Goodwill (Schedule of Future Amortization Expense)(Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
2013	$ 45
2014	19
2015	17
2016	16
2017	15
Duke Energy Ohio [Member]
Finite-Lived Intangible Assets [Line Items]
2013	8
2014	13
2015	10
2016	10
2017	9
Duke Energy Indiana [Member]
Finite-Lived Intangible Assets [Line Items]
2013	30
2014	1
2015	1
2016	1
2017	$ 1

Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

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Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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