Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($) GWh Mcf	Dec. 31, 2020 USD ($) GWh Mcf
Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 3,025	$ 1,809
Commodity contracts | Cash flow hedges
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	10,427	22,048
Commodity contracts | Electricity (GWh)(a)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	34,427	35,409
Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	744	678
Designated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,344	$ 632
Designated contracts | Interest Rate Contracts | VIE primary beneficiary
Derivative [Line Items]
Notional amount	594	632
Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	1,681	1,177
Undesignated contracts | Interest Rate Contracts | VIE primary beneficiary
Derivative [Line Items]
Notional amount	54
Duke Energy Carolinas | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 350	$ 400
Duke Energy Carolinas | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	206	145
Duke Energy Carolinas | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 350	$ 400
Progress Energy | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,250	$ 750
Progress Energy | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	180	158
Progress Energy | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,250	$ 750
Duke Energy Progress | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 750
Duke Energy Progress | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	180	158
Duke Energy Progress | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 750	$ 750
Duke Energy Florida | Interest Rate Contracts
Derivative [Line Items]
Notional amount	500
Duke Energy Florida | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	500
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	3,727	2,559
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	20,273	10,802
Duke Energy Indiana | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	4	2
Piedmont | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	354	373