Regulatory Matters (Narrative) (Details) (USD $)	3 Months Ended					3 Months Ended								3 Months Ended					3 Months Ended				0 Months Ended	3 Months Ended	12 Months Ended						3 Months Ended		3 Months Ended							3 Months Ended								3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Duke Energy Carolinas [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] North Carolina Rate Case [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] South Carolina Rate Case [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] William State Lee III Nuclear Station [Member] MW	Mar. 31, 2013 Duke Energy Progress [Member]	Dec. 31, 2012 Duke Energy Progress [Member]	Mar. 31, 2013 Duke Energy Progress [Member] Plants Retired [Member]	Mar. 31, 2013 Duke Energy Progress [Member] North Carolina Rate Case [Member]	Mar. 31, 2013 Duke Energy Progress [Member] L V Sutton Plant [Member]	Mar. 31, 2013 Duke Energy Progress [Member] Shearon Harris Nuclear Station [Member]	Mar. 31, 2013 Duke Energy Florida [Member]	Dec. 31, 2012 Duke Energy Florida [Member]	Mar. 31, 2013 Duke Energy Florida [Member] FPSC Settlement Agreement [Member]	Mar. 31, 2012 Duke Energy Florida [Member] FPSC Settlement Agreement [Member]	Mar. 31, 2013 Duke Energy Florida [Member] FPSC Settlement Agreement [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Florida [Member] FPSC Settlement Agreement [Member] Maximum [Member]	Apr. 25, 2013 Duke Energy Florida [Member] Crystal River Unit 3 [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Crystal River Unit 3 [Member]	Dec. 31, 2012 Duke Energy Florida [Member] Crystal River Unit 3 [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Crystal River Unit 3 [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Crystal River Unit 3 [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Levy Nuclear Station [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Levy Nuclear Station [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Levy Nuclear Station [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Mar. 31, 2013 Duke Energy Ohio [Member] Ohio Electric Rate Case [Member]	Mar. 31, 2013 Duke Energy Ohio [Member] Ohio Natural Gas Rate Case [Member]	Mar. 31, 2013 Duke Energy Ohio [Member] RTO Realignment [Member]	Mar. 31, 2013 Duke Energy Indiana [Member]	Mar. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2012 Duke Energy Indiana [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Plants Retired [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member]	Mar. 31, 2012 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] September 7, 2006 [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] May 1, 2008 [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] April 16, 2010 [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] June 27, 2011 [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] October 19, 2011 [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] April 30, 2012 Settlement Agreement [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Edwardsport IGCC Plant [Member] October 30, 2012 [Member]
Plant capacity, MW										1,117
Estimated AFUDC on capital project																																											$ 125,000,000	$ 160,000,000
Estimated capital cost of new utility plant, including AFUDC															600,000,000														19,000,000,000	24,000,000,000
Percentage of completion of construction															77.00%
Net property, plant and equipment	68,813,000,000		68,558,000,000	22,964,000,000	22,826,000,000					330,000,000	13,179,000,000	13,062,000,000				70,000,000	9,513,000,000	9,360,000,000													8,139,000,000	8,126,000,000				8,373,000,000		8,320,000,000
VC summer ownership percentage						5.00%	10.00%
Approved rate increase amount by state commission																			150,000,000														49,000,000
Rate increase begin date																																	5/1/2013
Return on equity percentage								11.25%	11.25%					10.20%							9.50%	11.50%											9.84%	9.84%
Average increase in retail revenues, percentage								9.70%	15.10%																								2.90%
Capital structure, equity percentage								53.00%	53.00%					53.00%
Capital structure, long-term debt percentage								47.00%	47.00%
Rate Increase, Year One														151,000,000
Average increase in retail revenues, percentage, year one														4.70%
Rate Increase, Year Two														31,000,000
Average increase in retail revenues, percentage, year two														1.00%
Edwardsport IGCC original estimated and approved capital cost, including AFUDC																																										1,985,000,000
Edwardsport IGCC revised estimated capital cost, including AFUDC																																											2,350,000,000	2,880,000,000
Edwardsport IGCC - cost cap for customers																																															2,595,000,000
Impairment charges	0	402,000,000																																		0	400,000,000			897,000,000	420,000,000
Edwardsport IGCC revised estimated capital costs, excluding AFUDC																																													2,820,000,000	2,980,000,000		3,150,000,000
Edwardsport damages																																								560,000,000
Joint intervenors recommended rate disallowances																																								77,000,000
EPA compliance capital costs																																				395,000,000
Requested rate increase amount to state commission								446,000,000	220,000,000
Capacity rider revenues requested																															728,000,000
MGP remediation cost revenue requirement																																		22,000,000
MVP project costs approved by MISO																																			5,200,000,000
Repair costs, range of possible costs																										900,000,000	1,300,000,000
NEIL coverage per company at each nuclear plant																								1,060,000,000
Insurance deductible per claim																								10,000,000
Future Year Four Pro Rata Replacement Power Refund																								40,000,000
Future year five pro rata replacement power refund																								60,000,000
Net unrecovered investment																								1,711,000,000	1,637,000,000			343,000,000
Public utilities cost of removal reserve reduction taken subject to regulatory order																			56,000,000	58,000,000
Public utilities, cost of removal reserve, amount subject to regulatory order																			58,000,000
Current year customer refunds																			129,000,000
Future year two customer refunds																			129,000,000
Refund to customers recorded as reduction to revenue																			288,000,000
Future year two residential and small commercial customer refunds																			10,000,000
Future year three residential and small commercial customer refunds																			10,000,000
Future year four residential and small commercial customer refunds																			10,000,000
Independent review repair costs																										1,490,000,000	3,430,000,000
Decommissioning cost study estimate																								989,000,000
Total insurance proceeds received to date for Crystal River Unit 5																							530,000,000	835,000,000	305,000,000
Regulatory Assets, Noncurrent	10,778,000,000		11,004,000,000	1,707,000,000	1,727,000,000						1,791,000,000	1,845,000,000	125,000,000				3,243,000,000	3,321,000,000													582,000,000	579,000,000			71,000,000	785,000,000		810,000,000	60,000,000
Regulatory Liability, Noncurrent	$ 5,555,000,000		$ 5,584,000,000	$ 2,214,000,000	$ 2,102,000,000						$ 1,598,000,000	$ 1,538,000,000					$ 724,000,000	$ 787,000,000													$ 255,000,000	$ 254,000,000				$ 746,000,000		$ 741,000,000