Debt And Credit Facilities (Summary Of Debt And Related Terms) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Debt Instrument [Line Items]
Secured debt	$ 64		$ 66
First mortgage bonds	650		583
Non-recourse notes payable of variable interest entities	273		216
Notes payable and commercial paper			450	[1]
Total debt	21,000	[2]	18,426	[2]
Short-term notes payable and commercial paper	(154)
Current maturities of long-term debt	(1,894)		(275)
Total long-term debt	18,679		17,935
Tax Exempt Bonds	491	[3],[4],[5],[6]	632	[3],[7],[8],[9]
Letter of credit	231		348
Denominated debt	420		489
Unsecured Debt [Member]
Debt Instrument [Line Items]
Unsecured debt	8,961		8,036
Weighted-Average Rate	5.70%
Year Due, Start	2012
Year Due, End	2037
Secured Debt [Member]
Debt Instrument [Line Items]
Secured debt	1,118		1,167
Weighted-Average Rate	3.70%
Year Due, Start	2012
Year Due, End	2035
First Mortgage Bonds [Member]
Debt Instrument [Line Items]
First mortgage bonds	8,182	[10]	6,689	[10]
Weighted-Average Rate	5.10%	[10]
Year Due, Start	2013
Year Due, End	2041
Capital Leases [Member]
Debt Instrument [Line Items]
Capital leases	306		283
Weighted-Average Rate	7.90%
Year Due, Start	2012
Year Due, End	2047
Other Debt [Member]
Debt Instrument [Line Items]
Other debt	1,597	[11]	1,623	[11]
Weighted-Average Rate	1.90%	[11]
Year Due, Start	2012
Year Due, End	2041
Non-Recourse Notes Payable Of VIEs [Member]
Debt Instrument [Line Items]
Non-recourse notes payable of variable interest entities	273		216
Notes Payable And Commercial Paper [Member]
Debt Instrument [Line Items]
Notes payable and commercial paper	604	[12]	450	[12]
Weighted-Average Rate	0.60%	[12]
Fair Value Hedges Carrying Value Adjustment [Member]
Debt Instrument [Line Items]
Fair value hedge carrying value adjustment	19		25
Unamortized Debt Discount And Premium, Net [Member]
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	(60)		(63)
Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Tax Exempt Bonds	$ 1,515		$ 1,540

[1] Duke Energy has issued $450 million in Commercial Paper, which is backstopped by the master credit facility, and the proceeds are in the form of loans through the money pool to Duke Energy Carolinas of $300 million and Duke Energy Indiana of $150 million as of December 31, 2011.

[2] As of December 31, 2011 and 2010, $420 million and $489 million, respectively, of debt was denominated in Brazilian Reals.

[3] For Duke Energy Carolinas, the master credit facility served as a backstop for the $95 million of tax-exempt bonds outstanding at December 31, 2011.

[4] Of the $491 million of tax-exempt bonds outstanding at December 31, 2011 at Duke Energy, the master credit facility served as a backstop for $287 million of these tax-exempt bonds (of which $27 million is in the form of letters of credit), with the remaining balance backstopped by other specific long-term credit facilities separate from the master credit facility.

[5] All of the $111 million of tax-exempt bonds outstanding at December 31, 2011 at Duke Energy Ohio were backstopped by Duke Energy's master credit facility (of which $27 million is in the form of letters of credit).

[6] Of the $285 million of tax-exempt bonds outstanding at December 31, 2011 at Duke Energy Indiana, $81 million were backstopped by Duke Energy's master credit facility, with the remaining balance backstopped by other specific long-term credit facilities separate from the master credit facility.

[7] Of the $632 million of tax-exempt bonds outstanding at December 31, 2010, at Duke Energy, the master credit facility served as a backstop for $311 million of these tax-exempt bonds (of which $27 million is in the form of letters of credit), with the remaining balance backstopped by other specific long-term credit facilities separate from the master credit facility.

[8] Of the $161 million of tax-exempt bonds outstanding at December 31, 2010 at Duke Energy Ohio, $111 million were backstopped by Duke Energy's master credit facility (of which $27 million is in the form of letters of credit), with the remaining balance backstopped by other specific long-term credit facilities separate from the master credit facility.

[9] Of the $352 million of tax-exempt bonds outstanding at December 31, 2010 at Duke Energy Indiana, $81 million were backstopped by Duke Energy's master credit facility, with the remaining balance backstopped by other specific long-term credit facilities separate from the master credit facility.

[10] As of December 31, 2011, substantially all of USFE&G's electric and gas plant in service is mortgaged under the mortgage bond indentures of Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana.

[11] Includes $1,515 million and $1,540 million of Duke Energy tax-exempt bonds as of December 31, 2011 and 2010, respectively. As of December 31, 2011 and 2010, $650 million and $583 million, respectively, was secured by first mortgage bonds and $231 million and $348 million, respectively, was secured by a letter of credit.

[12] Includes $450 million as of both December 31, 2011 and 2010 that was classified as Long-term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities which back-stop these commercial paper balances, along with Duke Energy's ability and intent to refinance these balances on a long-term basis. The weighted-average days to maturity was 17 days and 14 days as of December 31, 2011 and 2010, respectively.