XML 200 R143.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions | 2 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Oct. 31, 2016
Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Amortization of Regulatory Asset |  | $ 5 | $ 7 | $ 8 |
Pension Plan [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 182 |  |  |
Service cost |  | 174 | 159 | 147 |
Interest cost |  | 299 | 328 | 335 |
Expected return on plan assets |  | (559) | (545) | (519) |
Amortization of actuarial loss (gain) |  | 132 | 146 | 134 |
Amortization of prior service cost (credit) |  | (32) | (24) | (17) |
Settlement charge |  |  | 12 | 3 |
Other |  |  | 8 | 8 |
Net periodic costs |  | 22 | 84 | 91 |
Pension Plan [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 2 | 2 | 2 |
Interest cost |  | 12 | 13 | 14 |
Amortization of actuarial loss (gain) |  | 8 | 8 | 8 |
Amortization of prior service cost (credit) |  | (2) | (2) | (1) |
Net periodic costs |  | 20 | 21 | 23 |
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 58 |  |  |
Service cost |  | 56 | 48 | 48 |
Interest cost |  | 72 | 79 | 86 |
Expected return on plan assets |  | (147) | (142) | (142) |
Amortization of actuarial loss (gain) |  | 29 | 31 | 33 |
Amortization of prior service cost (credit) |  | (8) | (8) | (8) |
Other |  |  | 2 | 2 |
Net periodic costs |  | 4 | 10 | 19 |
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 | 1 |  |
Interest cost |  |  | 1 | 1 |
Amortization of actuarial loss (gain) |  |  |  | 1 |
Net periodic costs |  | 1 | 2 | 2 |
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 51 |  |  |
Service cost |  | 49 | 45 | 42 |
Interest cost |  | 94 | 100 | 106 |
Expected return on plan assets |  | (178) | (167) | (168) |
Amortization of actuarial loss (gain) |  | 44 | 52 | 51 |
Amortization of prior service cost (credit) |  | (3) | (3) | (3) |
Other |  |  | 2 | 3 |
Net periodic costs |  | 8 | 29 | 31 |
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Interest cost |  | 4 | 5 | 5 |
Amortization of actuarial loss (gain) |  | 2 | 2 | 1 |
Net periodic costs |  | 6 | 7 | 6 |
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 29 |  |  |
Service cost |  | 28 | 26 | 24 |
Interest cost |  | 43 | 47 | 49 |
Expected return on plan assets |  | (85) | (82) | (82) |
Amortization of actuarial loss (gain) |  | 21 | 23 | 23 |
Amortization of prior service cost (credit) |  | (2) | (2) | (2) |
Other |  |  | 1 | 1 |
Net periodic costs |  | 6 | 13 | 13 |
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Interest cost |  | 1 | 1 | 1 |
Amortization of actuarial loss (gain) |  | 1 | 1 | 1 |
Net periodic costs |  | 2 | 2 | 2 |
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 22 |  |  |
Service cost |  | 21 | 19 | 19 |
Interest cost |  | 50 | 53 | 55 |
Expected return on plan assets |  | (91) | (85) | (84) |
Amortization of actuarial loss (gain) |  | 23 | 29 | 29 |
Amortization of prior service cost (credit) |  | (1) | (1) | (1) |
Other |  |  | 1 | 1 |
Net periodic costs |  | 3 | 16 | 19 |
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Interest cost |  | 2 | 2 | 2 |
Amortization of actuarial loss (gain) |  | 1 | 1 | 1 |
Net periodic costs |  | 3 | 3 | 3 |
Pension Plan [Member] | Duke Energy Ohio [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Amortization of Regulatory Asset |  | 2 | 3 | 4 |
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 5 |  |  |
Service cost |  | 5 | 4 | 4 |
Interest cost |  | 17 | 18 | 19 |
Expected return on plan assets |  | (28) | (27) | (27) |
Amortization of actuarial loss (gain) |  | 5 | 5 | 4 |
Amortization of prior service cost (credit) |  |  | (1) |  |
Other |  |  |  | 1 |
Net periodic costs |  | (1) | (1) | 1 |
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 11 |  |  |
Service cost |  | 10 | 9 | 9 |
Interest cost |  | 23 | 26 | 28 |
Expected return on plan assets |  | (42) | (42) | (42) |
Amortization of actuarial loss (gain) |  | 10 | 12 | 11 |
Amortization of prior service cost (credit) |  | (2) | (2) | (1) |
Other |  |  | 1 | 1 |
Net periodic costs |  | 0 | 4 | 6 |
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 7 |  |  |
Service cost | $ 2 | 7 | 10 |  | $ 11
Interest cost | 2 | 11 | 14 |  | 9
Expected return on plan assets | (4) | (22) | (24) |  | (24)
Amortization of actuarial loss (gain) | 2 | 11 | 11 |  | 8
Amortization of prior service cost (credit) | (1) | (10) | (2) |  | (2)
Settlement charge | 3 |  | 12 |  |
Other |  |  | 1 |  |
Net periodic costs | $ 4 | (3) | 22 |  | 2
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  |  | 0 |  |
Interest cost |  |  | 0 |  |
Settlement charge |  |  |  |  | 1
Net periodic costs |  |  |  |  | 1
Other Post-Retirement Benefit Plans [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 6 | 4 | 3 |
Interest cost |  | 28 | 34 | 35 |
Expected return on plan assets |  | (13) | (14) | (12) |
Amortization of actuarial loss (gain) |  | 6 | 10 | 6 |
Amortization of prior service cost (credit) |  | (19) | (115) | (141) |
Curtailment credit |  |  | (30) |  |
Net periodic costs |  | 8 | (111) | (109) |
Amortization of Regulatory Asset |  | 7 | 7 | 8 |
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 | 1 | 1 |
Interest cost |  | 7 | 8 | 8 |
Expected return on plan assets |  | (8) | (8) | (8) |
Amortization of actuarial loss (gain) |  | 3 | (2) | (3) |
Amortization of prior service cost (credit) |  | (5) | (10) | (14) |
Curtailment credit |  |  | (4) |  |
Net periodic costs |  | (2) | (15) | (16) |
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 |  | 1 |
Interest cost |  | 12 | 13 | 15 |
Amortization of actuarial loss (gain) |  | 1 | 21 | 22 |
Amortization of prior service cost (credit) |  | (8) | (84) | (103) |
Curtailment credit |  |  | (16) |  |
Net periodic costs |  | 6 | (66) | (65) |
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Interest cost |  | 6 | 7 | 8 |
Amortization of actuarial loss (gain) |  | 1 | 12 | 13 |
Amortization of prior service cost (credit) |  | (1) | (54) | (68) |
Net periodic costs |  | 6 | (35) | (47) |
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 |  | 1 |
Interest cost |  | 6 | 6 | 7 |
Amortization of actuarial loss (gain) |  |  | 9 | 9 |
Amortization of prior service cost (credit) |  | (7) | (30) | (35) |
Curtailment credit |  |  | (16) |  |
Net periodic costs |  | 0 | (31) | (18) |
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 |  |  |
Interest cost |  | 1 | 1 | 1 |
Amortization of actuarial loss (gain) |  |  | (2) | (2) |
Amortization of prior service cost (credit) |  | (1) |  |  |
Curtailment credit |  |  | (2) |  |
Net periodic costs |  | 1 | (3) | (1) |
Amortization of Regulatory Asset |  | 2 | 2 | 2 |
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 |  |  |
Interest cost |  | 3 | 3 | 4 |
Expected return on plan assets |  |  | (1) | (1) |
Amortization of actuarial loss (gain) |  | 4 | (1) | (1) |
Amortization of prior service cost (credit) |  | (1) | (1) | (1) |
Curtailment credit |  |  | (2) |  |
Net periodic costs |  | 7 | (2) | $ 1 |
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 1 | 1 |  | 1
Interest cost |  | 1 | 1 |  | 1
Expected return on plan assets |  | (2) | (2) |  | (2)
Amortization of actuarial loss (gain) |  |  | 1 |  | 1
Amortization of prior service cost (credit) |  | (2) | 0 |  |
Net periodic costs |  | $ (2) | $ 1 |  | $ 1

X
- Definition Defined Benefit Plan, Service Cost (Non-Capitalized Amount) + References No definition available. + Details
Name: | duk_DefinedBenefitPlanServiceCostNonCapitalizedAmount
Namespace Prefix: | duk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The expense charged against earnings during the period to allocate the capitalized costs of regulatory assets over the periods expected to benefit from such costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.3) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_AmortizationOfRegulatoryAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of 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)(4) -URI http://asc.fasb.org/extlink&oid=108410482&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=112275985&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)(4) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. + 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=112275985&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(5) -URI http://asc.fasb.org/extlink&oid=108410482&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 (a)(5) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. + 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=112275985&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=108410482&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 (a)(3) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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=108410482&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=112275985&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 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 Reference 4: 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=108410482&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 net periodic benefit cost (credit) 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 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 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=112275985&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 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of defined benefit plan cost (credit), classified as other. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanOtherCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from event reducing expected years of future service of present employees or eliminating accrual of defined benefits for some or all future services of present employees. + 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)(7) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. + 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)(7) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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=108410482&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=112275985&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=108410482&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=108410482&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanServiceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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