Condensed Consolidated Statements of Cash Flows (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 954	$ 228
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and Amortization	991	979
Equity component of AFUDC	(123)	(110)
Severance expense		98
Gains on sales of other assets and other, net	(27)	(8)
Impairment of goodwill and other long-lived assets	9	658
Deferred income taxes and investment tax credit amortization	461	245
Equity in earnings of unconsolidated affiliates	(80)	(65)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	13	6
Receivables	166	63
Inventory	(85)	217
Other current assets	128	40
Increase (decrease) in
Accounts payable	(338)	(124)
Taxes accrued	(99)	(43)
Other current liabilities	(179)	(121)
Other assets	81	117
Other liabilities	(155)	(56)
Net cash provided by operating activities	1,717	2,124
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,938)	(2,325)
Investment expenditures	(49)	(160)
Acquisitions	(4)
Purchases of available-for-sale securities	(1,266)	(1,232)
Proceeds from sales and maturities of available-for-sale securities	1,281	1,229
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	109	5
Purchases of emission allowances	(4)	(9)
Sales of emission allowances	7	17
Change in restricted cash	24	(37)
Other	2	4
Net cash used in investing activities	(1,838)	(2,508)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	499	1,363
Issuance of common stock related to employee benefit plans	10	112
Payments for the redemption of long-term debt	(82)	(948)
Notes payable and commercial paper	63	(16)
Distributions to noncontrolling interests	(18)	(5)
Dividends paid	(657)	(635)
Other	(2)	(19)
Net cash provided by (used in) financing activities	(187)	(148)
Net decrease in cash and cash equivalents	(308)	(532)
Cash and cash equivalents at beginning of period	1,670	1,542
Cash and cash equivalents at end of period	1,362	1,010
Significant non-cash transactions:
Accrued capital expenditures	317	353
Dividends declared but not paid	337	322
Debt associated with the consolidation of variable interest entities		342
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	398	394
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and Amortization	486	476
Equity component of AFUDC	(82)	(83)
Severance expense		64
Gains on sales of other assets and other, net	(1)	(5)
Deferred income taxes and investment tax credit amortization	311	145
Accrued pension and other post-retirement benefit costs	17	17
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	2
Receivables	143	(3)
Inventory	(43)	142
Other current assets	141	1
Increase (decrease) in
Accounts payable	(322)	(48)
Taxes accrued	(29)	(1)
Other current liabilities	(57)	(95)
Other assets	(18)	(1)
Other liabilities	(143)	(80)
Net cash provided by operating activities	803	923
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,070)	(1,190)
Purchases of available-for-sale securities	(767)	(640)
Proceeds from sales and maturities of available-for-sale securities	743	627
Sales of emission allowances	1	5
Notes due from affiliate	(211)	303
Change in restricted cash	2
Other	(7)	(4)
Net cash used in investing activities	(1,309)	(899)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	499	449
Payments for the redemption of long-term debt	(1)	(502)
Distribution to parent		(350)
Other	(2)	(2)
Net cash provided by (used in) financing activities	496	(405)
Net decrease in cash and cash equivalents	(10)	(381)
Cash and cash equivalents at beginning of period	153	394
Cash and cash equivalents at end of period	143	13
Significant non-cash transactions:
Accrued capital expenditures	140	134
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	106	(629)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and Amortization	177	204
Severance expense		21
Gains on sales of other assets and other, net	(2)	(3)
Impairment of goodwill and other long-lived assets	9	837
Deferred income taxes and investment tax credit amortization	85	(70)
Accrued pension and other post-retirement benefit costs	6	7
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	12	(2)
Receivables	124	71
Inventory	(4)	22
Other current assets	15	41
Increase (decrease) in
Accounts payable	(79)	(145)
Taxes accrued	(55)
Other current liabilities	(6)	(21)
Other assets	23	24
Other liabilities	(45)	(18)
Net cash provided by operating activities	366	339
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(230)	(189)
Purchases of emission allowances	(4)	(8)
Sales of emission allowances	6	9
Notes due from affiliate	86	(265)
Change in restricted cash	4
Other	(2)
Net cash used in investing activities	(140)	(453)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt		7
Payments for the redemption of long-term debt	(4)	(4)
Distribution to parent	(285)
Net cash provided by (used in) financing activities	(289)	3
Net decrease in cash and cash equivalents	(63)	(111)
Cash and cash equivalents at beginning of period	228	127
Cash and cash equivalents at end of period	165	16
Significant non-cash transactions:
Accrued capital expenditures	25	51
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	144	127
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and Amortization	200	189
Equity component of AFUDC	(39)	(23)
Severance expense		26
Deferred income taxes and investment tax credit amortization	39	69
Accrued pension and other post-retirement benefit costs	11	11
(Increase) decrease in
Receivables	89	(22)
Inventory	(31)	52
Other current assets	6	(31)
Increase (decrease) in
Accounts payable	(9)	(114)
Taxes accrued		(5)
Other current liabilities	(4)	(23)
Other assets	15	12
Other liabilities	(27)	(17)
Net cash provided by operating activities	394	251
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(512)	(644)
Purchases of available-for-sale securities	(2)	(12)
Proceeds from sales and maturities of available-for-sale securities	1	14
Purchases of emission allowances		(1)
Sales of emission allowances		3
Notes due from affiliate	85	15
Change in restricted cash	4	1
Other	(3)	(1)
Net cash used in investing activities	(427)	(625)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt		12
Payments for the redemption of long-term debt	(2)	(2)
Capital contribution from parent		350
Net cash provided by (used in) financing activities	(2)	360
Net decrease in cash and cash equivalents	(35)	(14)
Cash and cash equivalents at beginning of period	54	20
Cash and cash equivalents at end of period	19	6
Significant non-cash transactions:
Accrued capital expenditures	$ 143	$ 140