Summary of Significant Accounting Policies (Other Assets and Liabilities)(Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	$ 757	$ 765
Duke Energy Carolinas [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	121	155
Accrued compensation	252	248
Progress Energy [Member] \| Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	278	19
Progress Energy [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	338	363
Duke Energy Progress [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	129	141
Accrued compensation	132	135
Duke Energy Florida [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	208	222
Duke Energy Ohio [Member] \| Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	36	16
Duke Energy Ohio [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	46	62
Duke Energy Indiana [Member] \| Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	45	44
Piedmont Natural Gas [Member] \| Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	$ 43	$ 9

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The current portion of money or property received from customers which is either to be returned upon satisfactory contract completion or applied to customer receivables in accordance with the terms of the contract or the understandings.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Carrying amount due within one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Name Accounting Standards Codification
-Topic 210
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