Merger Agreement (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended				6 Months Ended				6 Months Ended					3 Months Ended		6 Months Ended		9 Months Ended	3 Months Ended		6 Months Ended		9 Months Ended		6 Months Ended
	Jul. 02, 2012	Jun. 30, 2012		Mar. 31, 2012	Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Duke Energy	Jun. 30, 2012 Duke Energy Carolinas	Jun. 30, 2012 Other Duke Subsidiaries	Jun. 30, 2012 Minimum Duke Energy	Jun. 30, 2012 Maximum Duke Energy	Jun. 30, 2012 PEC	Jun. 30, 2011 PEC	Jun. 30, 2012 PEC	Jun. 30, 2011 PEC	Jun. 30, 2012 PEC	Jun. 30, 2012 PEF	Jun. 30, 2011 PEF	Jun. 30, 2012 PEF	Jun. 30, 2011 PEF	Jun. 30, 2012 PEF	Jun. 30, 2012 Employee Rentention Member	Jun. 30, 2012 Special Termination Benefits [Member]	Jun. 30, 2012 Special Termination Benefits [Member] Minimum	Jun. 30, 2012 Special Termination Benefits [Member] Maximum
Merger Agreement [Line Items]
Merger, Description	On July 2, 2012, Progress Energy consummated the merger with Duke Energy, and became, and will continue as, a direct wholly owned subsidiary of Duke Energy. Under the terms of the merger agreement, each share of Progress Energy common stock was converted into 0.87083 shares of Duke Energy common stock as adjusted for the one-for-three reverse stock split of Duke Energy stock, effected in conjunction with, and immediately prior to, the merger.
Merger Share Exchange Ratio, Adjusted	0.87083
Common Stock Shares, Merger	100
Property, Plant and Equipment, Additions, Proposed, Settlement		$ 110				$ 110
Summer off-peak										800	300						500
Summer on-peak										475	150						325
Winter off-peak										225	225
Winter on-peak										25	25
Settlement Agreement, Fuel Savings		650				650
Interim FERC Mitigation Rate Reduction						65
Community support and charitable contributions						100
Accruals for commitments from merger													450	550
Loss Contingencies [Abstract]
Loss Contingency Unrecorded Estimate Of Possible Loss																									14		225	275
Number of accepted VSP requests																										1,100
Estimated exit cost liability		17				17
Exit cost liability recognized		2	[1]	3		5									1		3		7	1		2		3
Estimated exit cost liability expense allocation												4					9					4
Exit cost liability		10	[2]	8		10	[2]		5
Merger and integration costs, net of tax		$ 13			$ 7	$ 18		$ 21							$ 7	$ 4	$ 11	$ 11		$ 6	$ 3	$ 7	$ 10

[1] PEC and PEF recognized exit costs of $1 million each for the three months ended June 30, 2012, and $3 million and $2 million, respectively, for the six months ended June 30, 2012.

[2] Expense related to the recognition of the cumulative exit cost liability at June 30, 2012, was attributed to PEC and PEF totaling $7 million and $3 million, respectively.