Regulatory Matters (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Net property, plant and equipment	$ 68,877,000,000		$ 68,877,000,000		$ 68,558,000,000
Impairment charges	386,000,000	0	386,000,000	402,000,000
Regulatory assets, noncurrent	10,864,000,000		10,864,000,000		11,004,000,000
Regulatory liability, noncurrent	5,483,000,000		5,483,000,000		5,584,000,000
Duke Energy Carolinas [Member]
Net property, plant and equipment	23,032,000,000		23,032,000,000		22,826,000,000
Regulatory assets, noncurrent	1,836,000,000		1,836,000,000		1,727,000,000
Regulatory liability, noncurrent	2,223,000,000		2,223,000,000		2,102,000,000
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Regulatory assets, noncurrent	73,000,000		73,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | NCUC [Member]
Return on equity percentage			10.20%
Capital structure, equity percentage			53.00%
Required shareholder contribution to low income customers or agencies.			10,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | NCUC [Member] | Removal Costs [Member]
Regulatory liability, noncurrent	30,000,000		30,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | PSCSC [Member]
Return on equity percentage			10.20%
Capital structure, equity percentage			53.00%
Required shareholder contribution to low income customers or agencies.			4,000,000
Duke Energy Carolinas [Member] | Rate Case [Member] | PSCSC [Member] | Removal Costs [Member]
Regulatory liability, noncurrent	45,000,000		45,000,000
Duke Energy Carolinas [Member] | Rate Case Phase One [Member] | NCUC [Member]
Average increase in retail revenues, percentage			4.50%
Requested rate increase amount to state commission			205,000,000
Duke Energy Carolinas [Member] | Rate Case Phase One [Member] | PSCSC [Member]
Average increase in retail revenues, percentage			5.53%
Requested rate increase amount to state commission			80,000,000
Duke Energy Carolinas [Member] | Rate Case Phase Two [Member] | NCUC [Member]
Average increase in retail revenues, percentage			0.60%
Requested rate increase amount to state commission			30,000,000
Duke Energy Carolinas [Member] | Rate Case Phase Two [Member] | PSCSC [Member]
Average increase in retail revenues, percentage			2.63%
Requested rate increase amount to state commission			38,000,000
Duke Energy Carolinas [Member] | V.C. Summer Nuclear Station [Member] | Minimum [Member]
VC summer ownership percentage			5.00%
Duke Energy Carolinas [Member] | V.C. Summer Nuclear Station [Member] | Maximum [Member]
VC summer ownership percentage			10.00%
Duke Energy Carolinas [Member] | William State Lee III Nuclear Station [Member]
Net property, plant and equipment	350,000,000		350,000,000
Duke Energy Progress [Member]
Net property, plant and equipment	13,310,000,000		13,310,000,000		13,062,000,000
Impairment charges	22,000,000	0	22,000,000	0
Regulatory assets, noncurrent	1,905,000,000		1,905,000,000		1,845,000,000
Regulatory liability, noncurrent	1,564,000,000		1,564,000,000		1,538,000,000
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Regulatory assets, noncurrent	190,000,000		190,000,000
Duke Energy Progress [Member] | Rate Case [Member] | NCUC [Member]
Rate increase begin date			6/1/2013
Return on equity percentage			10.20%
Capital structure, equity percentage			53.00%
Required shareholder contribution to low income customers or agencies.			20,000,000
Duke Energy Progress [Member] | Rate Case [Member] | NCUC [Member] | Removal Costs [Member]
Regulatory liability, noncurrent	20,000,000		20,000,000
Duke Energy Progress [Member] | Rate Case Phase One [Member] | NCUC [Member]
Approved rate increase amount by state commission			147,000,000
Average increase in retail revenues, percentage			4.50%
Duke Energy Progress [Member] | Rate Case Phase Two [Member] | NCUC [Member]
Approved rate increase amount by state commission			31,000,000
Average increase in retail revenues, percentage			1.00%
Duke Energy Progress [Member] | L V Sutton Plant [Member]
Estimated capital cost of new utility plant, including AFUDC	570,000,000		570,000,000
Percentage of completion of construction			88.00%
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Impairment charges			22,000,000
Regulatory assets, noncurrent	47,000,000		47,000,000
Duke Energy Florida [Member]
Net property, plant and equipment	9,425,000,000		9,425,000,000		9,360,000,000
Impairment charges	345,000,000	0	345,000,000	0
Regulatory assets, noncurrent	3,167,000,000		3,167,000,000		3,321,000,000
Regulatory liability, noncurrent	669,000,000		669,000,000		787,000,000
Duke Energy Florida [Member] | 2012 FPSC Settlement Agreement [Member]
Approved rate increase amount by state commission			150,000,000
Public utilities cost of removal reserve reduction taken subject to regulatory order	17,000,000		73,000,000	58,000,000
Public utilities, cost of removal reserve, amount subject to regulatory order	41,000,000		41,000,000
Refund to customers recorded as reduction to revenue			288,000,000
Duke Energy Florida [Member] | 2012 FPSC Settlement Agreement [Member] | Minimum [Member]
Return on equity percentage			9.50%
Duke Energy Florida [Member] | 2012 FPSC Settlement Agreement [Member] | Maximum [Member]
Return on equity percentage			11.50%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member]
Decommissioning trust funding			8,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
NEIL coverage per company at each nuclear plant, prior to retirement	2,250,000,000		2,250,000,000
NEIL coverage per company at each nuclear plant, current	1,060,000,000		1,060,000,000
Insurance deductible per claim	10,000,000		10,000,000
Decommissioning cost study estimate			989,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | Minimum [Member]
Repair costs, range of possible costs	900,000,000		900,000,000
Independent review repair costs	1,490,000,000		1,490,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | Maximum [Member]
Repair costs, range of possible costs	1,300,000,000		1,300,000,000
Independent review repair costs	3,430,000,000		3,430,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2012 FPSC Settlement Agreement [Member]
Refund to customers recorded as reduction to revenue			100,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member]
Impairment charges			295,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | FPSC [Member]
Return on equity percentage			7.35%
Cost Cap for customers	1,466,000,000		1,466,000,000
Acceleration of cash recovery through fuel clause			135,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | NEIL Settlement [Member]
Total insurance proceeds received to date for Crystal River Unit 3			835,000,000
Current year insurance proceeds received to date for Crystal River Unit 3			530,000,000
Regulatory liability, noncurrent	490,000,000		490,000,000
Duke Energy Florida [Member] | Levy Nuclear Station [Member] | 2013 FPSC Settlement Agreement [Member]
Net property, plant and equipment	138,000,000		138,000,000
Impairment charges			65,000,000
Net unrecovered investment	281,000,000		281,000,000
Future customer credit			10,000,000
Regulatory assets, noncurrent	143,000,000		143,000,000
Duke Energy Florida [Member] | New Generation Needs [Member] | 2013 FPSC Settlement Agreement [Member]
Combined cycle capacity, MW			1,150
Additional generation capacity, MW			1,800
Return on equity percentage			10.50%
Duke Energy Ohio [Member]
Net property, plant and equipment	8,170,000,000		8,170,000,000		8,126,000,000
Regulatory assets, noncurrent	564,000,000		564,000,000		579,000,000
Regulatory liability, noncurrent	256,000,000		256,000,000		254,000,000
Duke Energy Ohio [Member] | Electric Rate Case [Member] | PUCO [Member]
Approved rate increase amount by state commission			49,000,000
Rate increase begin date			5/1/2013
Return on equity percentage			9.84%
Average increase in retail revenues, percentage			2.90%
Duke Energy Ohio [Member] | Natural Gas Rate Case [Member] | PUCO [Member]
Return on equity percentage			9.84%
MGP remediation cost revenue requirement			63,000,000
Duke Energy Ohio [Member] | Capacity Rider Filing [Member]
Capacity rider revenues requested			729,000,000
Duke Energy Ohio [Member] | RTO Realignment [Member]
MVP project costs approved by MISO			5,500,000,000
Future revenue requirement discount rate			8.20%
MVP projects future revenue requirements obligation	514,000,000		514,000,000
Recovery costs not sought			121,000,000
Regulatory assets, noncurrent	70,000,000		70,000,000
Duke Energy Indiana [Member]
Net property, plant and equipment	8,445,000,000		8,445,000,000		8,320,000,000
Impairment charges	0	0	0	400,000,000
EPA compliance capital costs			395,000,000
Regulatory assets, noncurrent	769,000,000		769,000,000		810,000,000
Regulatory liability, noncurrent	755,000,000		755,000,000		741,000,000
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Regulatory assets, noncurrent	59,000,000		59,000,000
Duke Energy Indiana [Member] | Edwardsport Event September 7, 2006 [Member]
Edwardsport IGCC original estimated and approved capital cost, including AFUDC			1,985,000,000
Duke Energy Indiana [Member] | Edwardsport Event May 1, 2008 [Member]
Estimated AFUDC on capital project			125,000,000
Edwardsport IGCC revised estimated capital cost, including AFUDC			2,350,000,000
Duke Energy Indiana [Member] | Edwardsport Event April 16, 2010 [Member]
Estimated AFUDC on capital project			160,000,000
Edwardsport IGCC revised estimated capital cost, including AFUDC			2,880,000,000
Duke Energy Indiana [Member] | Edwardsport Event June 27, 2011 [Member]
Edwardsport IGCC revised estimated capital costs, excluding AFUDC			2,820,000,000
Duke Energy Indiana [Member] | Edwardsport Event October 19, 2011 [Member]
Edwardsport IGCC revised estimated capital costs, excluding AFUDC			2,980,000,000
Duke Energy Indiana [Member] | Edwardsport Event October 30, 2012 [Member]
Edwardsport IGCC revised estimated capital costs, excluding AFUDC			3,150,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member]
Public utilities, property, plant and equipment, amount of indirect disallowance of costs of recently completed plants			897,000,000	420,000,000
Edwardsport damages	560,000,000		560,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member] | Edwardsport Event April 30, 2012 Settlement Agreement [Member]
Cost Cap for customers	$ 2,595,000,000		$ 2,595,000,000