Condensed Consolidated Statements Of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 1,424	$ 894
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	1,508	1,481
Equity component of AFUDC	(193)	(173)
Severance expense		77
Impairment charges	309	700
Gains on sale of other assets	(19)	(10)
Impairment of goodwill and other long-lived assets	309	703
Deferred income taxes	526	527
Equity in earnings of unconsolidated affiliates	(123)	(86)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	37	44
Receivables	115	87
Inventory	(87)	289
Other current assets	248	123
Increase (decrease) in
Accounts payable	(455)	(100)
Taxes accrued	30	(76)
Other current liabilities	(172)	(94)
Other assets	91	30
Other liabilities	(212)	(55)
Net cash provided by operating activities	3,027	3,661
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(2,990)	(3,481)
Investment expenditures	(36)	(61)
Acquisitions	(50)
Purchases of available-for-sale securities	(2,409)	(1,742)
Proceeds from sales and maturities of available-for-sale securities	2,313	1,773
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	115	8
Purchases of emission allowances	(6)	(11)
Sales of emission allowances	8	20
Change in restricted cash	(19)	(29)
Other	4	(2)
Net cash used in investing activities	(3,070)	(3,525)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	1,015	2,450
Issuance of common stock related to employee benefit plans	13	215
Payments for the redemption of long-term debt	(179)	(1,599)
Notes payable and commercial paper	537	16
Distributions to noncontrolling interests	(19)	(5)
Dividends paid	(994)	(957)
Other	32	10
Net cash provided by (used in) financing activities	405	130
Net increase (decrease) in cash and cash equivalents	362	266
Cash and cash equivalents at beginning of period	1,670	1,542
Cash and cash equivalents at end of period	2,032	1,808
Significant non-cash transactions:
Accrued capital expenditures	276	524
Debt associated with the consolidation of variable interest entities		342
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	709	709
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	752	730
Equity component of AFUDC	(125)	(129)
Severance expense		61
Gains on sale of other assets	(2)	(7)
Deferred income taxes	498	260
Accrued pension and other post-retirement benefit costs	25	26
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	2
Receivables	96	(37)
Inventory	(25)	217
Other current assets	122	(1)
Increase (decrease) in
Accounts payable	(288)	42
Taxes accrued	18	4
Other current liabilities	(34)	(50)
Other assets	25	26
Other liabilities	(206)	(117)
Net cash provided by operating activities	1,567	1,734
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,604)	(1,737)
Purchases of available-for-sale securities	(1,598)	(871)
Proceeds from sales and maturities of available-for-sale securities	1,561	845
Sales of emission allowances	2	7
Notes due from affiliate	(250)	267
Change in restricted cash	2	7
Other	(9)	(8)
Net cash used in investing activities	(1,896)	(1,490)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	499	692
Payments for the redemption of long-term debt	(2)	(602)
Distributions/Dividends to parent		(350)
Other	(3)	(4)
Net cash provided by (used in) financing activities	494	(264)
Net increase (decrease) in cash and cash equivalents	165	(20)
Cash and cash equivalents at beginning of period	153	394
Cash and cash equivalents at end of period	318	374
Significant non-cash transactions:
Accrued capital expenditures	122	212
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	157	(453)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	261	301
Severance expense		23
Impairment charges	88	837
Gains on sale of other assets	(4)	(3)
Impairment of goodwill and other long-lived assets	88	837
Deferred income taxes	165	28
Accrued pension and other post-retirement benefit costs	11	11
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	15	(34)
Receivables	170	56
Inventory	(29)	1
Other current assets	(35)	66
Increase (decrease) in
Accounts payable	(150)	(217)
Taxes accrued	2	(2)
Other current liabilities	18	(17)
Other assets	9	15
Other liabilities	(55)	(31)
Net cash provided by operating activities	623	581
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(344)	(242)
Purchases of emission allowances	(5)	(10)
Sales of emission allowances	6	10
Notes due from affiliate	221	(113)
Change in restricted cash	(18)
Other	(3)
Net cash used in investing activities	(143)	(355)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		7
Payments for the redemption of long-term debt	(7)	(7)
Notes payable and commercial paper		(12)
Distributions/Dividends to parent	(485)
Net cash provided by (used in) financing activities	(492)	(12)
Net increase (decrease) in cash and cash equivalents	(12)	214
Cash and cash equivalents at beginning of period	228	127
Cash and cash equivalents at end of period	216	341
Significant non-cash transactions:
Accrued capital expenditures	18	92
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	113	219
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	301	285
Equity component of AFUDC	(64)	(40)
Severance expense		26
Impairment charges	222	44
Deferred income taxes	(67)	82
Accrued pension and other post-retirement benefit costs	16	18
(Increase) decrease in
Receivables	97	(2)
Inventory	(17)	66
Other current assets	18	8
Increase (decrease) in
Accounts payable	(35)	(98)
Taxes accrued	76	1
Other current liabilities	(9)	(21)
Other assets	19	4
Other liabilities	(47)	(38)
Net cash provided by operating activities	623	554
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(783)	(922)
Purchases of available-for-sale securities	(7)	(17)
Proceeds from sales and maturities of available-for-sale securities	5	19
Purchases of emission allowances		(1)
Sales of emission allowances	1	3
Notes due from affiliate	115	(160)
Change in restricted cash	6	(5)
Other	(3)
Net cash used in investing activities	(666)	(1,083)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		571
Payments for the redemption of long-term debt	(4)	(197)
Capital contribution from parent		350
Notes payable and commercial paper	14
Other		(3)
Net cash provided by (used in) financing activities	10	721
Net increase (decrease) in cash and cash equivalents	(33)	192
Cash and cash equivalents at beginning of period	54	20
Cash and cash equivalents at end of period	21	212
Significant non-cash transactions:
Accrued capital expenditures	$ 127	$ 155