Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 747	$ 954
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	1,077	991
Equity component of AFUDC	(116)	(123)
Gains on sales of other assets	(7)	(27)
Impairment of other long-lived assets	408	9
Deferred income taxes	230	461
Voluntary opportunity cost deferral	(101)	0
Equity in earnings of unconsolidated affiliates	(85)	(80)
Accrued pension and other post-retirement benefit costs	57	52
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(10)	13
Receivables	61	166
Inventory	(165)	(85)
Other current assets	105	128
Increase (decrease) in
Accounts payable	(102)	(338)
Taxes accrued	(67)	(99)
Other current liabilities	34	(179)
Other assets	22	81
Other liabilities	(86)	(207)
Net cash provided by operating activities	2,002	1,717
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(2,252)	(1,938)
Investment expenditures	(9)	(49)
Acquisitions	(36)	(4)
Purchases of available-for-sale securities	(1,240)	(1,266)
Proceeds from sales and maturities of available-for-sale securities	1,155	1,281
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	23	109
Change in restricted cash	(51)	24
Other	19	5
Net cash used in investing activities	(2,391)	(1,838)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	721	499
Proceeds from the issuance of common stock related to employee benefit plans	14	10
Payments for the redemption of long-term debt	(878)	(82)
Notes payable and commercial paper	631	63
Distributions to noncontrolling interests	(5)	(18)
Dividends paid	(670)	(657)
Other	(8)	(2)
Net cash used in financing activities	(195)	(187)
Net increase in cash and cash equivalents	(584)	(308)
Cash and cash equivalents at beginning of period	2,110	1,670
Cash and cash equivalents at end of period	1,526	1,362
Supplemental Disclosures
Accrued capital expenditures	216	317
Dividends declared but not paid	344	337
Extinguishment of debt related to investment in Attiki Gas Supply, S.A.	66	0
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	477	398
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	569	486
Equity component of AFUDC	(74)	(82)
Gains on sales of other assets	(6)	(1)
Deferred income taxes	275	311
Voluntary opportunity cost deferral	(101)	0
Accrued pension and other post-retirement benefit costs	21	17
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	1	2
Receivables	53	143
Inventory	(99)	(43)
Other current assets	8	141
Increase (decrease) in
Accounts payable	(244)	(322)
Taxes accrued	(17)	(29)
Other current liabilities	76	(57)
Other assets	(40)	(18)
Other liabilities	(74)	(143)
Net cash provided by operating activities	825	803
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,006)	(1,070)
Purchases of available-for-sale securities	(607)	(767)
Proceeds from sales and maturities of available-for-sale securities	591	743
Notes due from affiliate	679	(211)
Change in restricted cash	0	2
Other	(1)	(6)
Net cash used in investing activities	(344)	(1,309)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	0	499
Payments for the redemption of long-term debt	(751)	(1)
Other	(1)	(2)
Net cash used in financing activities	(752)	496
Net increase in cash and cash equivalents	(271)	(10)
Cash and cash equivalents at beginning of period	289	153
Cash and cash equivalents at end of period	18	143
Supplemental Disclosures
Accrued capital expenditures	104	140
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	119	106
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	165	177
Gains on sales of other assets	(2)	(2)
Impairment of other long-lived assets	0	9
Deferred income taxes	69	85
Accrued pension and other post-retirement benefit costs	6	6
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(11)	12
Receivables	51	124
Inventory	(20)	(4)
Other current assets	29	15
Increase (decrease) in
Accounts payable	(33)	(79)
Taxes accrued	(22)	(55)
Other current liabilities	(14)	(6)
Other assets	(11)	23
Other liabilities	(75)	(45)
Net cash provided by operating activities	251	366
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(252)	(230)
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	82	0
Notes due from affiliate	(130)	86
Change in restricted cash	(25)	4
Other	1	0
Net cash used in investing activities	(324)	(140)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments for the redemption of long-term debt	(4)	(4)
Dividend to parent	0	(285)
Net cash used in financing activities	(4)	(289)
Net increase in cash and cash equivalents	(77)	(63)
Cash and cash equivalents at beginning of period	99	228
Cash and cash equivalents at end of period	22	165
Supplemental Disclosures
Accrued capital expenditures	37	25
Transfer of Vermillion Generating Station	(28)
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	(90)	144
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	195	200
Equity component of AFUDC	(39)	(39)
Impairment of other long-lived assets	400	0
Deferred income taxes	(73)	39
Accrued pension and other post-retirement benefit costs	8	11
(Increase) decrease in
Receivables	8	89
Inventory	(28)	(31)
Other current assets	19	6
Increase (decrease) in
Accounts payable	0	(9)
Taxes accrued	(25)	0
Other current liabilities	17	(4)
Other assets	26	15
Other liabilities	(35)	(27)
Net cash provided by operating activities	383	394
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(439)	(512)
Purchases of available-for-sale securities	(8)	(2)
Proceeds from sales and maturities of available-for-sale securities	10	1
Notes due from affiliate	0	85
Change in restricted cash	0	4
Other	(2)	(3)
Net cash used in investing activities	(439)	(427)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	250	0
Payments for the redemption of long-term debt	(2)	(2)
Notes payable to affiliate	(187)	0
Other	(2)	0
Net cash used in financing activities	59	(2)
Net increase in cash and cash equivalents	3	(35)
Cash and cash equivalents at beginning of period	16	54
Cash and cash equivalents at end of period	19	19
Supplemental Disclosures
Accrued capital expenditures	46	143
Transfer of Vermillion Generating Station	$ 26	$ 0