Business Segments (Business Segment Data) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Unaffiliated Revenues									$ 19,624		$ 14,529		$ 14,272
Operating revenues	5,695	6,722	3,577	3,630	3,368	3,964	3,534	3,663	19,624		14,529		14,272
Interest Expense									1,242		859		840
Depreciation and amortization									2,289		1,806		1,786
Equity in earnings of unconsolidated affiliates									148		160		116
Income tax expense or benefit									705		752		890
Segment income									1,732		1,705		1,317
Add back Noncontrolling interest component									14		8		3
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									36		1		3
Net Income (Loss)	437	598	448	299	290	470	441	513	1,782		1,714		1,323
Capital investments, expenditures and acquisitions									5,958		4,464		4,855
Segment assets	113,856				62,526				113,856		62,526		59,090
Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,609	1,939	1,616	1,501	1,466	1,868	1,607	1,552	6,665		6,493		6,424
Interest Expense									384		360		362
Depreciation and amortization									921		814		787
Income tax expense or benefit									453		472		457
Net Income (Loss)	130	258	211	266	125	311	193	205	865		834		838
Segment assets	30,642				29,896				30,642		29,896
Progress Energy [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									9,317		8,948		10,223
Intersegment Revenues									88
Operating revenues	2,227	2,788	2,288	2,102	1,752	2,753	2,269	2,174	9,405		8,948		10,223
Interest Expense									740		725		747
Depreciation and amortization									747		701		920
Income tax expense or benefit									172		323		539
Segment income									348		580		860
Add back Noncontrolling interest component									7		7		7
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									52		(5)		(4)
Net Income (Loss)	34	157	64	152	(74)	293	178	185	407		582		863
Capital investments, expenditures and acquisitions									2,366		2,256		2,445
Segment assets	37,405				34,931				37,405		34,931		32,886
Progress Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,128	1,398	1,090	1,090	1,013	1,331	1,069	1,134	4,706		4,547		4,933
Interest Expense									207		184		186
Depreciation and amortization									535		514		478
Income tax expense or benefit									110		256		350
Add back Noncontrolling interest component													(1)
Net Income (Loss)	93	96	31	52	79	199	107	131	272		516		602
Segment assets	18,068				16,066				18,068		16,066
Progress Energy Florida [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,095	1,388	1,196	1,010	737	1,419	1,199	1,037	4,689		4,392		5,276
Interest Expense									255		239		258
Depreciation and amortization									192		169		426
Income tax expense or benefit									147		180		276
Net Income (Loss)	(45)	100	83	128	(104)	203	113	102	266		314		453
Segment assets	15,180				14,294				15,180		14,294
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									3,152		3,181		3,329
Operating revenues	766	757	717	912	770	838	694	879	3,152		3,181		3,329
Interest Expense									89		104		109
Depreciation and amortization									338		335		400
Income tax expense or benefit									98		96		132
Segment income									175		194		(441)
Net Income (Loss)	42	14	45	74	37	51	33	73	175		194		(441)
Capital investments, expenditures and acquisitions									514		499		446
Segment assets	10,560				10,939				10,560		10,939		11,024
Entity-wide revenue, major customer, percentage									36.00%		24.00%		13.00%
Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Operating revenues	626	718	685	688	625	718	620	659	2,717		2,622		2,520
Interest Expense									138		137		135
Depreciation and amortization									389		391		375
Income tax expense or benefit									(73)		74		156
Net Income (Loss)	59	(19)	77	(167)	55	(31)	68	76	(50)		168		285
Segment assets	10,008				10,062				10,008		10,062
U S Franchised Electric And Gas [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									16,042	[1]	10,586		10,563
Intersegment Revenues									38		33		34
Segment Reporting Information, Revenue for Reportable Segment, Total									16,080		10,619		10,597
Interest Expense									806		568		569
Depreciation and amortization									1,827		1,383		1,386
Equity in earnings of unconsolidated affiliates									(5)
Income tax expense or benefit									942		674		787
Segment income									1,744	[1],[2]	1,181	[3]	1,380
Capital investments, expenditures and acquisitions									4,220		3,717		3,891
Segment assets	98,162				47,977				98,162		47,977		45,210
Commercial Power [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									2,020		2,480		2,440
Intersegment Revenues									58		11		8
Segment Reporting Information, Revenue for Reportable Segment, Total									2,078		2,491		2,448
Interest Expense									63		87		68
Depreciation and amortization									228		230		225
Equity in earnings of unconsolidated affiliates									14		6		7
Income tax expense or benefit									(8)		(2)		22
Segment income									87		134	[4]	(327)	[5]
Capital investments, expenditures and acquisitions									1,038		492		525
Segment assets	6,992				6,939				6,992		6,939		6,704
International Energy [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									1,549		1,467		1,204
Segment Reporting Information, Revenue for Reportable Segment, Total									1,549		1,467		1,204
Interest Expense									77		47		71
Depreciation and amortization									99		90		86
Equity in earnings of unconsolidated affiliates									134		145		102
Income tax expense or benefit									149		196		143
Segment income									439		466		305
Capital investments, expenditures and acquisitions									551		114		181
Segment assets	5,406				4,539				5,406		4,539		4,310
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									19,611		14,533		14,207
Intersegment Revenues									96		44		42
Segment Reporting Information, Revenue for Reportable Segment, Total									19,707		14,577		14,249
Interest Expense									946		702		708
Depreciation and amortization									2,154		1,703		1,697
Equity in earnings of unconsolidated affiliates									143		151		109
Income tax expense or benefit									1,083		868		952
Segment income									2,270		1,781		1,358
Capital investments, expenditures and acquisitions									5,809		4,323		4,597
Segment assets	110,560				59,455				110,560		59,455		56,224
Total Reportable Segments [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									9,305		8,936		10,207
Intersegment Revenues									90		3		2
Segment Reporting Information, Revenue for Reportable Segment, Total									9,395		8,939		10,209
Interest Expense									459		423		444
Depreciation and amortization									727		683		905
Income tax expense or benefit									384		436		627
Segment income									727		853		1,045
Capital investments, expenditures and acquisitions									2,334		2,239		2,437
Segment assets	36,764				34,166				36,764		34,166		32,475
Total Reportable Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									3,152		3,181		3,329
Intersegment Revenues									52		4		5
Segment Reporting Information, Revenue for Reportable Segment, Total									3,204		3,185		3,334
Interest Expense									89		104		109
Depreciation and amortization									338		335		400
Income tax expense or benefit									116		104		146
Segment income									209		211		(422)
Capital investments, expenditures and acquisitions									514		499		446
Segment assets	10,609				11,033				10,609		11,033		11,079
All Other Segments [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									13		(4)		65
Intersegment Revenues									47		48		53
Segment Reporting Information, Revenue for Reportable Segment, Total									60		44		118
Interest Expense									296		157		132
Depreciation and amortization									135		103		89
Equity in earnings of unconsolidated affiliates									5		9		7
Income tax expense or benefit									(378)		(116)		(62)
Segment income									(538)	[6]	(76)	[7]	(41)	[8],[9]
Capital investments, expenditures and acquisitions									149		141		258
Segment assets	3,126				2,961				3,126		2,961		2,845
All Other Segments [Member] | Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Segment income									(169)		(46)
All Other Segments [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									12		12		16
Intersegment Revenues													0
Segment Reporting Information, Revenue for Reportable Segment, Total									12		12		16
Interest Expense									304		324		332
Depreciation and amortization									20		18		15
Income tax expense or benefit									(212)		(113)		(88)
Segment income									(379)	[10]	(273)	[11]	(185)
Capital investments, expenditures and acquisitions									32		17		32
Segment assets	684				765				684		765		450
All Other Segments [Member] | Progress Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Segment income									(139)		(18)
All Other Segments [Member] | Progress Energy Florida [Member]
Segment Reporting Information [Line Items]
Segment income									(58)		(16)
All Other Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Income tax expense or benefit									(18)		(8)		(14)
Segment income									(34)		(17)		(19)
Segment assets	117				259				117		259		192
All Other Segments [Member] | Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Segment income									(27)		(12)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues									(143)		(92)		(95)
Segment Reporting Information, Revenue for Reportable Segment, Total									(143)		(92)		(95)
Segment assets	170				110				170		110		21
Intersegment Eliminations [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues									(2)		(3)		(2)
Segment Reporting Information, Revenue for Reportable Segment, Total									(2)		(3)		(2)
Interest Expense									(23)		(22)		(29)
Capital investments, expenditures and acquisitions													(24)
Segment assets	(43)								(43)				(39)
Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									0		0		0
Intersegment Revenues									(52)		(4)		(5)
Segment Reporting Information, Revenue for Reportable Segment, Total									(52)		(4)		(5)
Segment assets	(166)				(353)				(166)		(353)		(247)
DEO Commercial Power [Member] | Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									1,407	[12]	1,707	[13]	1,706	[14]
Intersegment Revenues									51		4		5
Segment Reporting Information, Revenue for Reportable Segment, Total									1,458		1,711		1,711
Interest Expense									28		36		41
Depreciation and amortization									159		167		174
Income tax expense or benefit									25		6		40
Segment income									50		78	[15]	(361)	[16]
Capital investments, expenditures and acquisitions									87		124		93
Segment assets	4,175				4,740				4,175		4,740		4,821
Franchised Electric & Gas [Member] | Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									1,745		1,474		1,623
Intersegment Revenues									1
Segment Reporting Information, Revenue for Reportable Segment, Total									1,746		1,474		1,623
Interest Expense									61		68		68
Depreciation and amortization									179		168		226
Income tax expense or benefit									91		98		106
Segment income									159		133		(61)	[17]
Capital investments, expenditures and acquisitions									427		375		353
Segment assets	6,434				6,293				6,434		6,293		6,258
Franchised Electric [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Unaffiliated Revenues									9,305		8,936		10,207
Intersegment Revenues									90		3		2
Segment Reporting Information, Revenue for Reportable Segment, Total									9,395		8,939		10,209
Interest Expense									459		423		444
Depreciation and amortization									727		683		905
Income tax expense or benefit									384		436		627
Segment income									727	[18]	853	[19]	1,045
Capital investments, expenditures and acquisitions									2,334		2,239		2,437
Segment assets	$ 36,764				$ 34,166				$ 36,764		$ 34,166		$ 32,475

[1] On January 25, 2012 and January 27, 2012, the Duke Energy Carolinas' South Carolina and North Carolina rate case settlement agreements were approved by the PSCSC and NCUC, respectively. Among other things, the rate case settlements included an annual base rate increase of $309 million in North Carolina and a $93 million annual base rate increase in South Carolina, both beginning in February 2012. The impact of these rates impacts USFE&G. See Note 4 for additional information.

[2] USFE&G recorded after-tax impairment and other charges of $402 million, net of tax of $226 million, related to the Edwardsport integrated gasification combined cycle (IGCC) project. See Note 4 for additional information. USFE&G also recorded the reversal of expenses of $60 million, net of tax of $39 million, related to a prior year Voluntary Opportunity Plan in accordance with Duke Energy Carolinas' 2011 rate case. See Note 21 for additional information.

[3] USFE&G recorded an after-tax impairment charge of $135 million, net of tax of $87 million, related to the Edwardsport IGCC project. See Note 4 for additional information.

[4] Commercial Power recorded an after-tax impairment charge of $51 million, net of tax of $28 million, to write-down the carrying value of certain emission allowances. See Note 12 for additional information.

[5] Commercial Power recorded an impairment charge of $602 million, which consisted of a $500 million goodwill impairment charge associated with the nonregulated Midwest generating operations and a $102 million charge, net of tax of $58 million, to write-down the value of certain nonregulated Midwest generating assets and emission allowances primarily associated with these generation assets.

[6] Other includes after-tax costs to achieve the merger with Progress Energy of $397 million, net of tax of $239 million. See Note 2 for additional information.

[7] Other includes after-tax costs to achieve the merger with Progress Energy of $51 million, net of tax of $17 million. See Note 2 for additional information.

[8] Other includes expense of $105 million, net of tax of $67 million, related to the 2010 voluntary severance plan and the consolidation of certain corporate office functions from the Midwest to Charlotte, North Carolina. See Note 21 for additional information.

[9] Other recognized an $86 million gain, net of tax of $53 million, from the sale of a 50% ownership interest in DukeNet (See Note 2 for additional information), and $68 million gain, net of tax of $41 million, from the sale of an equity method investment in Q-Comm Corporation (Q-Comm). See Note 13 for additional information.

[10] Other includes after-tax costs to achieve the merger with Duke Energy of $198 million, net of tax of $127 million. See Note 2 for additional information.

[11] Other includes after-tax costs to achieve the merger with Duke Energy of $33 million, net of tax of $22 million. See Note 2 for additional information.

[12] Duke Energy Ohio earned approximately 36% of its consolidated operating revenues from PJM Settlements, Inc. in 2012, all of which is included in the Commercial Power segment. These revenues relate to the sale of capacity and electricity from Commercial Power's non-regulated generation assets.

[13] Duke Energy Ohio earned approximately 24% of its consolidated operating revenues from PJM Interconnection, LLC (PJM) in 2011, all of which is included in the Commercial Power segment. These revenues relate to the sale of capacity and electricity from Commercial Power's nonregulated generation assets.

[14] Duke Energy Ohio earned approximately 13% of its consolidated operating revenues from PJM in 2010, all of which is included in the Commercial Power segment. These revenues relate to the sale of capacity and electricity from Commercial Power's nonregulated generation assets.

[15] Commercial Power recorded an after-tax impairment charge of $51 million, net of tax of $28 million, during the year ended December 31, 2011, to write-down the carrying value of certain emission allowances. See Note 12 for additional information.

[16] Commercial Power recorded impairment charges of $621 million, which consisted of a $461 million goodwill impairment charge associated with the nonregulated Midwest generation operations and a $102 million charge, net of tax of $58 million, to write-down the value of certain nonregulated Midwest generating assets and emission allowances primarily associated with these generation assets.

[17] Franchised Electric and Gas recorded an impairment charge of $216 million related to the Ohio Transmission and Distribution reporting unit. This impairment charge was not applicable to Duke Energy as this reporting unit has a lower carrying value at Duke Energy.

[18] Franchised Electric recorded an $88 million impairment, net of tax of $58 million, related to the decision to retire Crystal River Unit 3 and a $60 million charge, net of tax of $40 million, to record a regulatory liability related to replacement power obligations as a result of the Crystal River Unit 3 outage. These charges were not applicable to Duke Energy as this reporting unit has a lower carrying value at Duke Energy. See Note 4 for additional information.

[19] Franchised Electric recorded a $173 million charge, net of tax of $115 million, for the amount to be refunded to customers through the fuel clause in accordance with the FPSC's 2012 settlement agreement. See Note 4 for additional information.