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Employee Benefit Plans (Employee Savings Plans) (Details) - Employee Savings Plan [Member] - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 48 | $ 39 | $ 118 | $ 104
Duke Energy Carolinas [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 15 | 13 | 38 | 35
Progress Energy [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 13 | 12 | 32 | 30
Duke Energy Progress [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 9 | 8 | 22 | 21
Duke Energy Florida [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 4 | 4 | 10 | 9
Duke Energy Ohio [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 1 | 1 | 2 | 2
Duke Energy Indiana [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | 2 | 2 | 5 | 5
Piedmont Natural Gas [Member] |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 2 | $ 1 | $ 6 | $ 3

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + 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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- Details
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- Details
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- Details
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