2.2.0.7 false Risk Management, Derivative Instruments and Hedging Activities (Table 1) (Details) 40702 - Disclosure - Risk Management, Derivative Instruments and Hedging Activities (Table 1) (Details) true false false false 1 USD false false Unit13 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Unit12 Standard http://www.xbrl.org/2003/instance pure xbrli 0 Unit1 Standard http://www.xbrl.org/2003/instance shares xbrli 0 Unit14 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 false false Unit12 Standard http://www.xbrl.org/2003/instance pure xbrli 0 5 Electricity-energy (Gigawatt-hours) 3 duk_ElectricityEnergyGigawattHours duk false na duration Electricity Energy Gigawatt Hours false false false false false false false false false false false terselabel false 1 false true false false 6208 6208 false false false 2 false true false false 3687 3687 false false false xbrli:integerItemType integer Electricity Energy Gigawatt Hours No authoritative reference available. false 6 Electricity-Capacity (Gigawatt-months) 3 duk_ElectricityCapacityGigawattHours duk false na duration Electricity-Capacity (Gigawatt-hours) false false false false false false false false false false false terselabel false 1 false true false false 103 103 false false false 2 false false false false 0 0 false false false xbrli:integerItemType integer Electricity-Capacity (Gigawatt-hours) No authoritative reference available. false 7 Emission allowances: SO2 (thousands of tons) 3 duk_EmissionAllowancesSo2ThousandsOfTons duk false na duration Emission Allowances SO2 Thousands Of Tons false false false false false false false false false false false terselabel false 1 false true false false 8 8 false false false 2 false true false false 9 9 false false false xbrli:integerItemType integer Emission Allowances SO2 Thousands Of Tons No authoritative reference available. false 8 Emission Allowances NOx (thousands Of tons) 3 duk_EmissionAllowancesNo2ThousandsOfTons duk false na duration Emission Allowances NO2 Thousands Of Tons false false false false false false false false false false false terselabel false 1 false true false false 1 1 false false false 2 false true false false 2 2 false false false xbrli:integerItemType integer Emission Allowances NO2 Thousands Of Tons No authoritative reference available. false 9 Natural gas (millions of decatherms) 3 duk_NaturalGasMillionsOfDecatherms duk false na duration Natural Gas Millions Of Decatherms false false false false false false false false false false false terselabel false 1 false true false false 71 71 false false false 2 false true false false 71 71 false false false xbrli:integerItemType integer Natural Gas Millions Of Decatherms No authoritative reference available. false 10 Coal (millions of tons) 3 duk_CoalMillionsOfTons duk false na duration Coal Millions Of Tons false false false false false false false false false false false terselabel false 1 false true false false 1 1 false false false 2 false true false false 2 2 false false false xbrli:integerItemType integer Coal Millions Of Tons No authoritative reference available. false 2 6 false UnKnown UnKnown UnKnown false true