Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) GWh Mcf	Dec. 31, 2019 USD ($) GWh Mcf
Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,830	$ 2,270
Commodity contracts | Cash flow hedges
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	11,116
Commodity contracts | Electricity (GWh)(a)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	32,314	15,858
Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	683	704
Designated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 653	$ 993
Designated contracts | Interest Rate Contracts | VIE primary beneficiary
Derivative [Line Items]
Notional amount	653	693
Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	1,177	1,277
Duke Energy Carolinas | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 400	$ 450
Duke Energy Carolinas | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	143	130
Duke Energy Carolinas | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 400	$ 450
Progress Energy | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 800
Progress Energy | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	156	160
Progress Energy | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 800
Duke Energy Progress | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 250
Duke Energy Progress | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	156	160
Duke Energy Progress | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 250
Duke Energy Florida | Interest Rate Contracts
Derivative [Line Items]
Notional amount		550
Duke Energy Florida | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount		550
Duke Energy Ohio | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Ohio | Commodity contracts | Electricity (GWh)(a)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	4,126	1,887
Duke Energy Ohio | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Indiana | Commodity contracts | Electricity (GWh)(a)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	17,072	13,971
Duke Energy Indiana | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	2	3
Piedmont Natural Gas | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	382	411