Regulatory Matters (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended					3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended			9 Months Ended		3 Months Ended		9 Months Ended			9 Months Ended						9 Months Ended				3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		9 Months Ended		12 Months Ended		9 Months Ended							9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 FPSC Settlement Agreement [Member]	Sep. 30, 2012 FPSC Settlement Agreement [Member]	Sep. 30, 2012 FPSC Settlement Agreement [Member] Minimum [Member]	Sep. 30, 2012 FPSC Settlement Agreement [Member] Maximum [Member]	Sep. 30, 2012 North Carolina Rate Case [Member]	Sep. 30, 2012 North Carolina Rate Case Net Of Energy Efficiency And Demand Side Management [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Sep. 30, 2011 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Sep. 30, 2011 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Sep. 30, 2011 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Sep. 30, 2011 Duke Energy Ohio [Member]	Dec. 31, 2014 Duke Energy Ohio [Member]	Dec. 31, 2013 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Ohio [Member] Ohio Electric Rate Case [Member]	Sep. 30, 2012 Duke Energy Ohio [Member] Ohio Natural Gas Rate Case [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member]	Sep. 30, 2011 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member]	Sep. 30, 2011 Duke Energy Carolinas [Member]	Dec. 31, 2011 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member] Minimum [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member] Maximum [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member] North Carolina Rate Case [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member] South Carolina Rate Case [Member]	Sep. 30, 2012 Progress Energy Carolinas [Member] North Carolina Rate Case [Member]	Nov. 30, 2009 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] September 7, 2006 [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] May 1, 2008 [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] November 24, 2009 [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] April 16, 2010 [Member]	Sep. 30, 2010 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] September 17, 2010 Settlement Agreement [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] September 17, 2010 Settlement Agreement [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] March 10, 2011 [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] June 27, 2011 [Member]	Sep. 30, 2011 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] October 19, 2011 [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] October 19, 2011 [Member]	Jun. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] April 30, 2012 Settlement Agreement [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] April 30, 2012 Settlement Agreement [Member]	Sep. 30, 2012 Edwardsport IGCC Plant [Member] Duke Energy Indiana [Member] October 30, 2012 [Member]	Sep. 30, 2012 Dan River Facility [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 Cliffside Unit 6 [Member] Duke Energy Carolinas [Member] MWh	Sep. 30, 2012 William State Lee III Nuclear Station [Member] Duke Energy Carolinas [Member] MWh	Dec. 31, 2011 Regional Transmission Organization Realignment [Member] Duke Energy Ohio [Member]	Sep. 30, 2012 Regional Transmission Organization Realignment [Member] Duke Energy Ohio [Member]	Sep. 30, 2012 Crystal River Unit 3 [Member]	Sep. 30, 2012 Crystal River Unit 3 [Member] Planned Scenario [Member] months	Sep. 30, 2012 Crystal River Unit 3 [Member] Previous Bid Scenario [Member] months	Sep. 30, 2012 Crystal River Unit 3 [Member] Expanded Scope Of Work [Member] months	Sep. 30, 2012 Crystal River Unit 3 [Member] Worst Case Scenario [Member] months	Sep. 30, 2012 Crystal River Unit 3 [Member] Minimum [Member]	Sep. 30, 2012 Crystal River Unit 3 [Member] Maximum [Member]	Sep. 30, 2012 Crystal River Unit 3 [Member] FPSC Settlement Agreement [Member]	Sep. 30, 2012 Levy Nuclear Station [Member] Minimum [Member]	Sep. 30, 2012 Levy Nuclear Station [Member] Maximum [Member]	Sep. 30, 2012 Levy Nuclear Station [Member] FPSC Settlement Agreement [Member]	Sep. 30, 2012 Anclote Units 1 and 2 [ Member]	Sep. 30, 2012 H F Lee Energy Complex [Member]	Sep. 30, 2012 L V Sutton Plant [Member]
Plant capacity, MW																																																		825	1,117
Estimated capital cost of new utility plant, excluding AFUDC																																																		$ 1,800
Estimated AFUDC on Capital Project																																				120	125		160											600
Revised Afudc Financing Costs																																																		400
Federal Clean Coal Tax Credits														134													125																							125
Estimated capital cost of new utility plant, including AFUDC																																																	715																	750	600
VC Summer Ownership Percentage																														5.00%	10.00%
Approved Rate Increase Amount by State Commission																																309	93
Rate Increase Begin Date										2013													2013	2013								2/1/2012	2/6/2012
Return on equity percentage										11.30%																						10.50%	10.50%
Average increase in retail revenues, percentage											11.00%												5.10%	6.60%								7.20%	5.98%	12.00%
Capital structure, Equity percentage										55.00%																						53.00%	53.00%
Capital structure, Long-term debt percentage										45.00%																						47.00%	47.00%
Edwardsport IGCC original estimated and approved capital cost, including AFUDC																																				1,985
Edwardsport IGCC revised estimated capital cost, including AFUDC																																					2,350				2,760
Edwardsport IGCC estimated additional capital cost																																						150	530
Edwardsport IGCC - Cost Cap for Customers																																									2,975						2,595
Edwardsport IGCC basis point reduction in the equity return for project construction costs																																									150
Edwardsport IGCC committed costs, as claimed by intervenors																																			1,600
Edwardsport IGCC Impairment charges	266	300	668	309								180	222	580	222	0	79	0	88						31	0	31	0												44				222		400		180
Edwardsport IGCC impairment and other charges																																														420
Edwarsport IGCC original customer rate increase																																										19.00%
Edwardsport IGCC revised customer rate increase																																										16.00%
Edwardsport IGCC revised estimated capital costs, excluding AFUDC																																										2,720	2,820		2,980			3,154
Edwardsport IGCC legal fee charges from settlement																																														20
EPA Compliance Capital Costs														450
Requested Rate Increase Amount to State Commission										387	359												87	45
Ohio ESP non-bypassable stability charge																				110	110	110
MVP project costs approved by MISO																																																				5,200
MISO Exit Liability	111		111		32																				10		10		1																							110	95
MISO exit recorded to regulatory assets																																																				74
MISO exit fees recorded to expense																																																				36
Repair Costs, Range of Possible Costs																																																											900	1,300
Replacement power insurance coverage amount, total																																																						490
NEIL coverage per company at each nuclear plant																																																						2,250
Insurance deductible per claim																																																						10
Nuclear Electric Insurance Limited Reimbursements Withheld																																																						70
Future Year Four Pro Rata Replacement Power Refund																																																													40
Future Year Five Pro Rata Replacement Power Refund																																																													60
Repair Overrun Maximum																																																													400
Authorized Return On Equity On Retired Plant																																																													70.00%
Allocated Wholesale Costs																																																						130										60
Property, Plant and Equipment, Additions, Proposed																																																														19	24		79
Public Utilities Cost Of Removal Reserve Reduction Taken Subject To Regulatory Order						60
Public Utilities, Cost of Removal Reserve, amount subject to regulatory order						169	169
Future Year Two Customer Refunds							129
Future Year Three Customer Refunds							129
Refund To Customers Recorded As Reduction To Revenue							288
Future Year Three Residential And Small Commercial Customer Refunds							10
Future Year Four Residential And Small Commercial Customer Refunds							10
Future Year Five Residential And Small Commercial Customer Refunds							10
Public utilities, rate of returns below threshold, subject to regulatory order							9.50%
Public utilities, rate of returns, authorized									11.50%
Public utilities rate of returns below threshold subject to regulatory order escalated								9.70%
Public utilities rate of return authorized									11.70%
Independent review repair costs																																																							1,490	1,550	2,440	3,430
Independent review, estimated time to return to service																																																							35	31	60	96
Replacement power refund																																																						100
Increase in rates total							$ 150