Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 1,714	$ 1,323	$ 1,085
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	2,026	1,994	1,846
Equity component of AFUDC	(260)	(234)	(153)
Asset impairment charges	335	726	420
Gains on sale of other assets	(19)	(268)	(44)
Impairment of goodwill and other long-lived assets	335	738	449
Deferred income taxes	602	741	941
Equity in earnings of unconsolidated affiliates	(160)	(116)	(70)
Contributions to qualified pension plans	(200)	(400)	(800)
Accrued pension and other post-retirement benefit costs	104	117	72
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(48)	15	4
Receivables	2	19	(38)
Inventory	(247)	198	(298)
Other current assets	185	227	277
Increase (decrease) in
Accounts payable	41	167	(80)
Taxes accrued	27	30	52
Other current liabilities	(254)	43	70
Other assets	12	157	144
Other liabilities	(188)	(240)	6
Net cash provided by operating activities	3,672	4,511	3,463
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(4,363)	(4,803)	(4,296)
Investment expenditures	(50)	(52)	(137)
Acquisitions	(51)		(124)
Purchases of available-for-sale securities	(3,194)	(2,166)	(3,013)
Proceeds from sales and maturities of available-for-sale securities	3,063	2,261	2,988
Net proceeds from the sales of other assets, and sales of and collections on notes receivable	118	406	70
Purchases of emission allowances	(9)	(14)	(93)
Sales of emission allowances	9	24	67
Change in restricted cash	22	(75)	58
Other	21	(4)	(12)
Net cash used in investing activities	(4,434)	(4,423)	(4,492)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	2,570	2,738	4,409
Proceeds from the issuance of common stock related to employee benefit plans	67	302	519
Payments for the redemption of long-term debt	(278)	(1,647)	(1,533)
Notes payable and commercial paper	208	(55)	(548)
Distributions to noncontrolling interests	(26)	(10)	(37)
Dividends paid	(1,329)	(1,284)	(1,222)
Other	(10)	(4)	(3)
Net cash provided by (used in) financing activities	1,202	40	1,585
Net increase (decrease) in cash and cash equivalents	440	128	556
Cash and cash equivalents at beginning of period	1,670	1,542	986
Cash and cash equivalents at end of period	2,110	1,670	1,542
Supplemental Disclosures
Cash paid for interest, net of amount capitalized	813	795	689
Cash paid (refunded) for income taxes	26	64	(419)
Significant non-cash transactions:
Accrued capital expenditures	409	361	428
Debt associated with the consolidation of variable interest entities		342
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	834	838	702
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	1,020	984	873
Equity component of AFUDC	(168)	(174)	(125)
Asset impairment charges	12
Gains on sale of other assets	(1)	(7)	(24)
Deferred income taxes	564	456	600
Contributions to qualified pension plans	(33)	(158)	(158)
Accrued pension and other post-retirement benefit costs	32	34	13
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(91)	1	1
Receivables	110	24	235
Inventory	(177)	134	(183)
Other current assets	144	(55)	44
Increase (decrease) in
Accounts payable	81	111	138
Taxes accrued	12	(23)	31
Other current liabilities	(170)	4	42
Other assets	(46)	19	(34)
Other liabilities	(249)	(158)	(230)
Net cash provided by operating activities	1,874	2,030	1,925
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(2,272)	(2,280)	(2,236)
Purchases of available-for-sale securities	(2,227)	(1,045)	(2,118)
Proceeds from sales and maturities of available-for-sale securities	2,179	1,066	2,094
Sales of emission allowances	2	7	23
Notes due from affiliate	(584)	250	(251)
Change in restricted cash	2	7	15
Other	(15)	(7)	(17)
Net cash used in investing activities	(2,915)	(2,002)	(2,490)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	1,498	692	904
Payments for the redemption of long-term debt	(7)	(607)	(511)
Capital contribution from parent			250
Distributions/Dividends to parent	(299)	(350)	3
Other	(15)	(4)	(7)
Net cash provided by (used in) financing activities	1,177	(269)	636
Net increase (decrease) in cash and cash equivalents	136	(241)	71
Cash and cash equivalents at beginning of period	153	394	323
Cash and cash equivalents at end of period	289	153	394
Supplemental Disclosures
Cash paid for interest, net of amount capitalized	337	342	312
Cash paid (refunded) for income taxes	(223)	69	(317)
Significant non-cash transactions:
Accrued capital expenditures	209	181	208
Allocation of net pension and other post-retirement assets from parent		146
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	194	(441)	(426)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	338	403	386
Asset impairment charges	89	837	769
Gains on sale of other assets	(5)	(3)	(12)
Impairment of goodwill and other long-lived assets	89	837	769
Deferred income taxes	190	17	102
Contributions to qualified pension plans	(48)	(45)	(210)
Accrued pension and other post-retirement benefit costs	14	12	13
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(8)	(18)	35
Receivables	108	(30)	(77)
Inventory	11	15	(16)
Other current assets	(24)	71	69
Increase (decrease) in
Accounts payable	(32)	(21)	8
Taxes accrued	8	25	18
Other current liabilities	(3)	6	(15)
Other assets	(61)	42	25
Other liabilities	47	(15)	24
Net cash provided by operating activities	818	855	693
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(499)	(446)	(433)
Purchases of emission allowances	(6)	(12)	(25)
Sales of emission allowances	7	13	37
Notes due from affiliate	79	(296)	(184)
Change in restricted cash	(26)		10
Other	(4)	1
Net cash used in investing activities	(449)	(740)	(595)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		34	813
Payments for the redemption of long-term debt	(9)	(36)	(103)
Notes payable and commercial paper		(12)	(279)
Notes payable to affiliate			(63)
Distributions/Dividends to parent	(485)		(360)
Other	(4)		(6)
Net cash provided by (used in) financing activities	(498)	(14)	2
Net increase (decrease) in cash and cash equivalents	(129)	101	100
Cash and cash equivalents at beginning of period	228	127	27
Cash and cash equivalents at end of period	99	228	127
Supplemental Disclosures
Cash paid for interest, net of amount capitalized	100	108	112
Cash paid (refunded) for income taxes	(102)	114	2
Significant non-cash transactions:
Accrued capital expenditures	43	40	64
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	168	285	201
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization (including amortization of nuclear fuel)	395	380	407
Equity component of AFUDC	(88)	(56)	(29)
Asset impairment charges	234	44
Gains on sale of other assets		2	4
Deferred income taxes	(63)	143	109
Contributions to qualified pension plans	(52)	(46)	(140)
Accrued pension and other post-retirement benefit costs	23	23	23
(Increase) decrease in
Receivables	88	(99)	31
Inventory	(64)	46	(96)
Other current assets	13	(14)	50
Increase (decrease) in
Accounts payable	(9)	(21)	(19)
Taxes accrued	29		(1)
Other current liabilities	(16)	17	(25)
Other assets	47	4	21
Other liabilities	(72)	(46)	(24)
Net cash provided by operating activities	633	662	512
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,066)	(1,255)	(1,029)
Purchases of available-for-sale securities	(11)	(24)	(73)
Proceeds from sales and maturities of available-for-sale securities	8	25	84
Purchases of emission allowances	(2)	(1)	(68)
Sales of emission allowances	1	3	7
Notes due from affiliate	115	(84)	90
Change in restricted cash	6	(6)	9
Other	(4)	(4)	(12)
Net cash used in investing activities	(953)	(1,346)	(992)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		571	949
Payments for the redemption of long-term debt	(14)	(199)	(728)
Capital contribution from parent		350	140
Notes payable to affiliate	300
Other	(4)	(4)	(5)
Net cash provided by (used in) financing activities	282	718	356
Net increase (decrease) in cash and cash equivalents	(38)	34	(124)
Cash and cash equivalents at beginning of period	54	20	144
Cash and cash equivalents at end of period	16	54	20
Supplemental Disclosures
Cash paid for interest, net of amount capitalized	130	122	141
Cash paid (refunded) for income taxes	90	31
Significant non-cash transactions:
Accrued capital expenditures	$ 110	$ 131	$ 150