Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) GWh Mcf	Dec. 31, 2018 USD ($) GWh Mcf
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	25,658	15,286
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	729	739
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 2,608	$ 2,644
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	1,031	923
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	1,577	1,721
Variable Interest Entity, Primary Beneficiary [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	731	422
Variable Interest Entity, Primary Beneficiary [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 194	$ 194
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	130	121
Duke Energy Carolinas [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 450	$ 300
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 450	$ 300
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	175	169
Progress Energy [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 1,100	$ 1,200
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 1,100	$ 1,200
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	175	166
Duke Energy Progress [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 650
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	250	$ 650
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf		3
Duke Energy Florida [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	850	$ 550
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 850	$ 550
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	2,774	1,786
Duke Energy Ohio [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [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	22,884	13,500
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	4	1
Piedmont Natural Gas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	420	448