Condensed Consolidating Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Operating revenues
Regulated electric	$ 2,775	$ 2,743	$ 7,135	$ 7,161
Non-regulated electric and other	13	10	43	35
Total operating revenues	2,788	2,753	7,178	7,196
Operating expenses
Fuel used in electric generation and purchased power	1,396	1,234	3,299	3,186
Operation, maintenance and other	626	494	1,798	1,500
Depreciation and amortization	174	175	571	508
Property and other taxes	160	164	440	437
Impairment charges	55	0	55	0
Total operating expenses	2,411	2,067	6,163	5,631
Gains on sales of other assets and other, net	2	1	4	2
Operating (loss) income	379	687	1,019	1,567
Other income and expenses, net	32	(44)	97	21
Interest expense, net	182	172	560	542
Income (Loss) from Continuing Operations before Income Taxes	229	471	556	1,046
Income tax expense from continuing operations	75	178	193	386
Income from continuing operations	154	293	363	660
Income (loss) from discontinued operations, net of tax	3	0	10	(4)
Net income (loss)	157	293	373	656
Less: net income attributable to noncontrolling interests	2	2	5	5
Net income attributable to Duke Energy Corporation	155	291	368	651
Comprehensive income, net of tax
Comprehensive income	255	228	472	574
Comprehensive income attributable to noncontrolling interests, net of tax	(2)	(2)	(5)	(5)
Comprehensive income attributable to Duke Energy Corporation	253	226	467	569
Current assets
Cash and cash equivalents	57	103	57	103
Receivables	930		930		883
Notes receivable from affiliated companies	0		0		0
Inventory	1,366		1,366		1,429
Prepayments and other current assets	673		673		778
Total current assets	3,026		3,026		3,320
Investments and other assets
Nuclear decommissioning trust funds	1,844		1,844		1,647
Investment in consolidated subsidiaries	0		0		0
Goodwill	3,655		3,655		3,655
Other	532		532		504
Total investments and other assets	6,031		6,031		5,806
Net property, plant and equipment	24,167		24,167		22,292
Regulatory assets and deferred debits
Regulatory assets	3,331		3,331		3,424
Other	96		96		89
Total regulatory assets and deferred debits	3,427		3,427		3,513
Total assets	36,651		36,651		34,931
Current liabilities
Notes payable and commercial paper	0		0		671
Current maturities of long-term debt	838		838		961
Notes payable to affiliated companies	635		635		0
Other	2,263		2,263		2,387
Total current liabilities	3,736		3,736		4,019
Long-term debt	12,664		12,664		11,918
Long-term debt, affiliate	274		274		273
Deferred credits and other liabilities
Deferred income taxes	2,509		2,509		2,193
Asset retirement obligations	2,137		2,137		1,265
Regulatory liabilities	2,704		2,704		2,727
Deferred credits and other liabilities	2,381		2,381		2,418
Total deferred credits and other liabilities	9,731		9,731		8,603
Preferred stock of subsidiaries	93		93		93
Equity
Common shareholders' equity	10,150		10,150		10,021
Noncontrolling interests	3		3		4
Total equity	10,153	10,115	10,153	10,115	10,025	10,027
Total liabilities and equity	36,651		36,651		34,931
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			1,450	1,258
Cash flows from investing activities
Capital expenditures			(1,695)	(1,647)
Purchases of available-for-sale securities			(947)	(4,537)
Proceeds from sales and maturities of available-for-sale securities			921	4,509
Other			112	100
Net cash provided (used) by investing activities			(1,609)	(1,575)
Cash flows from financing activities
Issuance of long-term debt			1,432	1,286
Issuance of common stock related to employee benefit plans			6	42
Payments for the redemption of long-term debt			(961)	(1,010)
Notes payable and commercial paper			(671)	45
Distributions to noncontrolling interests			(6)	(6)
Dividends paid			(445)	(550)
Notes payable to affiliate			635	0
Other			(4)	2
Net cash provided (used) by financing activities			(14)	(191)
Net increase (decrease) in cash and cash equivalents			(173)	(508)
Cash and cash equivalents at beginning of period			230	611
Cash and cash equivalents at end of period	57	103	57	103
Parent [Member]
Operating revenues
Regulated electric	0	0	0	0
Non-regulated electric and other	0	0	0	0
Total operating revenues	0	0	0	0
Operating expenses
Fuel used in electric generation and purchased power	0	0	0	0
Operation, maintenance and other	0	2	4	6
Depreciation and amortization	0	0	0	0
Property and other taxes	0	0	0	0
Impairment charges	0	0	0	0
Total operating expenses	0	2	4	6
Gains on sales of other assets and other, net	0	0	0	0
Operating (loss) income	0	(2)	(4)	(6)
Equity in earnings of consolidated subsidiaries	203	391	489	832
Other income and expenses, net	(1)	(63)	8	(59)
Interest expense, net	63	80	193	216
Income (Loss) from Continuing Operations before Income Taxes	139	246	300	551
Income tax expense from continuing operations	(16)	(45)	(68)	(100)
Income from continuing operations	155	291	368	651
Income (loss) from discontinued operations, net of tax	0	0	0	0
Net income (loss)	155	291	368	651
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Duke Energy Corporation	155	291	368	651
Comprehensive income, net of tax
Comprehensive income	253	226	467	569
Comprehensive income attributable to noncontrolling interests, net of tax	0	0	0	0
Comprehensive income attributable to Duke Energy Corporation	253	226	467	569
Current assets
Cash and cash equivalents	0	0	0	0
Receivables	0		0		0
Notes receivable from affiliated companies	676		676		53
Inventory	0		0		0
Prepayments and other current assets	59		59		127
Total current assets	735		735		297
Investments and other assets
Nuclear decommissioning trust funds	0		0		0
Investment in consolidated subsidiaries	14,171		14,171		14,043
Goodwill	0		0		0
Other	151		151		118
Total investments and other assets	14,322		14,322		14,161
Net property, plant and equipment	0		0		0
Regulatory assets and deferred debits
Regulatory assets	0		0		0
Other	23		23		22
Total regulatory assets and deferred debits	23		23		22
Total assets	15,080		15,080		14,480
Current liabilities
Notes payable and commercial paper	0		0		250
Current maturities of long-term debt	0		0		450
Notes payable to affiliated companies	843		843		0
Other	75		75		199
Total current liabilities	918		918		899
Long-term debt	3,992		3,992		3,543
Long-term debt, affiliate	0		0		0
Deferred credits and other liabilities
Deferred income taxes	0		0		0
Asset retirement obligations	0		0		0
Regulatory liabilities	0		0		0
Deferred credits and other liabilities	20		20		17
Total deferred credits and other liabilities	20		20		17
Preferred stock of subsidiaries	0		0		0
Equity
Common shareholders' equity	10,150		10,150		10,021
Noncontrolling interests	0		0		0
Total equity	10,150		10,150		10,021
Total liabilities and equity	15,080		15,080		14,480
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			335	659
Cash flows from investing activities
Capital expenditures			0	0
Purchases of available-for-sale securities			0	0
Proceeds from sales and maturities of available-for-sale securities			0	0
Notes due from affiliate			(624)	(83)
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	(11)
Other			24	(6)
Net cash provided (used) by investing activities			(600)	(100)
Cash flows from financing activities
Issuance of long-term debt			444	494
Issuance of common stock related to employee benefit plans			6	42
Payments for the redemption of long-term debt			(450)	(700)
Notes payable and commercial paper			(250)	45
Distributions to noncontrolling interests			0	0
Dividends paid			(445)	(550)
Dividends to parent			0	0
Dividends paid to parent in excess of retained earnings			0	0
Notes payable to affiliate			843	0
Contributions from parent			0	0
Other			0	0
Net cash provided (used) by financing activities			148	(669)
Net increase (decrease) in cash and cash equivalents			(117)	(110)
Cash and cash equivalents at beginning of period			117	110
Cash and cash equivalents at end of period	0	0	0	0
Subsidiary Guarantor [Member]
Operating revenues
Regulated electric	1,382	1,414	3,576	3,639
Non-regulated electric and other	10	9	26	24
Total operating revenues	1,392	1,423	3,602	3,663
Operating expenses
Fuel used in electric generation and purchased power	799	690	1,849	1,804
Operation, maintenance and other	247	225	668	659
Depreciation and amortization	39	39	158	112
Property and other taxes	100	106	272	274
Impairment charges	0	0	0	0
Total operating expenses	1,185	1,060	2,947	2,849
Gains on sales of other assets and other, net	1	1	2	2
Operating (loss) income	208	364	657	816
Equity in earnings of consolidated subsidiaries	0	0	0	0
Other income and expenses, net	12	2	32	25
Interest expense, net	67	52	210	193
Income (Loss) from Continuing Operations before Income Taxes	153	314	479	648
Income tax expense from continuing operations	55	116	177	240
Income from continuing operations	98	198	302	408
Income (loss) from discontinued operations, net of tax	2	1	10	(2)
Net income (loss)	100	199	312	406
Less: net income attributable to noncontrolling interests	1	1	3	3
Net income attributable to Duke Energy Corporation	99	198	309	403
Comprehensive income, net of tax
Comprehensive income	118	182	331	384
Comprehensive income attributable to noncontrolling interests, net of tax	(1)	(1)	(3)	(3)
Comprehensive income attributable to Duke Energy Corporation	117	181	328	381
Current assets
Cash and cash equivalents	38	34	38	34
Receivables	435		435		367
Notes receivable from affiliated companies	0		0		0
Inventory	618		618		659
Prepayments and other current assets	417		417		418
Total current assets	1,508		1,508		1,536
Investments and other assets
Nuclear decommissioning trust funds	621		621		559
Investment in consolidated subsidiaries	0		0		0
Goodwill	0		0		0
Other	232		232		189
Total investments and other assets	853		853		748
Net property, plant and equipment	10,885		10,885		10,455
Regulatory assets and deferred debits
Regulatory assets	1,446		1,446		1,629
Other	49		49		51
Total regulatory assets and deferred debits	1,495		1,495		1,680
Total assets	14,741		14,741		14,419
Current liabilities
Notes payable and commercial paper	0		0		233
Current maturities of long-term debt	435		435		10
Notes payable to affiliated companies	431		431		238
Other	1,120		1,120		1,030
Total current liabilities	1,986		1,986		1,511
Long-term debt	4,237		4,237		4,671
Long-term debt, affiliate	309		309		309
Deferred credits and other liabilities
Deferred income taxes	960		960		757
Asset retirement obligations	514		514		369
Regulatory liabilities	880		880		1,024
Deferred credits and other liabilities	923		923		1,012
Total deferred credits and other liabilities	3,277		3,277		3,162
Preferred stock of subsidiaries	34		34		34
Equity
Common shareholders' equity	4,895		4,895		4,728
Noncontrolling interests	3		3		4
Total equity	4,898		4,898		4,732
Total liabilities and equity	14,741		14,741		14,419
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			733	664
Cash flows from investing activities
Capital expenditures			(573)	(626)
Purchases of available-for-sale securities			(562)	(4,099)
Proceeds from sales and maturities of available-for-sale securities			561	4,101
Notes due from affiliate			0	22
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	0
Other			13	102
Net cash provided (used) by investing activities			(561)	(500)
Cash flows from financing activities
Issuance of long-term debt			0	296
Issuance of common stock related to employee benefit plans			0	0
Payments for the redemption of long-term debt			(9)	(309)
Notes payable and commercial paper			(233)	0
Distributions to noncontrolling interests			(3)	(4)
Dividends paid			0	0
Dividends to parent			(173)	(478)
Dividends paid to parent in excess of retained earnings			0	0
Notes payable to affiliate			193	84
Contributions from parent			0	10
Other			(1)	1
Net cash provided (used) by financing activities			(226)	(400)
Net increase (decrease) in cash and cash equivalents			(54)	(236)
Cash and cash equivalents at beginning of period			92	270
Cash and cash equivalents at end of period	38	34	38	34
Non-Guarantor Subsidiaries [Member]
Operating revenues
Regulated electric	1,394	1,330	3,561	3,524
Non-regulated electric and other	4	2	17	11
Total operating revenues	1,398	1,332	3,578	3,535
Operating expenses
Fuel used in electric generation and purchased power	597	544	1,450	1,382
Operation, maintenance and other	378	265	1,120	829
Depreciation and amortization	135	136	413	396
Property and other taxes	63	58	175	168
Impairment charges	55	0	55	0
Total operating expenses	1,228	1,003	3,213	2,775
Gains on sales of other assets and other, net	1	0	2	0
Operating (loss) income	171	329	367	760
Equity in earnings of consolidated subsidiaries	0	0	0	0
Other income and expenses, net	23	14	58	54
Interest expense, net	53	41	157	134
Income (Loss) from Continuing Operations before Income Taxes	141	302	268	680
Income tax expense from continuing operations	43	103	88	243
Income from continuing operations	98	199	180	437
Income (loss) from discontinued operations, net of tax	1	(1)	0	(2)
Net income (loss)	99	198	180	435
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Duke Energy Corporation	99	198	180	435
Comprehensive income, net of tax
Comprehensive income	170	165	250	393
Comprehensive income attributable to noncontrolling interests, net of tax	0	0	0	0
Comprehensive income attributable to Duke Energy Corporation	170	165	250	393
Current assets
Cash and cash equivalents	19	69	19	69
Receivables	495		495		516
Notes receivable from affiliated companies	209		209		219
Inventory	749		749		770
Prepayments and other current assets	293		293		297
Total current assets	1,765		1,765		1,823
Investments and other assets
Nuclear decommissioning trust funds	1,223		1,223		1,088
Investment in consolidated subsidiaries	0		0		0
Goodwill	0		0		0
Other	695		695		675
Total investments and other assets	1,918		1,918		1,763
Net property, plant and equipment	13,126		13,126		11,677
Regulatory assets and deferred debits
Regulatory assets	1,885		1,885		1,795
Other	30		30		22
Total regulatory assets and deferred debits	1,915		1,915		1,817
Total assets	18,724		18,724		17,080
Current liabilities
Notes payable and commercial paper	0		0		188
Current maturities of long-term debt	403		403		502
Notes payable to affiliated companies	246		246		34
Other	1,164		1,164		1,221
Total current liabilities	1,813		1,813		1,945
Long-term debt	4,435		4,435		3,704
Long-term debt, affiliate	0		0		0
Deferred credits and other liabilities
Deferred income taxes	2,091		2,091		1,903
Asset retirement obligations	1,623		1,623		896
Regulatory liabilities	1,667		1,667		1,543
Deferred credits and other liabilities	1,432		1,432		1,384
Total deferred credits and other liabilities	6,813		6,813		5,726
Preferred stock of subsidiaries	59		59		59
Equity
Common shareholders' equity	5,604		5,604		5,646
Noncontrolling interests	0		0		0
Total equity	5,604		5,604		5,646
Total liabilities and equity	18,724		18,724		17,080
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			865	863
Cash flows from investing activities
Capital expenditures			(1,122)	(1,021)
Purchases of available-for-sale securities			(385)	(438)
Proceeds from sales and maturities of available-for-sale securities			359	408
Notes due from affiliate			10	(23)
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	0
Other			75	5
Net cash provided (used) by investing activities			(1,063)	(1,069)
Cash flows from financing activities
Issuance of long-term debt			988	496
Issuance of common stock related to employee benefit plans			0	0
Payments for the redemption of long-term debt			(502)	(1)
Notes payable and commercial paper			(188)	0
Distributions to noncontrolling interests			0	0
Dividends paid			0	0
Dividends to parent			(310)	(450)
Dividends paid to parent in excess of retained earnings			0	0
Notes payable to affiliate			212	0
Contributions from parent			0	1
Other			(4)	(2)
Net cash provided (used) by financing activities			196	44
Net increase (decrease) in cash and cash equivalents			(2)	(162)
Cash and cash equivalents at beginning of period			21	231
Cash and cash equivalents at end of period	19	69	19	69
Other [Member]
Operating revenues
Regulated electric	(1)	(1)	(2)	(2)
Non-regulated electric and other	(1)	(1)	0	0
Total operating revenues	(2)	(2)	(2)	(2)
Operating expenses
Fuel used in electric generation and purchased power	0	0	0	0
Operation, maintenance and other	1	2	6	6
Depreciation and amortization	0	0	0	0
Property and other taxes	(3)	0	(7)	(5)
Impairment charges	0	0	0	0
Total operating expenses	(2)	2	(1)	1
Gains on sales of other assets and other, net	0	0	0	0
Operating (loss) income	0	(4)	(1)	(3)
Equity in earnings of consolidated subsidiaries	(203)	(391)	(489)	(832)
Other income and expenses, net	(2)	3	(1)	1
Interest expense, net	(1)	(1)	0	(1)
Income (Loss) from Continuing Operations before Income Taxes	(204)	(391)	(491)	(833)
Income tax expense from continuing operations	(7)	4	(4)	3
Income from continuing operations	(197)	(395)	(487)	(836)
Income (loss) from discontinued operations, net of tax	0	0	0	0
Net income (loss)	(197)	(395)	(487)	(836)
Less: net income attributable to noncontrolling interests	1	1	2	2
Net income attributable to Duke Energy Corporation	(198)	(396)	(489)	(838)
Comprehensive income, net of tax
Comprehensive income	(286)	(345)	(576)	(772)
Comprehensive income attributable to noncontrolling interests, net of tax	(1)	(1)	(2)	(2)
Comprehensive income attributable to Duke Energy Corporation	(287)	(346)	(578)	(774)
Current assets
Cash and cash equivalents	0	0	0	0
Receivables	0		0		0
Notes receivable from affiliated companies	(885)		(885)		(272)
Inventory	(1)		(1)		0
Prepayments and other current assets	(96)		(96)		(64)
Total current assets	(982)		(982)		(336)
Investments and other assets
Nuclear decommissioning trust funds	0		0		0
Investment in consolidated subsidiaries	(14,171)		(14,171)		(14,043)
Goodwill	3,655		3,655		3,655
Other	(546)		(546)		(478)
Total investments and other assets	(11,062)		(11,062)		(10,866)
Net property, plant and equipment	156		156		160
Regulatory assets and deferred debits
Regulatory assets	0		0		0
Other	(6)		(6)		(6)
Total regulatory assets and deferred debits	(6)		(6)		(6)
Total assets	(11,894)		(11,894)		(11,048)
Current liabilities
Notes payable and commercial paper	0		0		0
Current maturities of long-term debt	0		0		(1)
Notes payable to affiliated companies	(885)		(885)		(272)
Other	(96)		(96)		(63)
Total current liabilities	(981)		(981)		(336)
Long-term debt	0		0		0
Long-term debt, affiliate	(35)		(35)		(36)
Deferred credits and other liabilities
Deferred income taxes	(542)		(542)		(467)
Asset retirement obligations	0		0		0
Regulatory liabilities	157		157		160
Deferred credits and other liabilities	6		6		5
Total deferred credits and other liabilities	(379)		(379)		(302)
Preferred stock of subsidiaries	0		0		0
Equity
Common shareholders' equity	(10,499)		(10,499)		(10,374)
Noncontrolling interests	0		0		0
Total equity	(10,499)		(10,499)		(10,374)
Total liabilities and equity	(11,894)		(11,894)		(11,048)
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			(483)	(928)
Cash flows from investing activities
Capital expenditures			0	0
Purchases of available-for-sale securities			0	0
Proceeds from sales and maturities of available-for-sale securities			1	0
Notes due from affiliate			614	84
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	11
Other			0	(1)
Net cash provided (used) by investing activities			615	94
Cash flows from financing activities
Issuance of long-term debt			0	0
Issuance of common stock related to employee benefit plans			0	0
Payments for the redemption of long-term debt			0	0
Notes payable and commercial paper			0	0
Distributions to noncontrolling interests			(3)	(2)
Dividends paid			0	0
Dividends to parent			483	928
Dividends paid to parent in excess of retained earnings			0	0
Notes payable to affiliate			(613)	(84)
Contributions from parent			0	(11)
Other			1	3
Net cash provided (used) by financing activities			(132)	834
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	$ 0	$ 0	$ 0	$ 0