Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) GWh Mcf	Dec. 31, 2020 USD ($) GWh Mcf
Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 3,465	$ 1,809
Commodity contracts | Cash flow hedges
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	10,159	22,048
Commodity contracts | Electricity (GWh)(a)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	29,044	35,409
Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	772	678
Designated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 2,094	$ 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	1,371	1,177
Undesignated contracts | Interest Rate Contracts | VIE primary beneficiary
Derivative [Line Items]
Notional amount	94
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	230	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	$ 900	$ 750
Progress Energy | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	190	158
Progress Energy | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 900	$ 750
Duke Energy Progress | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 400	$ 750
Duke Energy Progress | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	190	158
Duke Energy Progress | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 400	$ 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	3,004	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	15,881	10,802
Duke Energy Indiana | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	7	2
Piedmont | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of dekatherms) | Mcf	345	373