2017 Asset Exchange Transaction - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Nonmonetary Transaction [Line Items]
Proceeds from asset exchange transaction	$ 1,632
Sharyland Distribution & Transmission Services, L.L.C. \| 2017 Asset Exchange Agreement \| Oncor Electric Delivery Company LLC
Nonmonetary Transaction [Line Items]
Net assets exchanged		$ 403,000
Transmission assets		383,000
Proceeds from asset exchange transaction		18,000
Gain on asset exchange transaction		300
Sharyland Distribution & Transmission Services, L.L.C. \| 2017 Asset Exchange Agreement \| Oncor Electric Delivery Company LLC \| Prepaids and Other Current Assets
Nonmonetary Transaction [Line Items]
Receivable under asset exchange transaction		$ 2,000

Gain (loss) on asset exchange transaction.

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- Definition

Public utilities property plant and equipment net plant assets transferred.

+ References

No definition available.

+ Details

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- Definition

Public utilities property plant and equipment receivable under asset exchange transaction.

+ References

No definition available.

+ Details

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- Definition

Public utilities property plant and equipment transmission net.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

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