Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) GWh Mcf	Dec. 31, 2019 USD ($) GWh Mcf
Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 3,018	$ 2,270
Commodity contracts | Electricity (GWh)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	6,737	15,858
Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	709	704
Designated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 991	$ 993
Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	2,027	1,277
VIE primary beneficiary | Designated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	691	693
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 decatherms) | Mcf	145	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	$ 1,600	$ 800
Progress Energy | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	158	160
Progress Energy | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,600	$ 800
Duke Energy Progress | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,050	$ 250
Duke Energy Progress | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	158	160
Duke Energy Progress | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 1,050	$ 250
Duke Energy Florida | Interest Rate Contracts
Derivative [Line Items]
Notional amount	550	550
Duke Energy Florida | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	550	550
Duke Energy Ohio | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Ohio | Commodity contracts | Electricity (GWh)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	977	1,887
Duke Energy Ohio | Undesignated contracts | Interest Rate Contracts
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Indiana | Commodity contracts | Electricity (GWh)
Derivative [Line Items]
Notional amount, energy measure (in gigawatt-hours) | GWh	5,760	13,971
Duke Energy Indiana | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	4	3
Piedmont Natural Gas | Commodity contracts | Natural gas (millions of dekatherms)
Derivative [Line Items]
Notional amount, volume (in millions of decatherms) | Mcf	402	411