Condensed Consolidated Statements of Operations (USD $) In Millions, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating Revenues
Regulated electric	$ 2,576	$ 2,531	$ 5,149	$ 5,156
Non-regulated electric, natural gas, and other	864	670	1,719	1,368
Regulated natural gas	94	86	329	357
Total operating revenues	3,534	3,287	7,197	6,881
Operating Expenses
Fuel used in electric generation and purchased power - regulated	834	789	1,646	1,608
Fuel used in electric generation and purchased power - non-regulated	388	282	764	560
Cost of natural gas and coal sold	63	46	214	236
Operation, maintenance and other	959	944	1,839	1,843
Depreciation and amortization	437	426	891	882
Property and other taxes	169	163	355	356
Goodwill and other impairment charges	9	656	9	656
Total operating expenses	2,859	3,306	5,718	6,141
Gains on Sales of Other Assets and Other, net	4	5	14	7
Operating Income (Loss)	679	(14)	1,493	747
Other Income and Expenses
Equity in earnings of unconsolidated affiliates	48	36	80	65
Gains on sales of unconsolidated affiliates	12		14
Other income and expenses, net	97	88	214	179
Total other income and expenses	157	124	308	244
Interest Expense	203	212	422	422
Income (Loss) From Continuing Operations Before Income Taxes	633	(102)	1,379	569
Income Tax Expense (Benefit) from Continuing Operations	192	116	425	342
Income (Loss) From Continuing Operations	441	(218)	954	227
Income From Discontinued Operations, net of tax		1		1
Net Income (Loss)	441	(217)	954	228
Less: Net Income Attributable to Noncontrolling Interests	6	5	8	5
Net Income (Loss) Attributable to Duke Energy Corporation	435	(222)	946	223
Income (loss) from continuing operations attributable to Duke Energy Corporation common shareholders
Basic	$ 0.33	$ (0.17)	$ 0.71	$ 0.17
Diluted	$ 0.33	$ (0.17)	$ 0.71	$ 0.17
Income from discontinued operations attributable to Duke Energy Corporation common shareholders
Basic
Diluted
Net income (loss) attributable to Duke Energy Corporation common shareholders
Basic	$ 0.33	$ (0.17)	$ 0.71	$ 0.17
Diluted	$ 0.33	$ (0.17)	$ 0.71	$ 0.17
Dividends declared per share	$ 0.495	$ 0.485	$ 0.74	$ 0.725
Weighted-average shares outstanding
Basic	1,332,000,000	1,314,000,000	1,331,000,000	1,312,000,000
Diluted	1,333,000,000	1,314,000,000	1,332,000,000	1,313,000,000
Duke Energy Carolinas [Member]
Operating Revenues
Regulated electric	1,607	1,513	3,159	3,058
Operating Expenses
Fuel used in electric generation and purchased power - regulated	511	458	980	912
Operation, maintenance and other	495	470	930	930
Depreciation and amortization	190	192	391	385
Property and other taxes	81	83	165	176
Total operating expenses	1,277	1,203	2,466	2,403
Gains on Sales of Other Assets and Other, net	1	3	1	5
Operating Income (Loss)	331	313	694	660
Other Income and Expenses
Other income and expenses, net	50	62	92	112
Interest Expense	82	86	171	176
Income (Loss) From Continuing Operations Before Income Taxes	299	289	615	596
Income Tax Expense (Benefit) from Continuing Operations	106	87	217	202
Net Income (Loss)	193	202	398	394
Duke Energy Ohio [Member]
Operating Revenues
Regulated electric	361	447	733	929
Non-regulated electric, natural gas, and other	239	115	510	339
Regulated natural gas	94	87	330	358
Total operating revenues	694	649	1,573	1,626
Operating Expenses
Fuel used in electric generation and purchased power - regulated	91	129	188	270
Fuel used in electric generation and purchased power - non-regulated	147	97	311	181
Cost of natural gas and coal sold	22	20	141	178
Operation, maintenance and other	215	200	420	386
Depreciation and amortization	88	93	176	203
Property and other taxes	63	58	136	133
Goodwill and other impairment charges	9	837	9	837
Total operating expenses	635	1,434	1,381	2,188
Gains on Sales of Other Assets and Other, net		4	2	3
Operating Income (Loss)	59	(781)	194	(559)
Other Income and Expenses
Other income and expenses, net	4	7	9	14
Interest Expense	27	28	51	58
Income (Loss) From Continuing Operations Before Income Taxes	36	(802)	152	(603)
Income Tax Expense (Benefit) from Continuing Operations	3	(43)	46	26
Net Income (Loss)	33	(759)	106	(629)
Duke Energy Indiana [Member]
Operating Revenues
Regulated electric	620	579	1,279	1,189
Operating Expenses
Fuel used in electric generation and purchased power - regulated	232	201	478	426
Operation, maintenance and other	163	171	324	314
Depreciation and amortization	97	85	197	186
Property and other taxes	19	13	41	33
Total operating expenses	511	470	1,040	959
Operating Income (Loss)	109	109	239	230
Other Income and Expenses
Other income and expenses, net	21	14	44	32
Interest Expense	34	34	70	67
Income (Loss) From Continuing Operations Before Income Taxes	96	89	213	195
Income Tax Expense (Benefit) from Continuing Operations	28	32	69	68
Net Income (Loss)	$ 68	$ 57	$ 144	$ 127