Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Bcf in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) GWh Bcf	Dec. 31, 2014 USD ($) GWh Bcf	Jan. 31, 2016 USD ($)	Oct. 31, 2015 USD ($)	Jan. 31, 2015 USD ($)
Derivative [Line Items]
Undesignated Commodity Contracts Latest Expiration Year	2048
Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 2,527	$ 1,027
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	70	25,370
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	398	676
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 700	$ 750
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	1,827	277
Variable Interest Entity, Primary Beneficiary [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	497	$ 541
Subsequent Event [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount			$ 500
Piedmont Natural Gas [Member]
Derivative [Line Items]
Notional amount	900
Piedmont Natural Gas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	900
Duke Energy Carolinas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 400			$ 400
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	66	35
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 400
Progress Energy [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 500	$ 250
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	332	328
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 500	$ 250
Duke Energy Progress [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	117	116
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Floating interest rate					1.75%
Notional amount	$ 250				$ 250
Duke Energy Florida [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 250
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	215	212
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 250
Duke Energy Ohio [Member] | Interest Rate Contract [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	34	19,141
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf		313
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [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	36