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Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 USD ($) GWh Mcf | Dec. 31, 2017 USD ($) GWh Mcf | Dec. 31, 2016 USD ($) | Aug. 31, 2016 USD ($)
Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 2,644 | $ 1,587 |  |
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | 923 | 660 |  |
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 1,721 | $ 927 |  |
Commodity Contracts [Member] | Electricity [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, energy measure, in gigawatt-hours | GWh | 15,286 | 34 |  |
Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 739 | 770 |  |
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 422 | $ 660 |  |
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | 194 |  |  |
Piedmont Natural Gas [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Loss on Interest Rate Derivative Instruments Not Designated as Hedging Instruments |  |  | $ 190 |
Piedmont Natural Gas [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount |  |  |  | $ 1,400
Duke Energy Carolinas [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | 300 | 400 |  |
Duke Energy Carolinas [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 300 | $ 400 |  |
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 121 | 105 |  |
Progress Energy [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 1,200 | $ 500 |  |
Progress Energy [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 1,200 | $ 500 |  |
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 169 | 183 |  |
Duke Energy Progress [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 650 | $ 250 |  |
Duke Energy Progress [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 650 | $ 250 |  |
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 166 | 133 |  |
Duke Energy Florida [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 550 | $ 250 |  |
Duke Energy Florida [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 550 | $ 250 |  |
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 3 | 50 |  |
Duke Energy Ohio [Member] | Interest Rate Contract [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 27 | $ 27 |  |
Duke Energy Ohio [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional Amount | $ 27 | $ 27 |  |
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Electricity [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, energy measure, in gigawatt-hours | GWh | 1,786 |  |  |
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Electricity [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, energy measure, in gigawatt-hours | GWh | 13,500 | 34 |  |
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 1 | 2 |  |
Piedmont Natural Gas [Member] | Commodity Contracts [Member] | Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount, volume in millions of decatherms | Mcf | 448 | 480 |  |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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