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Employee Benefit Plans (Projected Benefit Obligations Reconciliation of Funded Status to Net Amount Recognized) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Pension Plan |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | $ 77 | $ 141 | $ 19
Pension Plan | Duke Energy Carolinas |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 7 | 46 | 0
Pension Plan | Progress Energy |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 57 | 45 | 0
Pension Plan | Duke Energy Progress |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 4 | 25 | 0
Pension Plan | Duke Energy Florida |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 53 | 20 | 0
Pension Plan | Duke Energy Ohio |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 2 | 0 | 4
Pension Plan | Duke Energy Indiana |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 2 | 8 | 0
Pension Plan | Piedmont |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 1 | 0 | 11
Pension Plan | Qualified Plan |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 7,869 | 8,448 |
Service cost | 150 | 174 | 159
Interest cost | 317 | 299 | 328
Actuarial loss (gain) | 716 | (485) |
Transfers | 0 | 0 |
Benefits paid | (731) | (567) |
Obligation at measurement date | 8,321 | 7,869 | 8,448
Accumulated Benefit Obligation at measurement date | 8,262 | 7,818 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 8,233 | 9,003 |
Employer contributions | 77 | 141 |
Actual return on plan assets | 1,331 | (344) |
Benefits paid | (731) | (567) |
Transfers | 0 | 0 |
Plan assets at measurement date | 8,910 | 8,233 | 9,003
Funded status of plan | 589 | 364 |
Pension Plan | Qualified Plan | Duke Energy Carolinas |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,954 | 2,029 |
Service cost | 47 | 56 | 48
Interest cost | 75 | 72 | 79
Actuarial loss (gain) | 101 | (44) |
Transfers | 11 | 0 |
Benefits paid | (265) | (159) |
Obligation at measurement date | 1,923 | 1,954 | 2,029
Accumulated Benefit Obligation at measurement date | 1,923 | 1,954 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 2,168 | 2,372 |
Employer contributions | 7 | 46 |
Actual return on plan assets | 342 | (91) |
Benefits paid | (265) | (159) |
Transfers | 11 | 0 |
Plan assets at measurement date | 2,263 | 2,168 | 2,372
Funded status of plan | 340 | 214 |
Pension Plan | Qualified Plan | Progress Energy |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 2,433 | 2,637 |
Service cost | 43 | 49 | 45
Interest cost | 100 | 94 | 100
Actuarial loss (gain) | 223 | (204) |
Transfers | 0 | 0 |
Benefits paid | (191) | (143) |
Obligation at measurement date | 2,608 | 2,433 | 2,637
Accumulated Benefit Obligation at measurement date | 2,578 | 2,404 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 2,606 | 2,814 |
Employer contributions | 57 | 45 |
Actual return on plan assets | 426 | (110) |
Benefits paid | (191) | (143) |
Transfers | 0 | 0 |
Plan assets at measurement date | 2,898 | 2,606 | 2,814
Funded status of plan | 290 | 173 |
Pension Plan | Qualified Plan | Duke Energy Progress |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,125 | 1,211 |
Service cost | 25 | 28 | 26
Interest cost | 45 | 43 | 47
Actuarial loss (gain) | 87 | (87) |
Transfers | 0 | 0 |
Benefits paid | (112) | (70) |
Obligation at measurement date | 1,170 | 1,125 | 1,211
Accumulated Benefit Obligation at measurement date | 1,170 | 1,125 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 1,268 | 1,366 |
Employer contributions | 4 | 25 |
Actual return on plan assets | 204 | (53) |
Benefits paid | (112) | (70) |
Transfers | 0 | 0 |
Plan assets at measurement date | 1,364 | 1,268 | 1,366
Funded status of plan | 194 | 143 |
Pension Plan | Qualified Plan | Duke Energy Florida |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,295 | 1,410 |
Service cost | 18 | 21 | 19
Interest cost | 54 | 50 | 53
Actuarial loss (gain) | 135 | (114) |
Transfers | 0 | 0 |
Benefits paid | (78) | (72) |
Obligation at measurement date | 1,424 | 1,295 | 1,410
Accumulated Benefit Obligation at measurement date | 1,392 | 1,265 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 1,322 | 1,429 |
Employer contributions | 53 | 20 |
Actual return on plan assets | 218 | (55) |
Benefits paid | (78) | (72) |
Transfers | 0 | 0 |
Plan assets at measurement date | 1,515 | 1,322 | 1,429
Funded status of plan | 91 | 27 |
Pension Plan | Qualified Plan | Duke Energy Ohio |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 435 | 479 |
Service cost | 4 | 5 | 4
Interest cost | 18 | 17 | 18
Actuarial loss (gain) | 54 | (29) |
Transfers | 0 | 0 |
Benefits paid | (30) | (37) |
Obligation at measurement date | 481 | 435 | 479
Accumulated Benefit Obligation at measurement date | 471 | 425 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 405 | 458 |
Employer contributions | 2 | 0 |
Actual return on plan assets | 66 | (16) |
Benefits paid | (30) | (37) |
Transfers | 0 | 0 |
Plan assets at measurement date | 443 | 405 | 458
Funded status of plan | (38) | (30) |
Pension Plan | Qualified Plan | Duke Energy Indiana |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 618 | 669 |
Service cost | 8 | 10 | 9
Interest cost | 26 | 23 | 26
Actuarial loss (gain) | 87 | (29) |
Transfers | 0 | 0 |
Benefits paid | (46) | (55) |
Obligation at measurement date | 693 | 618 | 669
Accumulated Benefit Obligation at measurement date | 686 | 614 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 611 | 684 |
Employer contributions | 2 | 8 |
Actual return on plan assets | 100 | (26) |
Benefits paid | (46) | (55) |
Transfers | 0 | 0 |
Plan assets at measurement date | 667 | 611 | 684
Funded status of plan | (26) | (7) |
Pension Plan | Qualified Plan | Piedmont |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 264 | 313 |
Service cost | 5 | 7 | 10
Interest cost | 10 | 11 | 14
Actuarial loss (gain) | 33 | (18) |
Transfers | 0 | (16) |
Benefits paid | (20) | (33) |
Obligation at measurement date | 292 | 264 | 313
Accumulated Benefit Obligation at measurement date | 292 | 264 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 305 | 368 |
Employer contributions | 1 | 0 |
Actual return on plan assets | 49 | (14) |
Benefits paid | (20) | (33) |
Transfers | 0 | (16) |
Plan assets at measurement date | 335 | 305 | 368
Funded status of plan | 43 | 41 |
Other Post-Retirement Benefit Plans |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 728 | 813 |
Service cost | 4 | 6 | 4
Interest cost | 30 | 28 | 34
Plan participants' contributions | 16 | 18 |
Actuarial loss (gain) | 28 | (51) |
Transfers | 0 | 0 |
Benefits paid | (83) | (86) |
Obligation at measurement date | 723 | 728 | 813
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 195 | 225 |
Employer contributions | 60 |  |
Actual return on plan assets | 32 | (8) |
Benefits paid | (83) | (86) |
Employer contributions (reimbursements) |  | 46 |
Plan participants' contributions | 16 | 18 |
Plan assets at measurement date | 220 | 195 | 225
Funded status of plan | (503) | (533) |
Other Post-Retirement Benefit Plans | Duke Energy Carolinas |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 174 | 189 |
Service cost | 1 | 1 | 1
Interest cost | 7 | 7 | 8
Plan participants' contributions | 3 | 3 |
Actuarial loss (gain) | 9 | (8) |
Transfers | 0 | 0 |
Benefits paid | (19) | (18) |
Obligation at measurement date | 175 | 174 | 189
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 115 | 133 |
Employer contributions | 11 |  |
Actual return on plan assets | 20 | (5) |
Benefits paid | (19) | (18) |
Employer contributions (reimbursements) |  | 2 |
Plan participants' contributions | 3 | 3 |
Plan assets at measurement date | 130 | 115 | 133
Funded status of plan | (45) | (59) |
Other Post-Retirement Benefit Plans | Progress Energy |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 303 | 342 |
Service cost | 1 | 1 | 0
Interest cost | 12 | 12 | 13
Plan participants' contributions | 6 | 6 |
Actuarial loss (gain) | 13 | (23) |
Transfers | 0 | 0 |
Benefits paid | (32) | (35) |
Obligation at measurement date | 303 | 303 | 342
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 0 | 0 |
Employer contributions | 26 |  |
Actual return on plan assets | (1) | 0 |
Benefits paid | (32) | (35) |
Employer contributions (reimbursements) |  | 29 |
Plan participants' contributions | 6 | 6 |
Plan assets at measurement date | (1) | 0 | 0
Funded status of plan | (304) | (303) |
Other Post-Retirement Benefit Plans | Duke Energy Progress |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 166 | 184 |
Service cost | 0 | 0 | 0
Interest cost | 7 | 6 | 7
Plan participants' contributions | 3 | 4 |
Actuarial loss (gain) | 9 | (9) |
Transfers | 0 | 0 |
Benefits paid | (17) | (19) |
Obligation at measurement date | 168 | 166 | 184
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 0 | 0 |
Employer contributions | 13 |  |
Actual return on plan assets | 0 | 0 |
Benefits paid | (17) | (19) |
Employer contributions (reimbursements) |  | 15 |
Plan participants' contributions | 3 | 4 |
Plan assets at measurement date | (1) | 0 | 0
Funded status of plan | (169) | (166) |
Other Post-Retirement Benefit Plans | Duke Energy Florida |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 137 | 156 |
Service cost | 1 | 1 | 0
Interest cost | 5 | 6 | 6
Plan participants' contributions | 2 | 3 |
Actuarial loss (gain) | 5 | (13) |
Transfers | 0 | 0 |
Benefits paid | (15) | (16) |
Obligation at measurement date | 135 | 137 | 156
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 0 | 0 |
Employer contributions | 13 |  |
Actual return on plan assets | 0 | 0 |
Benefits paid | (15) | (16) |
Employer contributions (reimbursements) |  | 13 |
Plan participants' contributions | 2 | 3 |
Plan assets at measurement date | 0 | 0 | 0
Funded status of plan | (135) | (137) |
Other Post-Retirement Benefit Plans | Duke Energy Ohio |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 29 | 30 |
Service cost | 0 | 1 | 0
Interest cost | 1 | 1 | 1
Plan participants' contributions | 1 | 1 |
Actuarial loss (gain) | 1 | (2) |
Transfers | 0 | 0 |
Benefits paid | (3) | (2) |
Obligation at measurement date | 29 | 29 | 30
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 8 | 7 |
Employer contributions | 2 |  |
Actual return on plan assets | 1 | 0 |
Benefits paid | (3) | (2) |
Employer contributions (reimbursements) |  | 2 |
Plan participants' contributions | 1 | 1 |
Plan assets at measurement date | 9 | 8 | 7
Funded status of plan | (20) | (21) |
Other Post-Retirement Benefit Plans | Duke Energy Indiana |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 67 | 78 |
Service cost | 1 | 1 | 0
Interest cost | 3 | 3 | 3
Plan participants' contributions | 2 | 2 |
Actuarial loss (gain) | 2 | (5) |
Transfers | 0 | 0 |
Benefits paid | (11) | (12) |
Obligation at measurement date | 64 | 67 | 78
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 5 | 11 |
Employer contributions | 9 |  |
Actual return on plan assets | 0 | 0 |
Benefits paid | (11) | (12) |
Employer contributions (reimbursements) |  | 4 |
Plan participants' contributions | 2 | 2 |
Plan assets at measurement date | 5 | 5 | 11
Funded status of plan | (59) | (62) |
Other Post-Retirement Benefit Plans | Piedmont |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 30 | 32 |
Service cost | 0 | 1 | 1
Interest cost | 1 | 1 | 1
Plan participants' contributions | 0 | 0 |
Actuarial loss (gain) | 0 | (1) |
Transfers | 0 | (1) |
Benefits paid | (1) | (2) |
Obligation at measurement date | 30 | 30 | 32
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 29 | 31 |
Employer contributions | 0 |  |
Actual return on plan assets | 6 | (1) |
Benefits paid | (1) | (2) |
Employer contributions (reimbursements) |  | 1 |
Plan participants' contributions | 0 | 0 |
Plan assets at measurement date | 34 | 29 | $ 31
Funded status of plan | $ 4 | $ (1) |

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- Definition Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 + Details
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- Definition Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(6) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 + Details
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