Debt and Credit Facilities (Narrative) (Details) - USD ($)	9 Months Ended
Sep. 30, 2018	Aug. 31, 2018
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size	$ 8,000,000,000
Line of credit facility, expiration date	Mar. 16, 2023
Three Year Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size	$ 1,000,000,000.0
Outstanding balance	500,000,000
Duke Energy Carolinas [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size	1,750,000,000
Duke Energy Carolinas [Member] \| USDOJ [Member] \| North Carolina Ash Basins [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Minimum master credit facility balance required	250,000,000
Duke Energy Progress [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size	1,400,000,000
Piedmont Natural Gas [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size	500,000,000
Debt Maturing September 2019, 2.848% Coupon [Member] \| Piedmont Natural Gas [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Facility size	350,000,000	$ 250,000,000
Outstanding balance	$ 350,000,000

Minimum Master Credit Facility Balance Required to be maintained to meet obligations outlined in Plea Agreements

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- 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

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Balance Type:	na
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

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