Value of input used to measure net derivative asset (liability).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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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.

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- Definition

Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19279-110258

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Fair Value Measurements (Quantitative Level 3 Fair Value Disclosures) (Details) $ in Millions	Sep. 30, 2018 USD ($) $ / MWh $ / MMBTU	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($) $ / MWh $ / MMBTU	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ (116)	$ (97)	$ (114)	$ (93)	$ (91)	$ (166)
Duke Energy Ohio [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	8	9	1	$ 2	3	5
Duke Energy Ohio [Member] \| Financial Transmission Rights [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ 8		1
Duke Energy Ohio [Member] \| Financial Transmission Rights [Member] \| Minimum [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MWh	1.03			0.07
Duke Energy Ohio [Member] \| Financial Transmission Rights [Member] \| Maximum [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MWh	4.10			1.41
Duke Energy Indiana [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ 29	44	27	$ 28	51	16
Duke Energy Indiana [Member] \| Financial Transmission Rights [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ 29		27
Duke Energy Indiana [Member] \| Financial Transmission Rights [Member] \| Minimum [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MWh	(2.32)			(0.77)
Duke Energy Indiana [Member] \| Financial Transmission Rights [Member] \| Maximum [Member] \| Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MWh	8.11			7.44
Piedmont Natural Gas [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ (153)	$ (150)	(142)	$ (123)	$ (145)	$ (187)
Piedmont Natural Gas [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques
Net derivative asset (liability)	$ (153)		$ (142)
Piedmont Natural Gas [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Minimum [Member] \| Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MMBTU	1.74			2.10
Piedmont Natural Gas [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Maximum [Member] \| Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques
Input measurements (in usd per MWh and usd per MMBtu) \| $ / MMBTU	3.41			2.88