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Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Maximum years of participation | 35 years |  |  |
Impact of plan conversion on next year's net periodic benefit cost | $ 33 |  |  |
Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target allocation | 100.00% |  |  |
Expected long-term rate of return on plan assets | 6.85% |  |  |
Fair value of securities on loan | $ 351 | $ 154 |  |
Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 77 | 141 | $ 19 |
Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 12 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 8,321 | 7,869 | $ 8,448 |
Accumulated Benefit Obligation at measurement date | $ 8,262 | $ 7,818 |  |
Expected long-term rate of return on plan assets | 6.85% | 6.50% | 6.75% |
Employer contributions | $ 77 | $ 141 |  |
Benefits paid | 731 | 567 |  |
Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 318 |  |  |
Accumulated Benefit Obligation at measurement date | 318 |  |  |
Employer contributions | 25 |  |  |
Benefits paid | $ 25 |  |  |
Pension Plan | Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Master trust allocation percentage | 98.00% |  |  |
Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 8 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 723 | $ 728 | $ 813 |
Expected long-term rate of return on plan assets | 6.85% | 6.50% | 6.50% |
Employer contributions | $ 60 |  |  |
Benefits paid | $ 83 | $ 86 |  |
Other Post-Retirement Benefit Plans | Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Master trust allocation percentage | 2.00% |  |  |
Duke Energy Carolinas | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 7 | 46 | $ 0 |
Duke Energy Carolinas | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 12 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 1,923 | 1,954 | 2,029 |
Accumulated Benefit Obligation at measurement date | 1,923 | 1,954 |  |
Employer contributions | 7 | 46 |  |
Benefits paid | 265 | 159 |  |
Duke Energy Carolinas | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 15 |  |  |
Accumulated Benefit Obligation at measurement date | 15 |  |  |
Employer contributions | 2 |  |  |
Benefits paid | $ 2 |  |  |
Duke Energy Carolinas | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 8 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 175 | 174 | 189 |
Employer contributions | 11 |  |  |
Benefits paid | 19 | 18 |  |
Progress Energy | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 57 | 45 | 0 |
Progress Energy | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 12 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 2,608 | 2,433 | 2,637 |
Accumulated Benefit Obligation at measurement date | 2,578 | 2,404 |  |
Employer contributions | 57 | 45 |  |
Benefits paid | 191 | 143 |  |
Progress Energy | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 110 |  |  |
Accumulated Benefit Obligation at measurement date | 110 |  |  |
Employer contributions | 9 |  |  |
Benefits paid | $ 9 |  |  |
Progress Energy | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 6 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 303 | 303 | 342 |
Employer contributions | 26 |  |  |
Benefits paid | 32 | 35 |  |
Duke Energy Progress | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 4 | 25 | 0 |
Duke Energy Progress | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 13 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 1,170 | 1,125 | 1,211 |
Accumulated Benefit Obligation at measurement date | 1,170 | 1,125 |  |
Employer contributions | 4 | 25 |  |
Benefits paid | 112 | 70 |  |
Duke Energy Progress | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 32 |  |  |
Accumulated Benefit Obligation at measurement date | 32 |  |  |
Employer contributions | 3 |  |  |
Duke Energy Progress | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 168 | 166 | 184 |
Employer contributions | 13 |  |  |
Benefits paid | 17 | 19 |  |
Duke Energy Florida | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 53 | 20 | 0 |
Duke Energy Florida | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 12 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 1,424 | 1,295 | 1,410 |
Accumulated Benefit Obligation at measurement date | 1,392 | 1,265 |  |
Employer contributions | 53 | 20 |  |
Benefits paid | 78 | 72 |  |
Duke Energy Florida | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 45 |  |  |
Accumulated Benefit Obligation at measurement date | 45 |  |  |
Employer contributions | 3 |  |  |
Benefits paid | $ 3 |  |  |
Duke Energy Florida | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 7 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 135 | 137 | 156 |
Employer contributions | 13 |  |  |
Benefits paid | 15 | 16 |  |
Duke Energy Ohio | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 2 | 0 | 4 |
Duke Energy Ohio | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 13 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 481 | 435 | 479 |
Accumulated Benefit Obligation at measurement date | 471 | 425 |  |
Employer contributions | 2 | 0 |  |
Benefits paid | 30 | 37 |  |
Duke Energy Ohio | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 4 |  |  |
Accumulated Benefit Obligation at measurement date | 4 |  |  |
Benefits paid | $ 3 |  |  |
Duke Energy Ohio | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 7 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 29 | 29 | 30 |
Employer contributions | 2 |  |  |
Benefits paid | 3 | 2 |  |
Duke Energy Indiana | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 2 | 8 | 0 |
Duke Energy Indiana | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 13 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 693 | 618 | 669 |
Accumulated Benefit Obligation at measurement date | 686 | 614 |  |
Employer contributions | 2 | 8 |  |
Benefits paid | 46 | 55 |  |
Duke Energy Indiana | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 3 |  |  |
Accumulated Benefit Obligation at measurement date | $ 3 |  |  |
Duke Energy Indiana | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 6 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 64 | 67 | 78 |
Employer contributions | 9 |  |  |
Benefits paid | $ 11 | 12 |  |
Piedmont |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Vesting period | 3 years |  |  |
Term | 3 years |  |  |
Piedmont | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 1 | 0 | 11 |
Piedmont | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 9 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 292 | 264 | 313 |
Accumulated Benefit Obligation at measurement date | 292 | 264 |  |
Employer contributions | 1 | 0 |  |
Benefits paid | 20 | 33 |  |
Piedmont | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 4 |  |  |
Accumulated Benefit Obligation at measurement date | $ 4 |  |  |
Piedmont | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 6 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 30 | 30 | $ 32 |
Employer contributions | 0 |  |  |
Benefits paid | 1 | $ 2 |  |
Liability Hedging Assets | Pension Plan | Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target allocation |  |  |  | 58.00%
Return Seeking Assets | Pension Plan | Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target allocation |  |  |  | 42.00%
Minimum | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected long-term rate of return on plan assets |  |  | 6.50% |
Retirement plan settled |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 94 |  |  |
Retirement plan settled | Duke Energy Carolinas |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 53 |  |  |
Retirement plan settled | Progress Energy |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 26 |  |  |
Retirement plan settled | Duke Energy Progress |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 20 |  |  |
Retirement plan settled | Duke Energy Florida |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 6 |  |  |
Retirement plan settled | Duke Energy Ohio |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 2 |  |  |
Retirement plan settled | Duke Energy Indiana |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | 4 |  |  |
Retirement plan settled | Piedmont |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Settlement charges | $ 8 |  |  |

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