Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt issuances	$ 1,250,000,000
Current maturities of long-term debt	3,951,000,000	$ 3,244,000,000
Parent Company [Member]
Debt Instrument [Line Items]
Debt issuances	250,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances	1,000,000,000
Current maturities of long-term debt	805,000,000	$ 1,205,000,000
Duke Energy Carolinas [Member] \| Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	300,000,000
Unsecured Debt [Member] \| March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250,000,000
Interest rate	3.95%
Unsecured Debt [Member] \| Parent Company [Member] \| March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250,000,000
First Mortgage [Member] \| March 2018 Debt Issuance 3.050% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
Interest rate	3.05%
First Mortgage [Member] \| March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
Interest rate	3.95%
First Mortgage [Member] \| Duke Energy Carolinas [Member] \| March 2018 Debt Issuance 3.050% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
First Mortgage [Member] \| Duke Energy Carolinas [Member] \| March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
First Mortgage [Member] \| Duke Energy Carolinas [Member] \| Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.10%
Current maturities of long-term debt	$ 300,000,000

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyCarolinasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=duk_FirstMortgageBondsMaturingApril20185.100CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=duk_March2018DebtIssuance3.950CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_FirstMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=duk_March2018DebtIssuance3.050CouponMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=duk_March2018DebtIssuance3.950CouponDue2048Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: