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Employee Benefit Plans (Employee Savings Plans) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Employee Savings Plans [Abstract] |  |  |
Matching contribution percentage | 100.00% |  |
Eligible pay percentage | 6.00% |  |
Additional contribution percentage for employees not participating in defined pension plans | 4.00% |  |
Employer contributions | $ 214 | $ 213 | $ 179
Duke Energy Carolinas |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 66 | 68 | 61
Progress Energy |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 58 | 58 | 53
Duke Energy Progress |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 38 | 40 | 37
Duke Energy Florida |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 20 | 19 | 16
Duke Energy Ohio |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 5 | 4 | 3
Duke Energy Indiana |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | 11 | 10 | 9
Piedmont |  |  |
Employee Savings Plans [Abstract] |  |  |
Employer contributions | $ 13 | $ 12 | $ 7
Minimum | Piedmont |  |  |
Employee Savings Plans [Abstract] |  |  |
Additional contribution percentage for employees not participating in defined pension plans | 3.00% |  |
Maximum | Piedmont |  |  |
Employee Savings Plans [Abstract] |  |  |
Additional contribution percentage for employees not participating in defined pension plans | 5.00% |  |

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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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- References No definition available. + Details
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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 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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