Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Bcf in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($) GWh Bcf	Dec. 31, 2014 USD ($) GWh Bcf
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	75	25,370
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf	360	676
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 1,241	$ 1,027
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf	63	35
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf	297	328
Progress Energy [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 500	$ 250
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf	109	116
Duke Energy Progress [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf	188	212
Duke Energy Florida [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 250
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh		19,141
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Bcf		313
Duke Energy Ohio [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	18
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 714	750
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	527	277
Not Designated as Hedging Instrument [Member] | Progress Energy [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	500	250
Not Designated as Hedging Instrument [Member] | Duke Energy Progress [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250
Floating interest rate	1.75%
Not Designated as Hedging Instrument [Member] | Duke Energy Florida [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250	250
Not Designated as Hedging Instrument [Member] | Duke Energy Ohio [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	27	27
Variable Interest Entity, Primary Beneficiary [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 509	$ 541