Goodwill (Goodwill By Reportable Operating Segment) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2012	Dec. 31, 2011
Goodwill	$ 4,720	$ 4,720
Goodwill accumulated impairment charges	(871)	(871)
Foreign Exchange and Other Changes	(7)
Goodwill as adjusted for accumulated impairment charges	3,842	3,849
Duke Energy Ohio [Member]
Goodwill	2,325	2,325
Goodwill accumulated impairment charges	(1,404)	(1,404)
Goodwill as adjusted for accumulated impairment charges	921	921
USFE&G [Member]
Goodwill	3,483	3,483
Goodwill as adjusted for accumulated impairment charges	3,483	3,483
Commercial Power [Member]
Goodwill	940	940
Goodwill accumulated impairment charges	(871)	(871)
Goodwill as adjusted for accumulated impairment charges	69	69
International [Member]
Goodwill	297	297
Foreign Exchange and Other Changes	(7)
Goodwill as adjusted for accumulated impairment charges	290	297
Franchised Electric & Gas [Member] \| Duke Energy Ohio [Member]
Goodwill	1,137	1,137
Goodwill accumulated impairment charges	(216)	(216)
Goodwill as adjusted for accumulated impairment charges	921	921
DEO Commercial Power [Member] \| Duke Energy Ohio [Member]
Goodwill	1,188	1,188
Goodwill accumulated impairment charges	(1,188)	(1,188)
Goodwill as adjusted for accumulated impairment charges	$ 0	$ 0

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

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-Number 141R

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

The increase (decrease) in the recorded value of goodwill for foreign currency translation adjustments and purchase accounting adjustments needed to revise the carrying amount of goodwill to fair value.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Subparagraph e

-Paragraph 45

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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+ Details