Commitments And Contingencies (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013		Dec. 31, 2012		Dec. 31, 2009
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	$ 84,000,000
Probable insurance recoveries	781,000,000	[1],[2]	781,000,000	[1],[2]
Reserves for legal matters	834,000,000	[3],[4]	846,000,000	[3],[4]
Minimum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated cost of complying with recently issued and proposed EPA regulations	5,000,000,000
Maximum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated cost of complying with recently issued and proposed EPA regulations	6,000,000,000
Alaskan Global Warming Lawsuit [Member] | Minimum [Member]
Valuation and Qualifying Accounts [Abstract]
Amount of claim(s)	95,000,000
Alaskan Global Warming Lawsuit [Member] | Maximum [Member]
Valuation and Qualifying Accounts [Abstract]
Amount of claim(s)	400,000,000
Brazil Expansion Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Obligation to expand installed generation capacity, percent	15.00%
Crescent Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Amount of claim(s)	1,200,000,000
Duke Energy Carolinas [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	29,000,000
New Source Review maximum civil penalties per day for each violation	37,500
Probable insurance recoveries	781,000,000	[1],[2]	781,000,000	[1],[2]
Reserves for legal matters	743,000,000	[3],[4]	751,000,000	[3],[4]
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
Valuation and Qualifying Accounts [Abstract]
Number of nonmalignant asbestos related claims	99
Cumulative relief sought for nonmalignant asbestos related claims	18,000,000
Number of malignant asbestos related claims	46
Cumulative relief sought for malignant asbestos related claims	15,000,000
Asbestos-related injuries and damages reserves	743,000,000		751,000,000
Asbestos related injuries and damages self insured retention	476,000,000
Policy limit for potential future insurance recoveries for indemnification and medical cost claim payments in excess of self insured limit	935,000,000
Progress Energy [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	7,000,000
Reserves for legal matters	75,000,000	[3]	79,000,000	[3]
Progress Energy [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency asserted damage	113,000,000
Progress Energy [Member] | Synthetic Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Judgment payment					154,000,000
Damages awarded to plaintiff	90,000,000
Gain recognized in period			63,000,000
Duke Energy Progress [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	3,000,000
Reserves for legal matters	11,000,000	[3]	12,000,000	[3]
Duke Energy Progress [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency asserted damage	90,000,000
Duke Energy Florida [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	4,000,000
Reserves for legal matters	44,000,000	[3],[5]	47,000,000	[3],[5]
Duke Energy Florida [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency asserted damage	23,000,000
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	43,000,000
Duke Energy Indiana [Member]
Valuation and Qualifying Accounts [Abstract]
Loss exposure in excess of accrual, high estimate	5,000,000
Reserves for legal matters	$ 7,000,000	[3]	$ 8,000,000	[3]

[1] Insurance recoveries are classified in the respective Condensed Consolidated Balance Sheets in Other within Investments and Other Assets and Receivables.

[2] Relates to recoveries associated with aforementioned asbestos-related injuries and damages claims.

[3] Reserves are classified in the respective Condensed Consolidated Balance Sheets in Other within Deferred Credits and Other Liabilities and Other within Current Liabilities.

[4] Includes reserves for aforementioned asbestos-related injuries and damages claims.

[5] Includes workers' compensation claims.