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Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Maximum years of participation | 35 years |  |  |
Vesting period | 3 years |  |  |
Master Trust |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target allocation | 100.00% |  |  |
Expected long-term rate of return on plan assets | 6.50% |  |  |
Fair value of securities on loan | $ 482 | $ 351 |  |
Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 77 | $ 141 |
Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 13 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 8,634 | 8,321 | $ 7,869 |
Accumulated Benefit Obligation at measurement date | $ 8,577 | $ 8,262 |  |
Expected long-term rate of return on plan assets | 6.85% | 6.85% | 6.50% |
Employer contributions |  | $ 77 |  |
Benefits paid | $ 541 | 731 |  |
Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 320 |  |  |
Accumulated Benefit Obligation at measurement date | 320 |  |  |
Employer contributions | 23 |  |  |
Benefits paid | $ 23 |  |  |
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 | $ 709 | $ 723 | $ 728 |
Expected long-term rate of return on plan assets | 6.85% | 6.85% | 6.50% |
Employer contributions | $ 53 |  |  |
Benefits paid | $ 75 | $ 83 |  |
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 | $ 0 | 7 | $ 46 |
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 | $ 1,988 | 1,923 | 1,954 |
Accumulated Benefit Obligation at measurement date | 1,989 | 1,923 |  |
Employer contributions |  | 7 |  |
Benefits paid | 137 | 265 |  |
Duke Energy Carolinas | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 13 |  |  |
Accumulated Benefit Obligation at measurement date | 13 |  |  |
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 | $ 174 | 175 | 174 |
Employer contributions | 10 |  |  |
Benefits paid | 18 | 19 |  |
Progress Energy | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 57 | 45 |
Progress Energy | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 14 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 2,715 | 2,608 | 2,433 |
Accumulated Benefit Obligation at measurement date | 2,684 | 2,578 |  |
Employer contributions |  | 57 |  |
Benefits paid | 160 | 191 |  |
Progress Energy | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 111 |  |  |
Accumulated Benefit Obligation at measurement date | 111 |  |  |
Employer contributions | 8 |  |  |
Benefits paid | $ 8 |  |  |
Progress Energy | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 7 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 299 | 303 | 303 |
Employer contributions | 23 |  |  |
Benefits paid | 28 | 32 |  |
Duke Energy Progress | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 4 | 25 |
Duke Energy Progress | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 14 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 1,193 | 1,170 | 1,125 |
Accumulated Benefit Obligation at measurement date | 1,194 | 1,170 |  |
Employer contributions |  | 4 |  |
Benefits paid | 83 | 112 |  |
Duke Energy Progress | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 33 |  |  |
Accumulated Benefit Obligation at measurement date | 33 |  |  |
Employer contributions | 3 |  |  |
Benefits paid | $ 3 |  |  |
Duke Energy Progress | Other Post-Retirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 6 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 166 | 168 | 166 |
Employer contributions | 11 |  |  |
Benefits paid | 15 | 17 |  |
Duke Energy Florida | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 53 | 20 |
Duke Energy Florida | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 14 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 1,507 | 1,424 | 1,295 |
Accumulated Benefit Obligation at measurement date | 1,476 | 1,392 |  |
Employer contributions |  | 53 |  |
Benefits paid | 76 | 78 |  |
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 | $ 130 | 135 | 137 |
Employer contributions | 10 |  |  |
Benefits paid | 13 | 15 |  |
Duke Energy Ohio | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 2 | 0 |
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 | $ 502 | 481 | 435 |
Accumulated Benefit Obligation at measurement date | 493 | 471 |  |
Employer contributions |  | 2 |  |
Benefits paid | 34 | 30 |  |
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 |  |  |
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 | $ 27 | 29 | 29 |
Employer contributions | 3 |  |  |
Benefits paid | 4 | 3 |  |
Duke Energy Indiana | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 2 | 8 |
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 | $ 715 | 693 | 618 |
Accumulated Benefit Obligation at measurement date | 709 | 686 |  |
Employer contributions |  | 2 |  |
Benefits paid | 49 | 46 |  |
Duke Energy Indiana | Pension Plan | Nonqualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Benefit Obligation | 2 |  |  |
Accumulated Benefit Obligation at measurement date | $ 2 |  |  |
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 | $ 61 | 64 | 67 |
Employer contributions | 8 |  |  |
Benefits paid | $ 9 | 11 |  |
Piedmont |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Term | 3 years |  |  |
Piedmont | Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer contributions | $ 0 | 1 | 0 |
Piedmont | Pension Plan | Qualified Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Average remaining service period, in years | 9 years |  |  |
Defined Benefit Plan, Benefit Obligation | $ 293 | 292 | 264 |
Accumulated Benefit Obligation at measurement date | 294 | 292 |  |
Employer contributions |  | 1 |  |
Benefits paid | 27 | 20 |  |
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 | $ 30 |
Employer contributions | 1 |  |  |
Benefits paid | $ 2 | 1 |  |
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 |  |  |  |
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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