Commitments and Contingencies, Environmental Contingencies (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)
Harrington Units 1 and 2 \| Implementation of the National Ambient Air Quality Standard for Sulfur Dioxide
Environmental Requirements [Abstract]
Number of Years Unclassifiable Areas Will Be Monitored	3 years
Tolk Units 1 and 2 \| Capital Commitments \| Regional Haze Rules
Environmental Requirements [Abstract]
Liability for Estimated Cost to Comply with Regulation	$ 600

Estimated undiscounted amount of the accrual required to comply with required regulation.

No definition available.

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Balance Type:	credit
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