Impact of Derivative Activities on Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Fair Value Hedges, Net	$ 0	$ 0	$ 0
Not Designated as Hedging Instrument \| Natural Gas Commodity Contract
Derivative [Line Items]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net	1	1
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)	$ 1	$ 1

Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net

No definition available.

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- Definition

Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)

+ References

No definition available.

+ Details

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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

No definition available.

+ Details

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- Definition

Net fair value of all derivative instruments designated as fair value hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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- Details

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- Details

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