Risk Management, Derivative Instruments and Hedging Activities (Notional Amounts of Derivative Instruments) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013 dth GWh		Dec. 31, 2012 GWh dth
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Cash flow hedges	$ 1,140	[1]	$ 1,047	[1]
Undesignated contracts	585		290
Fair value hedges	0		250
Total notional amount	1,725		1,587
Non-recourse long-term debt of variable interest entities	1,259		852
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	67,124		52,104
Natural gas (millions of decatherms)	543,000,000		528,000,000
Cash Flow Hedging [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Non-recourse long-term debt of variable interest entities	592		620
Duke Energy Carolinas [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Non-recourse long-term debt of variable interest entities	300		300
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	1,634		2,028
Progress Energy [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Undesignated contracts			50
Total notional amount			50
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	1,546		1,850
Natural gas (millions of decatherms)	346,000,000		348,000,000
Duke Energy Progress [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Undesignated contracts			50
Total notional amount			50
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	1,546		1,850
Natural gas (millions of decatherms)	129,000,000		118,000,000
Duke Energy Florida [Member]
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Natural gas (millions of decatherms)	217,000,000		230,000,000
Duke Energy Ohio [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Undesignated contracts	27		27
Fair value hedges	0		250
Total notional amount	27		277
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	64,599	[2]	51,215	[2]
Natural gas (millions of decatherms)	197,000,000		180,000,000
Duke Energy Indiana [Member]
Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]
Undesignated contracts	200	[3]	200
Total notional amount	$ 200		$ 200
Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]
Electricity-energy (Gigawatt-hours)	815		97

[1] Duke Energy includes amounts related to non-recourse variable rate long-term debt of VIEs of $592 million and $620 million at June 30, 2013, and at December 31, 2012, respectively.

[2] Amounts at Duke Energy Ohio included intercompany positions that were eliminated at Duke Energy.

[3] In July 2013, $200 million of undesignated interest rate swaps at Duke Energy Indiana were terminated due to a new debt issuance. See Note 6 for more information.