Condensed Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 1,345,000,000	$ 1,424,000,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	1,865,000,000	1,508,000,000
Equity component of AFUDC	(209,000,000)	(193,000,000)
Severance expense, net	73,000,000	0
FERC Mitigation	117,000,000	0
Community support and charitable contributions expense	100,000,000	0
Gains on sales of other assets	(21,000,000)	(19,000,000)
Impairment of other long-lived assets	588,000,000	309,000,000
Deferred income taxes	437,000,000	526,000,000
Voluntary opportunity cost deferral	(101,000,000)	0
Equity in earnings of unconsolidated affiliates	(118,000,000)	(123,000,000)
Contributions to qualified pension plans	(79,000,000)	0
Accrued pension and other post-retirement benefit costs	152,000,000	78,000,000
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	68,000,000	37,000,000
Receivables	(83,000,000)	115,000,000
Inventory	(22,000,000)	(87,000,000)
Other current assets	101,000,000	248,000,000
Increase (decrease) in
Accounts payable	(222,000,000)	(455,000,000)
Taxes accrued	(7,000,000)	30,000,000
Other current liabilities	128,000,000	(172,000,000)
Other assets	(167,000,000)	91,000,000
Other liabilities	34,000,000	(290,000,000)
Net cash provided by operating activities	3,979,000,000	3,027,000,000
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(3,845,000,000)	(2,990,000,000)
Investment expenditures	(7,000,000)	(36,000,000)
Acquisitions	(36,000,000)	(50,000,000)
Cash Acquired from Acquisition	71,000,000	0
Purchases of available-for-sale securities	(2,159,000,000)	(2,409,000,000)
Proceeds from sales and maturities of available-for-sale securities	1,947,000,000	2,313,000,000
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	29,000,000	115,000,000
Change in restricted cash	(27,000,000)	(19,000,000)
Other	38,000,000	6,000,000
Net cash used in investing activities	(3,989,000,000)	(3,070,000,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	2,626,000,000	1,015,000,000
Proceeds from the issuance of common stock related to employee benefit plans	16,000,000	13,000,000
Payments for the redemption of long-term debt	(1,934,000,000)	(179,000,000)
Notes payable and commercial paper	98,000,000	537,000,000
Distributions to noncontrolling interests	(14,000,000)	(19,000,000)
Contributions from Noncontrolling Interests	76,000,000	0
Dividends paid	(1,211,000,000)	(994,000,000)
Other	4,000,000	32,000,000
Net cash used in financing activities	(339,000,000)	405,000,000
Net increase in cash and cash equivalents	(349,000,000)	362,000,000
Cash and cash equivalents at beginning of period	2,110,000,000	1,670,000,000
Cash and cash equivalents at end of period	1,761,000,000	2,032,000,000
Supplemental Disclosures
Fair Value of Assets Acquired	48,698,000,000
Liabilities assumed	30,627,000,000
Issuance of common stock	18,071,000,000
Accrued capital expenditures	407,000,000	276,000,000
Extinguishment of debt related to investment in Attiki Gas Supply, S.A.	66,000,000	0
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	735,000,000	709,000,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	860,000,000	752,000,000
Equity component of AFUDC	(116,000,000)	(125,000,000)
FERC Mitigation	46,000,000	0
Community support and charitable contributions expense	59,000,000	0
Gains on sales of other assets	(9,000,000)	(2,000,000)
Deferred income taxes	400,000,000	498,000,000
Voluntary opportunity cost deferral	(101,000,000)	0
Accrued pension and other post-retirement benefit costs	32,000,000	25,000,000
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	0	2,000,000
Receivables	(28,000,000)	7,000,000
Receivables from affiliated companies	0	89,000,000
Inventory	(62,000,000)	(25,000,000)
Other current assets	42,000,000	122,000,000
Increase (decrease) in
Accounts payable	(152,000,000)	(218,000,000)
Accounts payable to affiliated companies	(9,000,000)	(70,000,000)
Taxes accrued	16,000,000	18,000,000
Other current liabilities	202,000,000	(34,000,000)
Other assets	(53,000,000)	25,000,000
Other liabilities	(99,000,000)	(206,000,000)
Net cash provided by operating activities	1,763,000,000	1,567,000,000
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,453,000,000)	(1,604,000,000)
Purchases of available-for-sale securities	(672,000,000)	(1,598,000,000)
Proceeds from sales and maturities of available-for-sale securities	644,000,000	1,561,000,000
Notes receivable from affiliated companies	112,000,000	(250,000,000)
Change in restricted cash	0	2,000,000
Other	(6,000,000)	(7,000,000)
Net cash used in investing activities	(1,375,000,000)	(1,896,000,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	645,000,000	499,000,000
Payments for the redemption of long-term debt	(752,000,000)	(2,000,000)
Dividend to parent	(250,000,000)	0
Other	(6,000,000)	(3,000,000)
Net cash used in financing activities	(363,000,000)	494,000,000
Net increase in cash and cash equivalents	25,000,000	165,000,000
Cash and cash equivalents at beginning of period	289,000,000	153,000,000
Cash and cash equivalents at end of period	314,000,000	318,000,000
Supplemental Disclosures
Accrued capital expenditures	126,000,000	122,000,000
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	133,000,000	157,000,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	252,000,000	261,000,000
Gains on sales of other assets	(2,000,000)	(4,000,000)
Impairment of other long-lived assets	0	88,000,000
Deferred income taxes	78,000,000	165,000,000
Accrued pension and other post-retirement benefit costs	8,000,000	11,000,000
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	18,000,000	15,000,000
Receivables	40,000,000	163,000,000
Receivables from affiliated companies	51,000,000	7,000,000
Inventory	21,000,000	(29,000,000)
Other current assets	17,000,000	(35,000,000)
Increase (decrease) in
Accounts payable	(56,000,000)	(121,000,000)
Accounts payable to affiliated companies	(16,000,000)	(29,000,000)
Taxes accrued	(49,000,000)	2,000,000
Other current liabilities	(16,000,000)	18,000,000
Other assets	(39,000,000)	9,000,000
Other liabilities	(73,000,000)	(55,000,000)
Net cash provided by operating activities	367,000,000	623,000,000
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(386,000,000)	(344,000,000)
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	82,000,000	0
Notes receivable from affiliated companies	317,000,000	221,000,000
Change in restricted cash	(46,000,000)	(18,000,000)
Other	1,000,000	(2,000,000)
Net cash used in investing activities	(32,000,000)	(143,000,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments for the redemption of long-term debt	(507,000,000)	(7,000,000)
Notes payable to affiliated companies	86,000,000	0
Dividend to parent	0	(485,000,000)
Net cash used in financing activities	(421,000,000)	(492,000,000)
Net increase in cash and cash equivalents	(86,000,000)	(12,000,000)
Cash and cash equivalents at beginning of period	99,000,000	228,000,000
Cash and cash equivalents at end of period	13,000,000	216,000,000
Supplemental Disclosures
Accrued capital expenditures	26,000,000	18,000,000
Transfer of Vermillion Generating Station	(28,000,000)
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	(109,000,000)	113,000,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	296,000,000	301,000,000
Equity component of AFUDC	(61,000,000)	(64,000,000)
Impairment of other long-lived assets	580,000,000	222,000,000
Deferred income taxes	(97,000,000)	(67,000,000)
Accrued pension and other post-retirement benefit costs	12,000,000	16,000,000
(Increase) decrease in
Receivables	16,000,000	93,000,000
Receivables from affiliated companies	23,000,000	4,000,000
Inventory	(26,000,000)	(17,000,000)
Other current assets	5,000,000	18,000,000
Increase (decrease) in
Accounts payable	20,000,000	(22,000,000)
Accounts payable to affiliated companies	(20,000,000)	(13,000,000)
Taxes accrued	(35,000,000)	76,000,000
Other current liabilities	(7,000,000)	(9,000,000)
Other assets	15,000,000	19,000,000
Other liabilities	(28,000,000)	(47,000,000)
Net cash provided by operating activities	584,000,000	623,000,000
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(582,000,000)	(783,000,000)
Purchases of available-for-sale securities	(12,000,000)	(7,000,000)
Proceeds from sales and maturities of available-for-sale securities	14,000,000	5,000,000
Notes receivable from affiliated companies	0	115,000,000
Change in restricted cash	0	6,000,000
Other	(1,000,000)	(2,000,000)
Net cash used in investing activities	(581,000,000)	(666,000,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	250,000,000	0
Payments for the redemption of long-term debt	(4,000,000)	(4,000,000)
Notes payable to affiliated companies	(245,000,000)	14,000,000
Other	(2,000,000)	0
Net cash used in financing activities	(1,000,000)	10,000,000
Net increase in cash and cash equivalents	2,000,000	(33,000,000)
Cash and cash equivalents at beginning of period	16,000,000	54,000,000
Cash and cash equivalents at end of period	18,000,000	21,000,000
Supplemental Disclosures
Accrued capital expenditures	37,000,000	127,000,000
Transfer of Vermillion Generating Station	$ 26,000,000	$ 0