefit liabilities	$ 224	$ 234
Deferred tax assets, Regulatory liabilities	51	55
Deferred tax assets, Other	28	6
Total	303	295
Deferred tax liabilities, Property, plant and equipment	1,851	1,651
Deferred tax liabilities, Regulatory assets	272	245
Deferred Tax Liabilities, Other	1	1
Total	2,124	1,897
Liability in lieu of deferred income taxes - net	$ 1,821	$ 1,602

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision In Lieu Of Income Taxes [Abstract]
Current: U.S. federal	$ 69	$ 112	$ (55)
Current: State	22	21	20
Deferred: U.S. federal	49	21	303
Amortization of investment tax credits	(2)	(2)	(2)
Total reported in operating expenses	138	152	266
U.S. federal	(21)	(32)	(5)
Deferred federal	6	(3)	6
Total reported in other income and deductions	(15)	(35)	1
Total provision in lieu of income taxes	$ 123	$ 117	$ 267

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision In Lieu Of Income Taxes [Abstract]
Income before provision in lieu of income taxes	$ 774	$ 662	$ 686
Provision in lieu of income taxes at the U.S. federal statutory rate of 21% for 2019 and 2018 and 35% for 2017	163	139	240
Amortization of investment tax credits - net of deferred tax effect	(2)	(2)	(2)
Amortization of excess deferred taxes	(52)	(18)	(1)
Impact of federal statutory rate change 35% to 21%			21
Texas margin tax, net of federal tax benefit	17	17	13
Nontaxable gains on benefit plan investments	(2)	(1)	(4)
Other	(1)	(18)
Total provision in lieu of income taxes	$ 123	$ 117	$ 267
Effective rate	15.90%	17.70%	38.90%
U.S. federal statutory rate	21.00%	21.00%	35.00%

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) $ in Millions	Sep. 06, 2019	May 16, 2019USD ($)	May 15, 2019USD ($)	May 09, 2019	Nov. 30, 2017USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Line of Credit Facility [Line Items]
Short-term Debt						$ 46	$ 813
Payment of acquired entity credit facilities		$ 114
Borrowing capacity available under the credit facility						2,000	2,000
Bridge Loan [Member]
Line of Credit Facility [Line Items]
Short-term Debt			$ 600
Interest rate per annum				0.075%
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Outstanding borrowing under the revolving credit facility						$ 10	9
Outstanding borrowing, interest rate						1.20%
Commitment fee						0.125%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 2,000
Number of revolving credit facilities extension options | item					2
Extension period for revolving line of credit					1 year
Credit facility, term					5 years
Expiration of revolving credit facility						Nov. 1, 2022
Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Additional increase in borrowing capacity amount					$ 100
Libor rate depending on credit ratings						0.50%
Commitment fee						0.225%
Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Additional increase in borrowing capacity amount					$ 400
Libor rate depending on credit ratings						0.00%
Commitment fee						0.075%
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Outstanding borrowing under the revolving credit facility						$ 46	$ 813
London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Spread over variable rate						1.00%
London Interbank Offered Rate (LIBOR) [Member] | Bridge Loan [Member]
Line of Credit Facility [Line Items]
Interest rate per annum			0.65%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Spread over variable rate						1.00%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Libor rate depending on credit ratings						1.50%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Libor rate depending on credit ratings						0.875%
Federal Funds Effective Rate [Member]
Line of Credit Facility [Line Items]
Spread over variable rate	0.50%
Federal Funds Effective Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Spread over variable rate						0.50%

Short-Term Borrowings (Schedule

Short-Term Borrowings (Schedule Of Short-Term Borrowings) (Details) - USD ($) $ in Millions	Sep. 06, 2019	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Total borrowing capacity		$ 2,000	$ 2,000
Available unused credit		1,944	1,178
Commercial Paper [Member]
Short-term Debt [Line Items]
Outstanding		$ (46)	$ (813)
Interest Rate		1.84%	2.74%
Letter of Credit [Member]
Short-term Debt [Line Items]
Outstanding		$ (10)	$ (9)
Interest Rate		1.20%
London Interbank Offered Rate (LIBOR) [Member]
Short-term Debt [Line Items]
Spread over variable rate		1.00%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Spread over variable rate		1.00%
Federal Funds Effective Rate [Member]
Short-term Debt [Line Items]
Spread over variable rate	0.50%
Federal Funds Effective Rate [Member] | Revolving 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. 12, 2019	Sep. 06, 2019	May 16, 2019	Nov. 30, 2019	May 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Long-Term Debt [Line Items]
Repayments of long-term debt						$ 1,094,000,000	$ 825,000,000	$ 324,000,000
Proceeds from sale of Notes	$ 689,000,000				$ 1,297,000,000
Redemption percentage						100.00%
Percentage of fair value of cost of property additions certified to the Deed of Trust collateral agent						85.00%
Available bond credits						$ 2,771,000,000
Future debt subject to property additions to the Deed of Trust						2,410,000,000
Estimated fair value of our long-term debt including current maturities						10,003,000,000	7,086,000,000
InfraREIT [Member]
Long-Term Debt [Line Items]
Repayments of long-term debt						$ 488,000,000
Aggregate principal amount			$ 288,000,000
Accrued interest			5,000,000
Make-whole fees			19,000,000
London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt [Line Items]
Spread over variable rate						1.00%
Federal Funds Effective Rate [Member]
Long-Term Debt [Line Items]
Spread over variable rate		0.50%
Term Loan Credit Agreement Maturing December 9, 2019 [Member]
Long-Term Debt [Line Items]
Repayments of long-term debt				$ 350,000,000
Subsidiary Term Loan [Member] | InfraREIT [Member]
Long-Term Debt [Line Items]
Repayments of long-term debt			200,000,000
6.47% Senior Notes, Series A, due September 30, 2030 [Member]
Long-Term Debt [Line Items]
Debt modification principal amount						$ 87,000,000
7.25% Senior Notes, Series B, due December 30, 2029 [Member]
Long-Term Debt [Line Items]
Debt modification principal amount						38,000,000
8.50% Senior Notes, Series C, due December 30, 2020 [Member]
Long-Term Debt [Line Items]
Debt modification principal amount						14,000,000
3.86% Senior Notes, Series A, due December 3, 2025 [Member]
Long-Term Debt [Line Items]
Debt modification principal amount						174,000,000
3.86% Senior Notes, Series B, due January 14, 2026 [Member]
Long-Term Debt [Line Items]
Debt modification principal amount						38,000,000
Term Loan Credit Agreement Maturing October 6, 2020 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Long-Term Debt [Line Items]
Spread over variable rate		0.50%
Term Loan Credit Agreement Maturing October 6, 2020 [Member] | One-Month London Interbank Offered Rate [Member]
Long-Term Debt [Line Items]
Spread over variable rate		1.00%
Note Purchase Agreements [Member]
Long-Term Debt [Line Items]
Debt principal amount						6,000,000
New Indenture Notes [Member]
Long-Term Debt [Line Items]
Proceeds from issuance of debt						0
Secured Debt [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						8,221,000,000	6,126,000,000
Secured Debt [Member] | 2.15% Fixed Senior Notes Due June 1, 2019 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount							250,000,000
Secured Debt [Member] | 3.70% Fixed Senior Notes Due November 15, 2028 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						650,000,000	350,000,000
Secured Debt [Member] | 4.10% Fixed Senior Notes Due November 15, 2048 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						450,000,000	450,000,000
Secured Debt [Member] | 5.75% Fixed Senior Notes Due March 15, 2029 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						318,000,000	318,000,000
Secured Debt [Member] | 7.00% Fixed Debentures Due September 1, 2022 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						482,000,000	482,000,000
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] | 7.25% Senior Notes, Series B, due December 30, 2029 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						36,000,000
Secured Debt [Member] | 8.50% Senior Notes, Series C, due December 30, 2020 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						14,000,000
Secured Debt [Member] | 3.86% Senior Notes, Series A, due December 3, 2025 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						174,000,000
Secured Debt [Member] | 3.86% Senior Notes, Series B, due January 14, 2026 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						38,000,000
Secured Debt [Member] | 3.10% Senior Notes, due September 15, 2049 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						700,000,000
Secured Debt [Member] | 2.75% Senior Notes due June 1, 2024 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						500,000,000
Secured Debt [Member] | 3.80% Senior Notes, due June 1, 2049 [Member]
Long-Term Debt [Line Items]
Aggregate principal amount						500,000,000
Unsecured Debt [Member] | Term Loan Credit Agreement Maturing December 9, 2019 [Member]
Long-Term Debt [Line Items]
Term loan							$ 350,000,000
Unsecured Debt [Member] | Term Loan Credit Agreement Maturing October 6, 2020 [Member]
Long-Term Debt [Line Items]
Term loan						$ 460,000,000
InfraREIT [Member]
Long-Term Debt [Line Items]
Repayments of long-term debt			602,000,000
Debt principal amount			$ 351,000,000

Long-Term Debt (Schedule Of Lon

Long-Term Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	$ (56)	$ (41)
Less amount due currently	(608)	(600)
Long-term debt, less amounts due currently	8,017	5,835
Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	8,221	6,126
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 8,681	$ 6,476
2.15% Fixed Senior Notes Due June 1, 2019 [Member]
Debt Instrument [Line Items]
Interest percentage	2.15%	2.15%
Due date	Jun. 1, 2019
2.15% Fixed Senior Notes Due June 1, 2019 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt		$ 250
5.75% Fixed Senior Notes Due September 30, 2020 [Member]
Debt Instrument [Line Items]
Interest percentage	5.75%	5.75%
Due date	Sep. 30, 2020
5.75% Fixed Senior Notes Due September 30, 2020 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 126	$ 126
8.50% Senior Notes, Series C, due December 30, 2020 [Member]
Debt Instrument [Line Items]
Interest percentage	8.50%	8.50%
Due date	Dec. 30, 2020
8.50% Senior Notes, Series C, due December 30, 2020 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 14
4.10% Fixed Senior Notes Due June 1, 2022 [Member]
Debt Instrument [Line Items]
Interest percentage	4.10%	4.10%
Due date	Jun. 1, 2022
4.10% Fixed Senior Notes Due June 1, 2022 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400	$ 400
7.00% Fixed Debentures Due September 1, 2022 [Member]
Debt Instrument [Line Items]
Interest percentage	7.00%
Due date	Sep. 1, 2022
7.00% Fixed Debentures Due September 1, 2022 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 482	482
2.75% Senior Notes due June 1, 2024 [Member]
Debt Instrument [Line Items]
Interest percentage	2.75%
Due date	Jun. 1, 2024
2.75% Senior Notes due June 1, 2024 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500
2.95% Fixed Senior Notes Due April 1, 2025 [Member]
Debt Instrument [Line Items]
Interest percentage	2.95%
Due date	Apr. 1, 2025
2.95% Fixed Senior Notes Due April 1, 2025 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 350	$ 350
3.86% Senior Notes, Series A, due December 3, 2025 [Member]
Debt Instrument [Line Items]
Interest percentage	3.86%	3.86%
Due date	Dec. 3, 2025
3.86% Senior Notes, Series A, due December 3, 2025 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 174
3.86% Senior Notes, Series B, due January 14, 2026 [Member]
Debt Instrument [Line Items]
Interest percentage	3.86%	3.86%
Due date	Jan. 14, 2026
3.86% Senior Notes, Series B, due January 14, 2026 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 38
3.70% Fixed Senior Notes Due November 15, 2028 [Member]
Debt Instrument [Line Items]
Interest percentage	3.70%	3.70%
Due date	Nov. 15, 2028
3.70% Fixed Senior Notes Due November 15, 2028 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 650	$ 350
5.75% Fixed Senior Notes Due March 15, 2029 [Member]
Debt Instrument [Line Items]
Interest percentage	5.75%	5.75%
Due date	Mar. 15, 2029
5.75% Fixed Senior Notes Due March 15, 2029 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 318	$ 318
7.25% Senior Notes, Series B, due December 30, 2029 [Member]
Debt Instrument [Line Items]
Interest percentage	7.25%	7.25%
Due date	Dec. 30, 2029
7.25% Senior Notes, Series B, due December 30, 2029 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 36
6.47% Senior Notes, Series A, due September 30, 2030 [Member]
Debt Instrument [Line Items]
Interest percentage	6.47%	6.47%
Due date	Sep. 30, 2030
6.47% Senior Notes, Series A, due September 30, 2030 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 83
7.00% Fixed Senior Notes Due May 1, 2032 [Member]
Debt Instrument [Line Items]
Interest percentage	7.00%	7.00%
Due date	May 1, 2032
7.00% Fixed Senior Notes Due May 1, 2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500	$ 500
7.25% Fixed Senior Notes Due January 15, 2033 [Member]
Debt Instrument [Line Items]
Interest percentage	7.25%	7.25%
Due date	Jan. 15, 2033
7.25% Fixed Senior Notes Due January 15, 2033 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 350	$ 350
7.50% Fixed Senior Notes Due September 1, 2038 [Member]
Debt Instrument [Line Items]
Interest percentage	7.50%	7.50%
Due date	Sep. 1, 2038
7.50% Fixed Senior Notes Due September 1, 2038 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 300	$ 300
5.25% Fixed Senior Notes Due September 30, 2040 [Member]
Debt Instrument [Line Items]
Interest percentage	5.25%	5.25%
Due date	Sep. 30, 2040
5.25% Fixed Senior Notes Due September 30, 2040 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 475	$ 475
4.55% Fixed Senior Notes Due December 1, 2041 [Member]
Debt Instrument [Line Items]
Interest percentage	4.55%	4.55%
Due date	Dec. 1, 2041
4.55% Fixed Senior Notes Due December 1, 2041 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 400	$ 400
5.30% Fixed Senior Notes Due June 1, 2042 [Member]
Debt Instrument [Line Items]
Interest percentage	5.30%	5.30%
Due date	Jun. 1, 2042
5.30% Fixed Senior Notes Due June 1, 2042 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500	$ 500
3.75% Fixed Senior Notes Due April 1, 2045 [Member]
Debt Instrument [Line Items]
Interest percentage	3.75%	3.75%
Due date	Apr. 1, 2045
3.75% Fixed Senior Notes Due April 1, 2045 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 550	$ 550
3.80% Fixed Senior Notes Due September 30, 2047 [Member]
Debt Instrument [Line Items]
Interest percentage	3.80%	3.80%
Due date	Sep. 30, 2047
3.80% Fixed Senior Notes Due September 30, 2047 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 325	$ 325
4.10% Fixed Senior Notes Due November 15, 2048 [Member]
Debt Instrument [Line Items]
Interest percentage	4.10%	4.10%
Due date	Nov. 15, 2048
4.10% Fixed Senior Notes Due November 15, 2048 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 450	$ 450
3.80% Senior Notes, due June 1, 2049 [Member]
Debt Instrument [Line Items]
Interest percentage	3.80%	3.80%
Due date	Jun. 1, 2049
3.80% Senior Notes, due June 1, 2049 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 500
3.10% Senior Notes, due September 15, 2049 [Member]
Debt Instrument [Line Items]
Interest percentage	3.10%	3.10%
Due date	Sep. 15, 2049
3.10% Senior Notes, due September 15, 2049 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Secured long-term debt	$ 700
Term Loan Credit Agreement Maturing December 9, 2019 [Member]
Debt Instrument [Line Items]
Due date	Dec. 9, 2019
Term Loan Credit Agreement Maturing December 9, 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Term loan		$ 350
Term Loan Credit Agreement Maturing October 6, 2020 [Member]
Debt Instrument [Line Items]
Due date	Oct. 6, 2020
Term Loan Credit Agreement Maturing October 6, 2020 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Term loan	$ 460

Long-Term Debt (Schedule Of L_2

Long-Term Debt (Schedule Of Long-Term Debt Maturity) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Long-Term Debt [Abstract]
2020	$ 608
2021	9
2022	891
2023	10
2024	510
Thereafter	6,653
Unamortized discount and debt issuance costs	(56)	$ (41)
Total	$ 8,625

Commitments And Contingencies_2

Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Commitments And Contingencies [Abstract]
Lessee, Operating Lease, Term of Contract	20 years
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	15 years
Business Combination, Minimum Capital Expenditures Over Five Year Period	$ 7,500
2020 required efficiency spending amount	$ 50
Percentage of full time employees represented by labor union	18.00%
Expiration date of collective bargaining agreement	Oct. 25, 2022

Commitments And Contingencies_3

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

Commitments And Contingencies_4

Commitments And Contingencies (Schedule Of Lease Costs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
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) $ in Millions	Dec. 31, 2019USD ($)
Commitments And Contingencies [Abstract]
2020	$ 28
2021	25
2022	19
2023	13
2024	8
Thereafter	3
Total undiscounted lease payments	96
Less imputed interest	(4)
Total future minimum lease payments	$ 92

Commitments And Contingencies_6

Commitments And Contingencies (Schedule Of Future Minimum Lease Payments Under Operating Leases) (Details) $ in Millions	Dec. 31, 2019USD ($)
Commitments And Contingencies [Abstract]
2019	$ 29
2020	22
2021	20
2022	15
2023	8
Thereafter	5
Total future minimum lease payments	$ 99

Membership Interests (Narrative

Membership Interests (Narrative) (Details) - USD ($) $ in Millions	Feb. 18, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 21, 2020
Subsequent Event [Line Items]
Regulatory capitalization ratio, debt		57.50%	60.00%
Regulatory capitalization ratio, equity		42.50%	40.00%
Regulatory liability balance		$ 751
Members contribution		$ 1,978	$ 284
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash restricted for distribution under the capital structure restriction				$ 91
Members contribution	$ 87

Membership Interests (Schedule

Membership Interests (Schedule Of Cash Capital Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Members contribution	$ 1,978	$ 284
November 21, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	340
October 28, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	98
July 29, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	70
May 15, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	1,330
April 30, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	70
February 19, 2019 [Member]
Related Party Transaction [Line Items]
Members contribution	$ 70

Membership Interests (Schedul_2

Membership Interests (Schedule Of Distributions Paid) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends Payable [Line Items]
Amount	$ 319	$ 209	$ 237
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
Payment One FY 2018 [Member]
Dividends Payable [Line Items]
Declaration Date		Oct. 24, 2018
Payment Date		Nov. 6, 2018
Amount		$ 179
Payment Two FY 2018 [Member]
Dividends Payable [Line Items]
Declaration Date		Jul. 25, 2018
Payment Date		Aug. 1, 2018
Amount		$ 30

Membership Interests (Schedul_3

Membership Interests (Schedule Of Changes To Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (164)	$ (101)	$ (111)
Balance at end of period	(139)	(164)	(101)
Cash Flow Hedges - Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(16)	(18)	(20)
Defined benefit pension plans
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges	2	2	2
Amounts reclassified from accumulated other comprehensive income (loss) to the capital account	(4)
Balance at end of period	(18)	(16)	(18)
Defined Benefit Pension and OPEB Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(148)	(83)	(91)
Defined benefit pension plans	27	(65)	8
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges
Amounts reclassified from accumulated other comprehensive income (loss) to the capital account
Balance at end of period	(121)	(148)	(83)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(164)	(101)	(111)
Defined benefit pension plans	27	(65)	8
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges	2	2	2
Amounts reclassified from accumulated other comprehensive income (loss) to the capital account	(4)
Balance at end of period	$ (139)	$ (164)	$ (101)

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)item	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets		$ 1,775,000,000	$ 1,691,000,000
Earning period		3 years
Number of OPEB plans | item		2
Rolling period		4 years
Percentage of gains and losses		25.00%
Second pool representation of total investments, percentage		27.00%
Cash contributions		$ 76,000,000	123,000,000	$ 180,000,000
Thrift Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions		$ 20,000,000	19,000,000	17,000,000
Oncor Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of corporate bonds | item		927
Pension And OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets		$ 964,000,000,000	1,018,000,000,000
Defined Benefit Pension Plans [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of net loss	$ 43,000,000
Amortization of prior service cost	0
Defined Benefit Pension Plans [Member] | Scenario, Forecast [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of net loss	5,000,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain		(367,000,000)	232,000,000
Net gain (loss)			(67,000,000)	11,000,000
Expected return on assets		119,000,000	120,000,000	115,000,000
Unfunded liability		(906,000,000)	(913,000,000)
Amortization of net loss		(29,000,000)	$ (49,000,000)	$ (45,000,000)
Expected funding, 2019		177,000,000
Expected funding, 2019 to 2023		$ 571,000,000
Discount rate		4.18%	3.54%	4.05%
Expected return on plan assets		5.42%	5.11%	5.17%
Cash contributions		$ 41,000,000	$ 82,000,000	$ 149,000,000
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain		5,000,000	196,000,000
Net gain (loss)		22,000,000	177,000,000	(139,000,000)
Expected return on assets		7,000,000	9,000,000	8,000,000
Unfunded liability		$ (858,000,000)	(874,000,000)
Number of corporate bonds | item		361
Amortization of net loss		$ (19,000,000)	(57,000,000)	(32,000,000)
Amortization of prior service cost		(20,000,000)	$ (30,000,000)	$ (20,000,000)
Expected funding, 2019		35,000,000
Expected funding, 2019 to 2023		$ 176,000,000
Discount rate		4.41%	3.73%	4.35%
Expected return on plan assets		6.19%	6.20%	6.10%
Cash contributions		$ 35,000,000	$ 41,000,000	$ 31,000,000
OPEB Plan [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in projected benefit obligation	9,000,000
Amortization of net loss	10,000,000
Amortization of prior service cost	20,000,000
OPEB Plan [Member] | Scenario, Forecast [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of net loss	0
Amortization of prior service cost	$ 0
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 104	$ 147	$ 143
Less amounts deferred principally as property or a regulatory asset	(27)	(69)	(98)
Net amounts recognized as operation and maintenance expense or other deductions	77	78	45
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	63	77	85
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 41	$ 70	$ 58

Employee Benefit Plans (Pension

Employee Benefit Plans (Pension and OPEB Costs Recognized as Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net OPEB costs:
Net costs	$ 104	$ 147	$ 143
Pension Plan [Member]
Assumptions Used to Determine Net Periodic Pension and OPEB Costs:
Discount rate	4.18%	3.54%	4.05%
Expected return on plan assets	5.42%	5.11%	5.17%
Rate of compensation increase	4.53%	4.46%	3.33%
Components of net OPEB costs:
Service cost	$ 25	$ 27	$ 24
Interest cost	128	121	131
Expected return on assets	(119)	(120)	(115)
Amortization of net loss	29	49	45
Net costs	63	77	85
Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:
Net loss (gain)		67	(11)
Amortization of net loss	(29)	(49)	(45)
Plan amendments
Total recognized as regulatory assets or other comprehensive income	(29)	18	(56)
Net amounts recognized as expense	$ 34	$ 95	$ 29
OPEB Plan [Member]
Assumptions Used to Determine Net Periodic Pension and OPEB Costs:
Discount rate	4.41%	3.73%	4.35%
Expected return on plan assets	6.19%	6.20%	6.10%
Components of net OPEB costs:
Service cost	$ 6	$ 8	$ 7
Interest cost	43	44	47
Expected return on assets	(7)	(9)	(8)
Amortization of prior service cost (credit)	(20)	(30)	(20)
Amortization of net loss	19	57	32
Net costs	41	70	58
Other Changes in Plan Assets and Benefit Obligations Recognized as Regulatory Assets or in Other Comprehensive Income:
Net loss (gain)	(22)	(177)	139
Amortization of net loss	(19)	(57)	(32)
Plan amendments			(78)
Amortization of prior service cost (credit)	20	30	20
Total recognized as regulatory assets or other comprehensive income	(21)	(204)	49
Net amounts recognized as expense	$ 20	$ (134)	$ 107

Employee Benefit Plans (Assumpt

Employee Benefit Plans (Assumptions Used To Determine Benefit Obligations) (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.13%	4.18%	3.54%
Rate of compensation increase	4.64%	4.53%	4.46%
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.29%	4.41%	3.73%

Employee Benefit Plans (Change

Employee Benefit Plans (Change In Project Benefit Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of year	$ 3,162	$ 3,500
Service cost	25	27	$ 24
Interest cost	128	121	131
Participant contributions
Plan amendments
Actuarial (gain) loss	367	(232)
Benefits paid	(164)	(175)
Annuity purchase	(118)	(79)
Projected benefit obligation at end of year	3,400	3,162	3,500
Accumulated benefit obligation at end of year	3,283	3,069
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of year	1,006	1,198
Service cost	6	8	7
Interest cost	43	44	47
Participant contributions	19	19
Plan amendments			(78)
Actuarial (gain) loss	(5)	(196)
Benefits paid	(70)	(67)
Annuity purchase
Projected benefit obligation at end of year	999	1,006	$ 1,198
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 76	$ 123	$ 180
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets at beginning of year	2,249	2,600
Actual return (loss) on assets	486	(179)
Employer contributions	41	82	149
Participant contributions
Benefits paid	(164)	(175)
Annuity purchase	(118)	(79)
Fair value of assets at end of year	2,494	2,249	2,600
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets at beginning of year	132	149
Actual return (loss) on assets	25	(10)
Employer contributions	35	41	31
Participant contributions	19	19
Benefits paid	(70)	(67)
Annuity purchase
Fair value of assets at end of year	$ 141	$ 132	$ 149

Employee Benefit Plans (Funded

Employee Benefit Plans (Funded Status) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at end of year	$ (3,400)	$ (3,162)	$ (3,500)
Fair value of assets at end of year	2,494	2,249	2,600
Funded status at end of year	(906)	(913)
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at end of year	(999)	(1,006)	(1,198)
Fair value of assets at end of year	141	132	$ 149
Funded status at end of year	$ (858)	$ (874)

Employee Benefit Plans (Amounts

Employee Benefit Plans (Amounts Recognized In Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive net loss	$ (139)	$ (164)	$ (101)	$ (111)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	(5)	(4)
Other noncurrent liabilities	(901)	(909)
Net liability recognized	(906)	(913)
Net loss	531	534
Net regulatory asset recognized	531	534
Accumulated other comprehensive net loss	120	147
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	(15)	(7)
Other noncurrent liabilities	(843)	(867)
Net liability recognized	(858)	(874)
Net loss	129	171
Prior service cost (credit)	(37)	(57)
Net regulatory asset recognized	92	114
Accumulated other comprehensive net loss	$ 1	$ 1

Employee Benefit Plans (Sched_2

Employee Benefit Plans (Schedule Of Assumed Health Care Cost Trend Rates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Effect on accumulated postretirement obligation, 1-Percentage Point Increase	$ 128
Effect on accumulated postretirement obligation, 1-Percentage Point Decrease		$ (106)
Effect on postretirement benefits cost, 1-Percentage Point Increase	$ 5
Effect on postretirement benefits cost, 1-Percentage Point Decrease		$ (4)
Not Medicare Eligible [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care and prescription drug cost trend rate assumed for next year	7.20%	7.60%
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	2026
Medicare Eligible [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care and prescription drug cost trend rate assumed for next year	8.00%	8.70%
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	2027

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, 2019	Dec. 31, 2018
Employee Benefit Plans [Abstract]
Projected benefit obligations	$ 3,400	$ 3,162
Accumulated benefit obligations	3,283	3,069
Plan assets	$ 2,494	$ 2,249

Employee Benefit Plans (Sched_4

Employee Benefit Plans (Schedule Of Target Asset Allocation Ranges By Asset Category) (Details)	Dec. 31, 2019
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, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 2,494	$ 2,249	$ 2,600
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	141	132	$ 149
Fair Value, Inputs, Level 1 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	484	409
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	80	86
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	6	15
Fair Value, Inputs, Level 1 [Member] | US Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	194	170
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	21
Fair Value, Inputs, Level 1 [Member] | International Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	290	239
Fair Value, Inputs, Level 1 [Member] | International Equities [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	28	22
Fair Value, Inputs, Level 1 [Member] | Other [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	22	28
Fair Value, Inputs, Level 2 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,121	1,111
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	36	30
Fair Value, Inputs, Level 2 [Member] | US Equities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	2	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
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	908	930
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	31	26
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	147	110
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	3	3
Fair Value, Inputs, Level 2 [Member] | Other [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	63	69
Fair Value, Inputs, Level 2 [Member] | Other [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	2	1
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	3	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	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	1,608	1,523
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	116	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	6	15
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	196	172
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	21
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	291	239
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	28	22
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	908	930
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	31	26
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	147	110
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	3	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	63	69
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	24	29
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	3
NAV [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	886	726
NAV [Member] | OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 25	$ 16

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, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.22%
Pension Plan [Member] | International Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	7.63%
Pension Plan [Member] | US Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	6.80%
Pension Plan [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	5.20%
Pension Plan [Member] | Credit Strategies [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	4.56%
Pension Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	3.40%
Pension Plan [Member] | Oncor Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	4.18%
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	1.80%
OPEB Plan [Member] | 401(h) Accounts [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	6.26%
OPEB Plan [Member] | Life Insurance VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	6.04%
OPEB Plan [Member] | Union VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	6.04%
OPEB Plan [Member] | Non-union VEBA [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	1.80%
OPEB Plan [Member] | Vistra Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected long-term rate of return	4.89%

Employee Benefit Plans (Sched_7

Employee Benefit Plans (Schedule Of Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total contributions	$ 76	$ 123	$ 180
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions	41	82	149
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total contributions	$ 35	$ 41	$ 31

Employee Benefit Plans (Sched_8

Employee Benefit Plans (Schedule Of Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2019USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2019	$ 179
2020	183
2021	188
2022	191
2023	196
2024-28	996
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2019	50
2020	51
2021	53
2022	55
2023	56
2024-28	$ 285

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
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	$ 1,000,000

Related-Party Transactions (Nar

Related-Party Transactions (Narrative) (Details) - USD ($)	Feb. 18, 2020	Mar. 08, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Revenue				$ 4,347,000,000	$ 4,101,000,000	$ 3,958,000,000
Members contribution				1,978,000,000	284,000,000
Wholesale transmission service				1,005,000,000	$ 962,000,000	929,000,000
Sponsor Group [Member]
Related Party Transaction [Line Items]
Equity in existing vendor		16.00%
Subsequent Event [Member]
Related Party Transaction [Line Items]
Members contribution	$ 87,000,000
Sempra Texas Holdings [Member]
Related Party Transaction [Line Items]
Cash payments to vendors				$ 109,000
Sponsor Group [Member]
Related Party Transaction [Line Items]
Cash payments to vendors		$ 35,000,000				219,000,000
Sponsor Group [Member] | Capitalized [Member]
Related Party Transaction [Line Items]
Cash payments to vendors		33,000,000				210,000,000
Sponsor Group [Member] | Operating And Maintenance Expense [Member]
Related Party Transaction [Line Items]
Cash payments to vendors		$ 2,000,000				$ 9,000,000
Sharyland Distribution & Transmission Services (SDTS) [Member]
Related Party Transaction [Line Items]
Wholesale transmission service			$ 303,000
Cash payments to vendors			$ 9,000,000

Related-Party Transactions (Sch

Related-Party Transactions (Schedule Of Trade Accounts And Other Receivables From Related Parties) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Texas margin taxes payable	$ 22	$ 26
Net payable (receivable)	19	26
Texas [Member]
Related Party Transaction [Line Items]
Texas margin taxes payable	22	21
Federal [Member]
Related Party Transaction [Line Items]
Federal income taxes payable (receivable)	(3)	5
EFH Corp [Member]
Related Party Transaction [Line Items]
Net payable (receivable)	20	25
EFH Corp [Member] | Texas [Member]
Related Party Transaction [Line Items]
Texas margin taxes payable	22	21
EFH Corp [Member] | Federal [Member]
Related Party Transaction [Line Items]
Federal income taxes payable (receivable)	(2)	4
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 Related Party Transactions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Federal income taxes	$ 56	$ 50	$ (114)
Texas margin taxes	22	21	20
Total payments (receipts)	78	71	(94)
Sempra Texas Holdings [Member]
Related Party Transaction [Line Items]
Federal income taxes	45	59
Texas margin taxes	22	21
Total payments (receipts)	67	80
EFH Corp [Member]
Related Party Transaction [Line Items]
Federal income taxes		(19)	(102)
Texas margin taxes			20
Total payments (receipts)		(19)	(82)
Texas Transmission and Investment LLC [Member]
Related Party Transaction [Line Items]
Federal income taxes	11	10	(12)
Total payments (receipts)	$ 11	$ 10	$ (12)

Supplementary Financial Infor_3

Supplementary Financial Information (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Line Items]
Face value of life insurance policies	$ 172	$ 157
Net cash surrender values	$ 95	$ 87
Depreciation expense as percentage of average depreciable property	2.70%	2.80%	3.40%
Aggregate amortization expenses	$ 52	$ 50	$ 57
Goodwill	$ 4,740	$ 4,064
Trade Accounts Receivable [Member] | Nonaffiliated REP [Member]
Supplemental Financial Information [Line Items]
Concentration risk percentage	15.00%	13.00%
Trade Accounts Receivable [Member] | Second Nonaffiliated REP [Member]
Supplemental Financial Information [Line Items]
Concentration risk percentage	11.00%	10.00%
Land Easements [Member]
Supplemental Financial Information [Line Items]
Weighted average remaining useful life	83 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, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Professional fees	$ 10	$ 12	$ 15
Sempra Acquisition related costs		12
InfraREIT Acquisition related costs	9
Recoverable pension and OPEB - non-service costs	57	53	31
Non-recoverable pension and OPEB (Note 10)	4	6	5
AFUDC equity income	(10)
Interest income	(5)	(1)	(6)
Other		2	1
Other	(2)
Total other deductions and (income) - net	$ 63	$ 84	$ 46

Supplementary Financial Infor_5

Supplementary Financial Information (Schedule Of Interest Expense And Related Charges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Interest	$ 382	$ 358	$ 351
Amortization of debt issuance costs and discounts	9	6	3
Less AFUDC – capitalized interest portion	(16)	(13)	(12)
Total interest expense and related charges	$ 375	$ 351	$ 342

Supplementary Financial Infor_6

Supplementary Financial Information (Schedule Of Trade Accounts And Other Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Gross trade accounts and other receivables	$ 666	$ 562
Allowance for uncollectible accounts	(5)	(3)
Trade accounts receivable - net	$ 661	$ 559

Supplementary Financial Infor_7

Supplementary Financial Information (Summary of Investments And Other Property) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Assets related to employee benefit plans	$ 119	$ 108
Land	12	12
Other	2
Total investments and other property	$ 133	$ 120

Supplementary Financial Infor_8

Supplementary Financial Information (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant and Equipment [Line Items]
Total assets in service	$ 26,749	$ 23,170
Less accumulated depreciation and amortization	7,986	7,513
Net of accumulated depreciation and amortization	18,763	15,657
Construction work in progress	585	417
Held for future use	22	16
Property, plant and equipment - net	19,370	16,090
Distribution [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 14,007	13,105
Composite depreciation rate	2.80%
Avg. life	35 years 9 months 18 days
Transmission [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 11,094	8,568
Composite depreciation rate	2.90%
Avg. life	35 years
Other Assets [Member]
Property Plant and Equipment [Line Items]
Total assets in service	$ 1,648	$ 1,497
Composite depreciation rate	6.90%
Avg. life	14 years 6 months

Supplementary Financial Infor_9

Supplementary Financial Information (Schedule Of Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,508	$ 1,251
Accumulated Amortization	537	486
Net	971	765
Land Easements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	575	464
Accumulated Amortization	107	101
Net	468	363
Capitalized Software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	933	787
Accumulated Amortization	430	385
Net	$ 503	$ 402

Supplementary Financial Info_10

Supplementary Financial Information (Schedule Of Estimated Aggregate Amortization Expenses) (Details) $ in Millions	Dec. 31, 2019USD ($)
Supplementary Financial Information [Abstract]
2020	$ 61
2021	61
2022	61
2023	61
2024	$ 60

Supplementary Financial Info_11

Supplementary Financial Information (Schedule Of Employee Benefit Obligations And Other) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Supplementary Financial Information [Abstract]
Retirement plans and other employee benefits	$ 1,834	$ 1,858
Operating lease liabilities (Notes 1 and 8)	66
Investment tax credits	6	8
Other	74	77
Total employee benefit obligations and other	$ 1,980	$ 1,943

Supplementary Financial Info_12

Supplementary Financial Information (Schedule Of Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Interest	$ 368	$ 368	$ 345
Less capitalized interest	(16)	(13)	(12)
Interest payments (net of amounts capitalized)	352	355	333
Federal	56	50	(114)
State	22	21	20
Total payments (refunds) in lieu of income taxes	78	71	(94)
Noncash increase in operating lease obligations for ROU assets	38
Noncash Sharyland Asset Exchange costs			383
Assets acquired	2,547
Liabilities assumed	(1,223)
Cash paid	1,324
Noncash construction expenditures	$ 278	$ 174	$ 129

Supplementary Financial Info_13

Supplementary Financial Information (Schedule Of Quarterly Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary Financial Information [Abstract]
Operating revenues (Note 4)	$ 1,079	$ 1,211	$ 1,041	$ 1,016	$ 995	$ 1,095	$ 1,021	$ 990
Operating income	236	369	253	216	206	293	244	202	$ 1,074	$ 945	$ 808
Net income	$ 133	$ 263	$ 139	$ 116	$ 119	$ 194	$ 143	$ 89	$ 651	$ 545	$ 419

EFH Bankruptcy Proceedings an_2

EFH Bankruptcy Proceedings and Sempra Acquisition (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 09, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2022
Bankruptcy [Line Items]
Cash paid		$ 1,324		$ 25
Regulatory capitalization ratio, debt		57.50%	60.00%
Regulatory capitalization ratio, equity		42.50%	40.00%
Sempra Energy [Member] | Scenario, Forecast [Member]
Bankruptcy [Line Items]
Minimum aggregate capital expenditures					$ 7,500
Oncor | Sempra Energy [Member]
Bankruptcy [Line Items]
Cash paid	$ 9,450
Oncor | Oncor Holdings [Member]
Bankruptcy [Line Items]
Ownership interests acquired	0.22%
Cash paid	$ 26
Price per interest	$ 18.60
Oncor Holdings [Member] | Sempra Energy [Member]
Bankruptcy [Line Items]
Ownership interests acquired		51.00%
Texas Transmission [Member]
Bankruptcy [Line Items]
Percentage of membership interest owned by non-controlling owners		19.75%