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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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- Definition

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
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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- Definition

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

No definition available.

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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.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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Business Segments (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
Business Segments (Narrative) (Details) $ in Millions	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Pretax loss on disposal	$ (10)	$ (6)	$ 87	$ (24)
Operation, maintenance and other	1,584	1,476	4,592	4,385
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Pretax loss on disposal		(1)	106	(1)
Operation, maintenance and other	$ 76	$ 125	$ 337	$ 388
Number of reportable segments \| segment			2
Beckjord [Member]
Segment Reporting Information [Line Items]
Pretax loss on disposal			$ 106
Operation, maintenance and other			$ 1
National Methanol Company [Member]
Segment Reporting Information [Line Items]
Ownership percentage	17.50%		17.50%