XML 161 R104.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments in Unconsolidated Affiliates (Narrative) (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 | Oct. 03, 2016
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Distributions from equity investments |  | $ 108 | $ 13 | $ 31 |  |
Distributions from equity investments, return of capital |  | 137 | 281 | 1 |  |
Income (Loss) from Equity Method Investments |  | 83 | 119 | (15) |  |
Asset Impairment Charges |  | 402 | 282 | 18 |  |
Atlantic Coast Pipeline [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Distributions from equity investments, return of capital |  | 265 |  |  |  |
Electric Utilities and Infrastructure [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Income (Loss) from Equity Method Investments |  | $ 6 | 5 | 5 |  |
Electric Utilities and Infrastructure [Member] | Duke American Transmission Co. [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 50.00% |  |  |  |
Electric Utilities and Infrastructure [Member] | Pioneer Transmission [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 50.00% |  |  |  |
Gas Utilities and Infrastructure [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Income (Loss) from Equity Method Investments |  | $ 27 | 62 | 19 |  |
Gas Utilities and Infrastructure [Member] | Atlantic Coast Pipeline [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 47.00% |  |  |  |
Gas Utilities and Infrastructure [Member] | Constitution Pipeline [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 24.00% |  |  |  |
Commercial Renewables [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Income (Loss) from Equity Method Investments |  | $ (1) | (5) | (82) |  |
Asset Impairment Charges |  |  |  | 71 |  |
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Asset Impairment Charges |  |  |  | 71 |  |
Commercial Renewables [Member] | DS Cornerstone [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 50.00% |  |  |  |
Other [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Income (Loss) from Equity Method Investments |  | $ 51 | $ 57 | $ 43 |  |
Other [Member] | National Methanol Company [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity method investment, ownership percentage |  | 17.50% | 25.00% |  |  |
Board representation and voting rights, ownership percentage |  | 25.00% |  |  |  |
Piedmont Natural Gas [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Distributions from equity investments | $ 1 | $ 1 | $ 4 |  | $ 26 |
Distributions from equity investments, return of capital | 1 | 3 | 2 |  | 18 |
Income (Loss) from Equity Method Investments | $ 2 | $ 7 | (6) |  | 29 |
Asset Impairment Charges |  |  | $ 7 |  |  |
Piedmont Natural Gas [Member] | SouthStar [Member] |  |  |  |  |  |
Investments In Unconsolidated Affiliates [Line Items] |  |  |  |  |  |
Equity Method Investment Ownership Percentage Sold |  |  |  |  |  | 15.00%
Proceeds from Sale of Equity Method Investments |  |  |  |  | 160 |
Gain on Sale of Investments |  |  |  |  | 81 |
Income (Loss) from Equity Method Investments |  |  |  |  | $ 19 |

X
- Definition Equity Method Investment Ownership Percentage Sold + References No definition available. + Details
Name: | duk_EquityMethodInvestmentOwnershipPercentageSold
Namespace Prefix: | duk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition EquityMethodInvestmentVotingRightsOwnershipPercentage + References No definition available. + Details
Name: | duk_EquityMethodInvestmentVotingRightsOwnershipPercentage
Namespace Prefix: | duk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: 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 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities. + References Reference 1: 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 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 Reference 3: 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(12)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21D -URI http://asc.fasb.org/extlink&oid=109223946&loc=SL94080555-108585 + Details
Name: | us-gaap_EquityMethodInvestmentDividendsOrDistributions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(3)(a)) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -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 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(9)(a)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(7)(c)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_GainOnSaleOfInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee. + 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(12)) -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 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 Reference 3: 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 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(f)) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of distribution received from equity method investee for return of investment, classified as investing activities. Excludes distribution for return on investment, classified as operating activities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21D -URI http://asc.fasb.org/extlink&oid=109223946&loc=SL94080555-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_AtlanticCoastPipelineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=duk_ElectricUtilitiesandInfrastructureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_DukeAmericanTransmissionCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_PioneerTransmissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=duk_GasUtilitiesandInfrastructureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_ConstitutionPipelineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=duk_CommercialRenewablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_DSCornerstoneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=duk_OtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_NationalMethanolCompanyMember
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: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=duk_SouthStarMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |