Derivative Instruments (Details Textuals) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($) agreement	Dec. 31, 2018 USD ($) agreement
Cash Flow Hedges
Derivative [Line Items]
Unamortized losses associated with prior interest rate hedges	$ 14	$ 15
Gains (losses) to be amortized to interest expenses during next twelve months	$ (2)
Number of outstanding commodity or interest rate derivatives \| agreement	0	0
Fair Value Hedging
Derivative [Line Items]
Number of fixed-for-floating interest rate swap agreements outstanding \| agreement	0	0
Gains included in long-term debt associated with prior fixed-for-floating interest rate swap agreements	$ 2	$ 2
NUGs
Derivative [Line Items]
Liability position	41	44
Settlements	10
Unrealized gain (loss)	(7)
FTRs
Derivative [Line Items]
Settlements	(10)
Net asset position	$ (1)	$ 9

Settled Contracts.

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Derivative instruments not designated as hedging instruments unrealized gain (loss).

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Gains (Losses) To Be Amortized To Interest Expenses During Next Twelve Months.

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Number Of Outstanding Commodity or Interest Rate Derivatives

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Number of Outstanding Fixed-for-Floating Interest Rate Swap Agreements

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Unamortized gains included in long-term debt associated with prior fixed-for-floating interest rate swap agreements.

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Unamortized losses associated with prior interest rate hedges.

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Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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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.

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