Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Maximum years of participation		35 years
Matching contribution percentage		100.00%
Eligible pay percentage		6.00%
Additional savings plan account contribution percentage for employees not participating in defined pension plans		4.00%
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 11	$ 143
Duke Energy Carolinas [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		42
Progress Energy [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		42
Duke Energy Progress [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		21
Duke Energy Florida [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		21
Duke Energy Ohio [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 3	4
Duke Energy Indiana [Member] \| Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 9

Defined Benefit Plan, Maximum years of participation

No definition available.

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- Definition

Percentage of eligible pay per period contributed to an employee's 401(k) account in lieu of participation in Duke Energy's defined pension plans.

+ References

No definition available.

+ Details

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

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- Definition

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.

+ Details

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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