Acquisitions and Sales of Other Assets (Narrative) (Details) (USD $) Share data in Thousands, unless otherwise specified	0 Months Ended	3 Months Ended				12 Months Ended				6 Months Ended	0 Months Ended	12 Months Ended			12 Months Ended	3 Months Ended				12 Months Ended			3 Months Ended				12 Months Ended			3 Months Ended				12 Months Ended			0 Months Ended	3 Months Ended				6 Months Ended	12 Months Ended			0 Months Ended	3 Months Ended				12 Months Ended
	Jul. 02, 2012	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2012 Sumitomo Corporation of America [Member]	Jan. 12, 2012 Wabash Valley Power Association [Member]	Dec. 31, 2012 North Carolina Utilities Commission and Public Service Commission of South Carolina [Member]	Dec. 31, 2012 Kentucky Public Service Commission [Member]	Dec. 31, 2012 Ibener [Member]	Dec. 31, 2010 Dukenet [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2012 Duke Energy Carolinas [Member]	Mar. 31, 2012 Duke Energy Carolinas [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Dec. 31, 2011 Duke Energy Carolinas [Member]	Dec. 31, 2010 Duke Energy Carolinas [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member]	Sep. 30, 2012 Progress Energy Carolinas [Member]	Jun. 30, 2012 Progress Energy Carolinas [Member]	Mar. 31, 2012 Progress Energy Carolinas [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member]	Dec. 31, 2011 Progress Energy Carolinas [Member]	Dec. 31, 2010 Progress Energy Carolinas [Member]	Dec. 31, 2012 Progress Energy Florida [Member]	Sep. 30, 2012 Progress Energy Florida [Member]	Jun. 30, 2012 Progress Energy Florida [Member]	Mar. 31, 2012 Progress Energy Florida [Member]	Dec. 31, 2012 Progress Energy Florida [Member]	Dec. 31, 2011 Progress Energy Florida [Member]	Dec. 31, 2010 Progress Energy Florida [Member]	Jan. 12, 2012 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Jun. 30, 2012 Duke Energy Ohio [Member]	Mar. 31, 2012 Duke Energy Ohio [Member]	Jun. 30, 2011 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Dec. 31, 2011 Duke Energy Ohio [Member]	Dec. 31, 2010 Duke Energy Ohio [Member]	Jan. 12, 2012 Duke Energy Indiana [Member]	Dec. 31, 2012 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Jun. 30, 2012 Duke Energy Indiana [Member]	Mar. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2011 Duke Energy Indiana [Member]	Dec. 31, 2010 Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Duke Energy common shares issued for Progress Energy common shares outstanding	257,867
Exchange Ratio Adjusted for Reverse Stock Split	87.083%
Settlement agreement, customer guaranteed savings						$ 687,000,000
Interim FERC Mitigation Rate Reduction						65,000,000
Costs to achieve the merger		(164,000,000)	(457,000,000)	(7,000,000)	(8,000,000)											(46,000,000)	(184,000,000)	(5,000,000)	(4,000,000)				(36,000,000)	(180,000,000)	(12,000,000)	(4,000,000)				(46,000,000)	(37,000,000)	(8,000,000)	(3,000,000)					(12,000,000)	(22,000,000)	(1,000,000)	(1,000,000)						(11,000,000)	(21,000,000)	(1,000,000)	(1,000,000)
Proceeds						187,000,000	[1]	12,000,000	160,000,000											1,000,000	2,000,000	8,000,000																					6,000,000	7,000,000	13,000,000						0	1,000,000	0
Impairment of other long-lived assets						586,000,000		335,000,000	738,000,000											0	12,000,000	0					0	3,000,000	5,000,000					146,000,000	0	0						9,000,000	2,000,000	89,000,000	837,000,000						579,000,000	234,000,000	44,000,000
Transfer of Other Real Estate																																											28,000,000								26,000,000	0	0
Proceeds From Sale of Interest In Jointly Owned Utility Plant											14,000,000																										82,000,000									68,000,000
Sale of Ownership Interest in Vermillion Generating Station																																					75.00%
Equity Method Investment, Ownership Percentage										50.00%					50.00%
Ownership Interest in Vermillion Generation Station											37.50%																																			62.50%
Construction and 12-year amortizing Term Loan Facility		8,000,000				8,000,000		82,000,000		330,000,000																		5,000,000										8,000,000					8,000,000	8,000,000
Proceeds from Issuance of Other Long-term Debt										319,000,000
After Tax Transaction costs						413,000,000		85,000,000
Community support and charitable contributions expense						92,000,000		0	0			105,000,000								56,000,000	0	0					36,000,000	0	0
Annual Community Support Payment Through 2018													165,000
Business Acquisition, Cost of Acquired Entity, Cash Paid														415,000,000
Business Acquisition, Purchase Price Allocation, Property, Plant and Equipment		23,279,000,000				23,279,000,000								383,000,000
Business Acquisition, Purchase Price Allocation, Intangible Assets Other than Goodwill														30,000,000
Business Acquisition, Purchase Price Allocation, Deferred Tax Liabilities, Noncurrent														57,000,000
BridgeLoan														190,000,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount		12,467,000,000				12,467,000,000								59,000,000
Revolving Loan Under Credit Agreement														200,000,000
Current maturities of long-term debt		3,110,000,000				3,110,000,000		1,894,000,000								406,000,000				406,000,000	1,178,000,000		407,000,000				407,000,000	502,000,000		435,000,000				435,000,000	10,000,000			261,000,000					261,000,000	507,000,000			405,000,000				405,000,000	6,000,000
Percentage of Loan Collateralized By Cash Deposits														101.00%
ProceedsFromDivestitureOfInterestInJointVenture															137,000,000
Net pre-tax gains															$ 139,000,000
Ownership interest										50.00%					50.00%

[1] Duke Energy amount relates to proceeds from the disposition of non-core business assets within the Commercial Power segment for which no material gain or loss was recognized.