Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 1,761	$ 2,110
Short-term investments	335	190
Receivables (net of allowance for doubtful accounts)	1,596	784
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,250	1,157
Inventory	3,041	1,588
Other	2,123	1,051
Total current assets	10,106	6,880
Investments and Other Assets [Abstract]
Investments in equity method unconsolidated affiliates	542	460
Nuclear decommissioning trust funds	4,155	2,060
Goodwill	16,180	3,849
Intangibles, net	359	363
Notes receivable	74	62
Restricted other assets of variable interest entities	115	135
Other	2,186	2,231
Total investments and other assets	23,611	9,160
Property, Plant and Equipment
Cost	100,156	60,377
Cost, variable interest entities	961	913
Less: Accumulated depreciation and amortization	(32,318)	(18,709)
Generation facilities to be retired, net	232	80
Net property, plant and equipment	69,031	42,661
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	9,097	3,672
Other	163	153
Total regulatory assets and deferred debits	9,260	3,825
Total Assets	112,008	62,526
LIABILITIES AND EQUITY
Accounts payable	1,912	1,433
Notes payable and commercial paper	600	154
Non-recourse notes payable of variable interest entities	275	273
Taxes accrued	601	431
Interest accrued	474	252
Current maturities of long-term debt	2,488	1,894
Other	2,206	1,091
Total current liabilities	8,556	5,528
Long-term Debt	35,198	17,730
Non-recourse Long-term Debt of Variable Interest Entities	911	949
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	10,317	7,581
Investment tax credits	462	384
Accrued pension and other post-retirement benefit costs	2,542	856
Asset retirement obligations	4,846	1,936
Regulatory liabilities	5,739	2,919
Other Liabilities	2,349	1,778
Total deferred credits and other liabilities	26,255	15,454
Commitments and Contingencies	0	0
Preferred stock of subsidiaries	93	0
Equity
Common Stock	1	1
Additional paid-in capital	39,249	21,132
Retained earnings	1,995	1,873
Accumulated other comprehensive loss	(340)	(234)
Net Duke Energy Corporation Shareholders' Equity	40,905	22,772
Noncontrolling interests	90	93
Total equity	40,995	22,865
Total Liabilities and Equity	112,008	62,526
Duke Energy Carolinas [Member]
ASSETS
Cash and cash equivalents	314	289
Receivables (net of allowance for doubtful accounts)	135	262
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	738	581
Due from Related Parties, Current	2	2
Notes Receivable, Related Parties, Current	811	923
Inventory	993	917
Other	445	278
Total current assets	3,438	3,252
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	2,311	2,060
Other	804	968
Total investments and other assets	3,115	3,028
Property, Plant and Equipment
Cost	33,961	32,840
Less: Accumulated depreciation and amortization	(11,553)	(11,269)
Generation facilities to be retired, net	68	80
Net property, plant and equipment	22,476	21,651
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	1,814	1,894
Other	72	71
Total regulatory assets and deferred debits	1,886	1,965
Total Assets	30,915	29,896
LIABILITIES AND EQUITY
Accounts payable	426	637
Due to Related Parties, Current	148	156
Taxes accrued	142	126
Interest accrued	145	115
Current maturities of long-term debt	427	1,178
Other	519	398
Total current liabilities	1,807	2,610
Long-term Debt	8,139	7,496
Non-recourse Long-term Debt of Variable Interest Entities	300	300
Long-term debt payable to affiliated companies	300	300
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	5,063	4,555
Investment tax credits	216	233
Accrued pension and other post-retirement benefit costs	226	248
Asset retirement obligations	1,934	1,846
Regulatory liabilities	2,034	1,928
Other Liabilities	955	926
Total deferred credits and other liabilities	10,428	9,736
Commitments and Contingencies	0	0
Equity
Member's Equity	9,958	9,473
Accumulated other comprehensive loss	(17)	(19)
Total member's equity	9,941	9,454
Total Liabilities and Member's Equity	30,915	29,896
Duke Energy Ohio [Member]
ASSETS
Cash and cash equivalents	13	99
Receivables (net of allowance for doubtful accounts)	96	137
Due from Related Parties, Current	92	143
Notes Receivable, Related Parties, Current	84	401
Inventory	221	243
Other	259	220
Total current assets	765	1,243
Investments and Other Assets [Abstract]
Goodwill	921	921
Intangibles, net	132	143
Other	62	58
Total investments and other assets	1,115	1,122
Property, Plant and Equipment
Cost	10,708	10,632
Less: Accumulated depreciation and amortization	(2,646)	(2,594)
Net property, plant and equipment	8,062	8,038
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	538	520
Other	14	16
Total regulatory assets and deferred debits	552	536
Total Assets	10,494	10,939
LIABILITIES AND EQUITY
Accounts payable	248	318
Due to Related Parties, Current	68	84
Notes Payable, Related Parties, Current	86	0
Taxes accrued	131	180
Interest accrued	30	23
Current maturities of long-term debt	261	507
Other	105	122
Total current liabilities	929	1,234
Long-term Debt	1,785	2,048
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	1,882	1,853
Investment tax credits	6	8
Accrued pension and other post-retirement benefit costs	140	147
Asset retirement obligations	28	27
Regulatory liabilities	264	273
Other Liabilities	187	182
Total deferred credits and other liabilities	2,507	2,490
Commitments and Contingencies	0	0
Equity
Common Stock	762	762
Additional paid-in capital	5,057	5,085
Retained earnings	519	652
Accumulated other comprehensive loss	(27)	(28)
Net Duke Energy Corporation Shareholders' Equity	5,273	5,167
Total equity	5,273	5,167
Total Liabilities and Equity	10,494	10,939
Duke Energy Indiana [Member]
ASSETS
Cash and cash equivalents	18	16
Receivables (net of allowance for doubtful accounts)	23	42
Due from Related Parties, Current	133	156
Inventory	356	330
Other	124	135
Total current assets	654	679
Investments and Other Assets [Abstract]
Intangibles, net	43	50
Other	110	113
Total investments and other assets	153	163
Property, Plant and Equipment
Cost	11,843	11,791
Less: Accumulated depreciation and amortization	(3,638)	(3,393)
Net property, plant and equipment	8,205	8,398
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	784	798
Other	23	24
Total regulatory assets and deferred debits	807	822
Total Assets	9,819	10,062
LIABILITIES AND EQUITY
Accounts payable	147	201
Due to Related Parties, Current	52	72
Notes Payable, Related Parties, Current	55	300
Taxes accrued	58	74
Interest accrued	49	50
Current maturities of long-term debt	404	6
Other	170	93
Total current liabilities	935	796
Long-term Debt	3,150	3,303
Long-term debt payable to affiliated companies	150	150
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	826	927
Investment tax credits	142	143
Accrued pension and other post-retirement benefit costs	152	161
Asset retirement obligations	44	43
Regulatory liabilities	706	683
Other Liabilities	64	122
Total deferred credits and other liabilities	1,934	2,079
Commitments and Contingencies	0	0
Equity
Common Stock	1	1
Additional paid-in capital	1,384	1,358
Retained earnings	2,259	2,368
Accumulated other comprehensive loss	6	7
Net Duke Energy Corporation Shareholders' Equity	3,650	3,734
Total equity	3,650	3,734
Total Liabilities and Equity	$ 9,819	$ 10,062