The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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-Section 45
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

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The amount of operating expenses for the period that are associated with the utility's normal revenue producing operation; including selling, general, and administrative expenses, costs incurred for routine plant repairs and maintenance, and operations.

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Business Segments (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
Business Segments (Narrative) (Details) $ in Millions	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Gains (Losses) on Sales of Other Assets and Other, net	$ (3)	$ (7)	$ 97	$ (18)
Operation, maintenance and other	1,544	1,441	3,008	2,909
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Gains (Losses) on Sales of Other Assets and Other, net			106
Operation, maintenance and other	$ 130	$ 132	$ 261	$ 263
Number of Reportable Segments \| segment			2
Beckjord [Member]
Segment Reporting Information [Line Items]
Gains (Losses) on Sales of Other Assets and Other, net			$ (106)
Operation, maintenance and other			$ 1
National Methanol Company [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	17.50%		17.50%