Condensed Consolidated Statements Of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009
Operating Revenues
Regulated electric	$ 10,589	$ 10,723		$ 10,033
Non-regulated electric, natural gas, and other	3,383	2,930		2,050
Regulated natural gas	557	619		648
Total operating revenues	14,529	14,272		12,731
Operating Expenses
Fuel used in electric generation and purchased power - regulated	3,309	3,345		3,246
Fuel used in electric generation and purchased power - non-regulated	1,488	1,199		765
Cost of natural gas and coal sold	348	381		433
Operation, maintenance and other	3,770	3,825		3,313
Depreciation and amortization	1,806	1,786		1,656
Property and other taxes	704	702		685
Goodwill and other impairment charges	335	726		420
Total operating expenses	11,760	11,964		10,518
(Losses) Gains on Sales of Other Assets and Other, net	8	153		36
Operating Income (Loss)	2,777	2,461		2,249
Other Income and Expenses
Equity in earnings of unconsolidated affiliates	160	116		70
(Losses) gains on sales of unconsolidated affiliates	11	103		(21)
Other income and expenses, net	376	370		284
Total other income and expenses	547	589		333
Interest Expense	859	840		751
Income (Loss) From Continuing Operations Before Income Taxes	2,465	2,210		1,831
Income Tax Expense (Benefit) from Continuing Operations	752	890		758
Income From Continuing Operations	1,713	1,320		1,073
Income From Discontinued Operations, net of tax	1	3		12
Net Income (Loss)	1,714	1,323		1,085
Less: Net (Loss) Income Attributable to Noncontrolling Interests	8	3		10
Net Income Attributable to Duke Energy Corporation	1,706	1,320		1,075
Income from continuing operations attributable to Duke Energy Corporation common shareholders
Basic	$ 1.28	$ 1.00		$ 0.82
Diluted	$ 1.28	$ 1.00		$ 0.82
Income from discontinued operations attributable to Duke Energy Corporation common shareholders
Basic				$ 0.01
Diluted				$ 0.01
Net income attributable to Duke Energy Corporation common shareholders
Basic	$ 1.28	$ 1.00	[1]	$ 0.83
Diluted	$ 1.28	$ 1.00	[1]	$ 0.83
Dividends declared per share	$ 0.99	$ 0.97		$ 0.94
Weighted-average shares outstanding
Basic	1,332	1,318		1,293
Diluted	1,333	1,319		1,294
Duke Energy Carolinas [Member]
Operating Revenues
Regulated electric	6,493	6,424		5,495
Operating Expenses
Fuel used in electric generation and purchased power - regulated	1,944	1,944		1,597
Operation, maintenance and other	1,904	1,907		1,609
Depreciation and amortization	814	787		692
Property and other taxes	340	348		334
Goodwill and other impairment charges	12
Total operating expenses	5,014	4,986		4,232
(Losses) Gains on Sales of Other Assets and Other, net	1	7		24
Operating Income (Loss)	1,480	1,445		1,287
Other Income and Expenses
Other income and expenses, net	186	212		122
Interest Expense	360	362		330
Income (Loss) From Continuing Operations Before Income Taxes	1,306	1,295		1,079
Income Tax Expense (Benefit) from Continuing Operations	472	457		377
Net Income (Loss)	834	838		702
Duke Energy Ohio [Member]
Operating Revenues
Regulated electric	1,518	1,823		2,236
Non-regulated electric, natural gas, and other	1,105	885		502
Regulated natural gas	558	621		650
Total operating revenues	3,181	3,329		3,388
Operating Expenses
Fuel used in electric generation and purchased power - regulated	380	490		772
Fuel used in electric generation and purchased power - non-regulated	653	465		274
Cost of natural gas and coal sold	209	269		329
Operation, maintenance and other	885	836		744
Depreciation and amortization	335	400		384
Property and other taxes	260	260		262
Goodwill and other impairment charges	89	837		769
Total operating expenses	2,811	3,557		3,534
(Losses) Gains on Sales of Other Assets and Other, net	5	3		12
Operating Income (Loss)	375	(225)		(134)
Other Income and Expenses
Other income and expenses, net	19	25		11
Interest Expense	104	109		117
Income (Loss) From Continuing Operations Before Income Taxes	290	(309)		(240)
Income Tax Expense (Benefit) from Continuing Operations	96	132		186
Net Income (Loss)	194	(441)		(426)
Duke Energy Indiana [Member]
Operating Revenues
Regulated electric	2,622	2,520		2,353
Operating Expenses
Fuel used in electric generation and purchased power - regulated	986	912		877
Operation, maintenance and other	647	611		573
Depreciation and amortization	391	375		403
Property and other taxes	82	70		73
Goodwill and other impairment charges	234	44
Total operating expenses	2,340	2,012		1,926
(Losses) Gains on Sales of Other Assets and Other, net		(2)		(4)
Operating Income (Loss)	282	506		423
Other Income and Expenses
Other income and expenses, net	97	70		38
Interest Expense	137	135		144
Income (Loss) From Continuing Operations Before Income Taxes	242	441		317
Income Tax Expense (Benefit) from Continuing Operations	74	156		116
Net Income (Loss)	$ 168	$ 285		$ 201

[1] Quarterly EPS amounts are meant to be stand-alone calculations and are not always additive to full-year amount due to rounding.