Employee Benefit Plans (Target and Actual Asset Allocations) (Details)	Dec. 31, 2019	Dec. 31, 2018
Master Trust
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	0.00%	11.00%
Target allocation	0.00%
Master Trust \| Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	27.00%	18.00%
Target allocation	28.00%
Master Trust \| Global private equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	1.00%	2.00%
Target allocation	1.00%
Master Trust \| Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	57.00%	63.00%
Target allocation	58.00%
Master Trust \| Return seeking debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	5.00%	0.00%
Target allocation	4.00%
Master Trust \| Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	3.00%	2.00%
Target allocation	3.00%
Master Trust \| Real estate and cash
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	7.00%	2.00%
Target allocation	6.00%
Master Trust \| Other global securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	0.00%	2.00%
Target allocation	0.00%
OPEB
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
OPEB \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	35.00%	43.00%
Target allocation	33.00%
OPEB \| Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	9.00%	8.00%
Target allocation	7.00%
OPEB \| Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	37.00%	40.00%
Target allocation	45.00%
OPEB \| Real estate
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
OPEB \| Cash
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	17.00%	7.00%
Target allocation	13.00%

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.

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one 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=118257860&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 (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ 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 (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	invest_InvestmentAxis=duk_MasterTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_PrivateEquityFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanDebtSecurityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=duk_DefinedBenefitPlanDebtSecurityReturnSeekingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_HedgeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=duk_DefinedBenefitPlanRealEstateAndCashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=duk_OtherGlobalSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentAxis=duk_OPEBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanCashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: