XML 208 R152.htm IDEA: XBRL DOCUMENT
v3.20.4

Employee Benefit Plans (Projected Benefit Obligations Reconciliation of Funded Status to Net Amount Recognized) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Pension Plan |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | $ 0 | $ 77 | $ 141
Pension Plan | Duke Energy Carolinas |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 7 | 46
Pension Plan | Progress Energy |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 57 | 45
Pension Plan | Duke Energy Progress |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 4 | 25
Pension Plan | Duke Energy Florida |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 53 | 20
Pension Plan | Duke Energy Ohio |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 2 | 0
Pension Plan | Duke Energy Indiana |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 2 | 8
Pension Plan | Piedmont |  |  |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Employer contributions | 0 | 1 | 0
Pension Plan | Qualified Plan |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 8,321 | 7,869 |
Service cost | 157 | 150 | 182
Interest cost | 269 | 317 | 299
Actuarial loss | 433 | 716 |
Transfers | 0 | 0 |
Benefits paid | (541) | (731) |
Benefits paid – settlements | (5) |  |
Obligation at measurement date | 8,634 | 8,321 | 7,869
Accumulated Benefit Obligation at measurement date | 8,577 | 8,262 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 8,910 | 8,233 |
Employer contributions |  | 77 |
Actual return on plan assets | 973 | 1,331 |
Benefits paid | (541) | (731) |
Benefits paid – settlements | (5) |  |
Transfers | 0 | 0 |
Plan assets at measurement date | 9,337 | 8,910 | 8,233
Funded status of plan | 703 | 589 |
Pension Plan | Qualified Plan | Duke Energy Carolinas |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,923 | 1,954 |
Service cost | 49 | 47 | 58
Interest cost | 62 | 75 | 72
Actuarial loss | 83 | 101 |
Transfers | 8 | 11 |
Benefits paid | (137) | (265) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 1,988 | 1,923 | 1,954
Accumulated Benefit Obligation at measurement date | 1,989 | 1,923 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 2,263 | 2,168 |
Employer contributions |  | 7 |
Actual return on plan assets | 247 | 342 |
Benefits paid | (137) | (265) |
Benefits paid – settlements | 0 |  |
Transfers | 8 | 11 |
Plan assets at measurement date | 2,381 | 2,263 | 2,168
Funded status of plan | 393 | 340 |
Pension Plan | Qualified Plan | Progress Energy |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 2,608 | 2,433 |
Service cost | 46 | 43 | 51
Interest cost | 85 | 100 | 94
Actuarial loss | 144 | 223 |
Transfers | (8) | 0 |
Benefits paid | (160) | (191) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 2,715 | 2,608 | 2,433
Accumulated Benefit Obligation at measurement date | 2,684 | 2,578 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 2,898 | 2,606 |
Employer contributions |  | 57 |
Actual return on plan assets | 319 | 426 |
Benefits paid | (160) | (191) |
Benefits paid – settlements | 0 |  |
Transfers | (8) | 0 |
Plan assets at measurement date | 3,049 | 2,898 | 2,606
Funded status of plan | 334 | 290 |
Pension Plan | Qualified Plan | Duke Energy Progress |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,170 | 1,125 |
Service cost | 26 | 25 | 29
Interest cost | 38 | 45 | 43
Actuarial loss | 50 | 87 |
Transfers | (8) | 0 |
Benefits paid | (83) | (112) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 1,193 | 1,170 | 1,125
Accumulated Benefit Obligation at measurement date | 1,194 | 1,170 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 1,364 | 1,268 |
Employer contributions |  | 4 |
Actual return on plan assets | 149 | 204 |
Benefits paid | (83) | (112) |
Benefits paid – settlements | 0 |  |
Transfers | (8) | 0 |
Plan assets at measurement date | 1,422 | 1,364 | 1,268
Funded status of plan | 229 | 194 |
Pension Plan | Qualified Plan | Duke Energy Florida |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 1,424 | 1,295 |
Service cost | 20 | 18 | 22
Interest cost | 46 | 54 | 50
Actuarial loss | 93 | 135 |
Transfers | 0 | 0 |
Benefits paid | (76) | (78) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 1,507 | 1,424 | 1,295
Accumulated Benefit Obligation at measurement date | 1,476 | 1,392 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 1,515 | 1,322 |
Employer contributions |  | 53 |
Actual return on plan assets | 166 | 218 |
Benefits paid | (76) | (78) |
Benefits paid – settlements | 0 |  |
Transfers | 0 | 0 |
Plan assets at measurement date | 1,605 | 1,515 | 1,322
Funded status of plan | 98 | 91 |
Pension Plan | Qualified Plan | Duke Energy Ohio |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 481 | 435 |
Service cost | 4 | 4 | 5
Interest cost | 15 | 18 | 17
Actuarial loss | 21 | 54 |
Transfers | 15 | 0 |
Benefits paid | (34) | (30) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 502 | 481 | 435
Accumulated Benefit Obligation at measurement date | 493 | 471 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 443 | 405 |
Employer contributions |  | 2 |
Actual return on plan assets | 48 | 66 |
Benefits paid | (34) | (30) |
Benefits paid – settlements | 0 |  |
Transfers | 15 | 0 |
Plan assets at measurement date | 472 | 443 | 405
Funded status of plan | (30) | (38) |
Pension Plan | Qualified Plan | Duke Energy Indiana |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 693 | 618 |
Service cost | 8 | 8 | 11
Interest cost | 22 | 26 | 23
Actuarial loss | 46 | 87 |
Transfers | 0 | 0 |
Benefits paid | (49) | (46) |
Benefits paid – settlements | (5) |  |
Obligation at measurement date | 715 | 693 | 618
Accumulated Benefit Obligation at measurement date | 709 | 686 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 667 | 611 |
Employer contributions |  | 2 |
Actual return on plan assets | 71 | 100 |
Benefits paid | (49) | (46) |
Benefits paid – settlements | (5) |  |
Transfers | 0 | 0 |
Plan assets at measurement date | 684 | 667 | 611
Funded status of plan | (31) | (26) |
Pension Plan | Qualified Plan | Piedmont |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 292 | 264 |
Service cost | 5 | 5 | 7
Interest cost | 9 | 10 | 11
Actuarial loss | 14 | 33 |
Transfers | 0 | 0 |
Benefits paid | (27) | (20) |
Benefits paid – settlements | 0 |  |
Obligation at measurement date | 293 | 292 | 264
Accumulated Benefit Obligation at measurement date | 294 | 292 |
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 335 | 305 |
Employer contributions |  | 1 |
Actual return on plan assets | 35 | 49 |
Benefits paid | (27) | (20) |
Benefits paid – settlements | 0 |  |
Transfers | 0 | 0 |
Plan assets at measurement date | 343 | 335 | 305
Funded status of plan | 50 | 43 |
Other Post-Retirement Benefit Plans |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 723 | 728 |
Service cost | 4 | 4 | 6
Interest cost | 23 | 30 | 28
Plan participants' contributions | 15 | 16 |
Actuarial loss | 19 | 28 |
Benefits paid | (75) | (83) |
Obligation at measurement date | 709 | 723 | 728
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 220 | 195 |
Employer contributions | 53 |  |
Actual return on plan assets | 24 | 32 |
Benefits paid | (75) | (83) |
Plan participants' contributions | 15 | 16 |
Employer contributions |  | 60 |
Plan assets at measurement date | 237 | 220 | 195
Funded status of plan | (472) | (503) |
Other Post-Retirement Benefit Plans | Duke Energy Carolinas |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 175 | 174 |
Service cost | 1 | 1 | 1
Interest cost | 5 | 7 | 7
Plan participants' contributions | 3 | 3 |
Actuarial loss | 8 | 9 |
Benefits paid | (18) | (19) |
Obligation at measurement date | 174 | 175 | 174
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 130 | 115 |
Employer contributions | 10 |  |
Actual return on plan assets | 14 | 20 |
Benefits paid | (18) | (19) |
Plan participants' contributions | 3 | 3 |
Employer contributions |  | 11 |
Plan assets at measurement date | 139 | 130 | 115
Funded status of plan | (35) | (45) |
Other Post-Retirement Benefit Plans | Progress Energy |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 303 | 303 |
Service cost | 1 | 1 | 1
Interest cost | 10 | 12 | 12
Plan participants' contributions | 5 | 6 |
Actuarial loss | 8 | 13 |
Benefits paid | (28) | (32) |
Obligation at measurement date | 299 | 303 | 303
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | (1) | 0 |
Employer contributions | 23 |  |
Actual return on plan assets | 0 | (1) |
Benefits paid | (28) | (32) |
Plan participants' contributions | 5 | 6 |
Employer contributions |  | 26 |
Plan assets at measurement date | (1) | (1) | 0
Funded status of plan | (300) | (304) |
Other Post-Retirement Benefit Plans | Duke Energy Progress |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 168 | 166 |
Service cost | 0 | 0 | 0
Interest cost | 5 | 7 | 6
Plan participants' contributions | 3 | 3 |
Actuarial loss | 5 | 9 |
Benefits paid | (15) | (17) |
Obligation at measurement date | 166 | 168 | 166
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | (1) | 0 |
Employer contributions | 11 |  |
Actual return on plan assets | 0 | 0 |
Benefits paid | (15) | (17) |
Plan participants' contributions | 3 | 3 |
Employer contributions |  | 13 |
Plan assets at measurement date | (2) | (1) | 0
Funded status of plan | (168) | (169) |
Other Post-Retirement Benefit Plans | Duke Energy Florida |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 135 | 137 |
Service cost | 0 | 1 | 1
Interest cost | 4 | 5 | 6
Plan participants' contributions | 2 | 2 |
Actuarial loss | 2 | 5 |
Benefits paid | (13) | (15) |
Obligation at measurement date | 130 | 135 | 137
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 0 | 0 |
Employer contributions | 10 |  |
Actual return on plan assets | 0 | 0 |
Benefits paid | (13) | (15) |
Plan participants' contributions | 2 | 2 |
Employer contributions |  | 13 |
Plan assets at measurement date | (1) | 0 | 0
Funded status of plan | (131) | (135) |
Other Post-Retirement Benefit Plans | Duke Energy Ohio |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 29 | 29 |
Service cost | 0 | 0 | 1
Interest cost | 1 | 1 | 1
Plan participants' contributions | 1 | 1 |
Actuarial loss | 0 | 1 |
Benefits paid | (4) | (3) |
Obligation at measurement date | 27 | 29 | 29
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 9 | 8 |
Employer contributions | 3 |  |
Actual return on plan assets | 0 | 1 |
Benefits paid | (4) | (3) |
Plan participants' contributions | 1 | 1 |
Employer contributions |  | 2 |
Plan assets at measurement date | 9 | 9 | 8
Funded status of plan | (18) | (20) |
Other Post-Retirement Benefit Plans | Duke Energy Indiana |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 64 | 67 |
Service cost | 1 | 1 | 1
Interest cost | 2 | 3 | 3
Plan participants' contributions | 2 | 2 |
Actuarial loss | 1 | 2 |
Benefits paid | (9) | (11) |
Obligation at measurement date | 61 | 64 | 67
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 5 | 5 |
Employer contributions | 8 |  |
Actual return on plan assets | 1 | 0 |
Benefits paid | (9) | (11) |
Plan participants' contributions | 2 | 2 |
Employer contributions |  | 9 |
Plan assets at measurement date | 7 | 5 | 5
Funded status of plan | (54) | (59) |
Other Post-Retirement Benefit Plans | Piedmont |  |  |
Change in Projected Benefit Obligation [Rollforward] |  |  |
Obligation at prior measurement date | 30 | 30 |
Service cost | 0 | 0 | 1
Interest cost | 1 | 1 | 1
Plan participants' contributions | 0 | 0 |
Actuarial loss | 1 | 0 |
Benefits paid | (2) | (1) |
Obligation at measurement date | 30 | 30 | 30
Change in Fair Value of Plan Assets [Rollforward] |  |  |
Plan assets at prior measurement date | 34 | 29 |
Employer contributions | 1 |  |
Actual return on plan assets | 4 | 6 |
Benefits paid | (2) | (1) |
Plan participants' contributions | 0 | 0 |
Employer contributions |  | 0 |
Plan assets at measurement date | 37 | 34 | $ 29
Funded status of plan | $ 7 | $ 4 |

X
- Definition Value of benefit obligation transferred into (out of) a defined benefit pension plan. + References No definition available. + Details
Name: | duk_DefinedBenefitObligationTransferredToFromPlan
Namespace Prefix: | duk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of contribution and contributions, net, received by defined benefit plan from employer which increases (decreases) plan assets. + References No definition available. + Details
Name: | duk_DefinedBenefitPlanContributionsReimbursementNetByEmployer
Namespace Prefix: | duk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + 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 (e) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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
Name: | us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. + 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 (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanActuarialGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in plan assets of defined benefit plan from assets transferred into (from) plan. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + 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 (a) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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://www.xbrl.org/2003/role/disclosureRef -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://www.xbrl.org/2003/role/disclosureRef -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
Name: | us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of contributions received by defined benefit plan from participant which increase benefit obligation. + 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 (a)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of payment, which decreases benefit obligation of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. Excludes decreases to benefit obligation for remeasurement due to settlement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(10) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. + References Reference 1: 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 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + 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 (d)(iv)(01) -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 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: 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 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: 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
Name: | us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cost recognized for passage of time related to defined benefit plan. + 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 (h)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 3: 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 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanInterestCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of payment to participant under defined benefit plan which decreases plan assets. 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://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(5) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -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
Name: | us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of contributions received by defined benefit plan from participant which increases plan assets. + 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)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + 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 (h)(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 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 + Details
Name: | us-gaap_DefinedBenefitPlanServiceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. + 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)(8) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanSettlementsPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_DukeEnergyCarolinasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_ProgressEnergyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_DukeEnergyProgressMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_DukeEnergyFloridaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_DukeEnergyOhioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_DukeEnergyIndianaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=duk_PiedmontNaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_QualifiedPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |