Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 1,526	$ 2,110
Short-term investments	234	190
Receivables (net of allowance for doubtful accounts)	610	784
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,233	1,157
Inventory	1,762	1,588
Other	1,122	1,051
Total current assets	6,487	6,880
Investments and Other Assets [Abstract]
Investments in equity method unconsolidated affiliates	450	460
Nuclear decommissioning trust funds	2,204	2,060
Goodwill	3,842	3,849
Intangibles, net	357	363
Notes receivable	72	62
Restricted other assets of variable interest entities	133	135
Other	1,894	2,231
Total investments and other assets	8,952	9,160
Property, Plant and Equipment
Cost	61,458	60,377
Cost, variable interest entities	1,357	913
Less: Accumulated depreciation and amortization	(19,101)	(18,709)
Generation facilities to be retired, net	73	80
Net property, plant and equipment	43,787	42,661
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	3,646	3,672
Other	159	153
Total regulatory assets and deferred debits	3,805	3,825
Total Assets	63,031	62,526
LIABILITIES AND EQUITY
Accounts payable	1,160	1,433
Notes payable and commercial paper	793	154
Non-recourse notes payable of variable interest entities	269	273
Taxes accrued	359	431
Interest accrued	254	252
Current maturities of long-term debt	1,870	1,894
Other	1,434	1,091
Total current liabilities	6,139	5,528
Long-term Debt	17,539	17,730
Non-recourse Long-term Debt of Variable Interest Entities	915	949
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	7,914	7,581
Investment tax credits	379	384
Accrued pension and other post-retirement benefit costs	829	856
Asset retirement obligations	1,999	1,936
Regulatory liabilities	2,981	2,919
Other Liabilities	1,820	1,778
Total deferred credits and other liabilities	15,922	15,454
Equity
Common Stock	1	1
Additional paid-in capital	21,140	21,132
Retained earnings	1,598	1,873
Accumulated other comprehensive loss	(320)	(234)
Net Duke Energy Corporation Shareholders' Equity	22,419	22,772
Noncontrolling interests	97	93
Total equity	22,516	22,865
Total Liabilities and Equity	63,031	62,526
Duke Energy Carolinas [Member]
ASSETS
Cash and cash equivalents	18	289
Receivables (net of allowance for doubtful accounts)	351	1,187
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	680	581
Inventory	1,024	917
Other	327	278
Total current assets	2,400	3,252
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	2,204	2,060
Other	971	968
Total investments and other assets	3,175	3,028
Property, Plant and Equipment
Cost	33,505	32,840
Less: Accumulated depreciation and amortization	(11,374)	(11,269)
Generation facilities to be retired, net	73	80
Net property, plant and equipment	22,204	21,651
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	1,891	1,894
Other	68	71
Total regulatory assets and deferred debits	1,959	1,965
Total Assets	29,738	29,896
LIABILITIES AND EQUITY
Accounts payable	448	793
Taxes accrued	109	126
Interest accrued	95	115
Current maturities of long-term debt	427	1,178
Other	481	398
Total current liabilities	1,560	2,610
Long-term Debt	7,795	7,796
Non-recourse Long-term Debt of Variable Interest Entities	300	300
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	4,891	4,555
Investment tax credits	230	233
Accrued pension and other post-retirement benefit costs	232	248
Asset retirement obligations	1,904	1,846
Regulatory liabilities	1,993	1,928
Other Liabilities	900	926
Total deferred credits and other liabilities	10,150	9,736
Equity
Member's Equity	9,950	9,473
Accumulated other comprehensive loss	(17)	(19)
Total member's equity	9,933	9,454
Total Liabilities and Member's Equity	29,738	29,896
Duke Energy Ohio [Member]
ASSETS
Cash and cash equivalents	22	99
Receivables (net of allowance for doubtful accounts)	760	681
Inventory	262	243
Other	258	220
Total current assets	1,302	1,243
Investments and Other Assets [Abstract]
Goodwill	921	921
Intangibles, net	136	143
Other	63	58
Total investments and other assets	1,120	1,122
Property, Plant and Equipment
Cost	10,612	10,632
Less: Accumulated depreciation and amortization	(2,600)	(2,594)
Net property, plant and equipment	8,012	8,038
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	529	520
Other	15	16
Total regulatory assets and deferred debits	544	536
Total Assets	10,978	10,939
LIABILITIES AND EQUITY
Accounts payable	363	402
Taxes accrued	158	180
Interest accrued	23	23
Current maturities of long-term debt	757	507
Other	117	122
Total current liabilities	1,418	1,234
Long-term Debt	1,794	2,048
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	1,882	1,853
Investment tax credits	7	8
Accrued pension and other post-retirement benefit costs	142	147
Asset retirement obligations	28	27
Regulatory liabilities	261	273
Other Liabilities	187	182
Total deferred credits and other liabilities	2,507	2,490
Equity
Common Stock	762	762
Additional paid-in capital	5,057	5,085
Retained earnings	(533)	(652)
Accumulated other comprehensive loss	(27)	(28)
Net Duke Energy Corporation Shareholders' Equity	5,259	5,167
Total equity	5,259	5,167
Total Liabilities and Equity	10,978	10,939
Duke Energy Indiana [Member]
ASSETS
Cash and cash equivalents	19	16
Receivables (net of allowance for doubtful accounts)	190	198
Inventory	358	330
Other	107	135
Total current assets	674	679
Investments and Other Assets [Abstract]
Intangibles, net	44	50
Other	111	113
Total investments and other assets	155	163
Property, Plant and Equipment
Cost	11,880	11,791
Less: Accumulated depreciation and amortization	(3,575)	(3,393)
Net property, plant and equipment	8,305	8,398
Total Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	781	798
Other	24	24
Total regulatory assets and deferred debits	805	822
Total Assets	9,939	10,062
LIABILITIES AND EQUITY
Accounts payable	209	273
Notes payable and commercial paper	113	300
Taxes accrued	50	74
Interest accrued	55	50
Current maturities of long-term debt	5	6
Other	132	93
Total current liabilities	564	796
Long-term Debt	3,702	3,453
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes	835	927
Investment tax credits	142	143
Accrued pension and other post-retirement benefit costs	154	161
Asset retirement obligations	44	43
Regulatory liabilities	695	683
Other Liabilities	134	122
Total deferred credits and other liabilities	2,004	2,079
Equity
Common Stock	1	1
Additional paid-in capital	1,384	1,358
Retained earnings	2,278	2,368
Accumulated other comprehensive loss	6	7
Net Duke Energy Corporation Shareholders' Equity	3,669	3,734
Total equity	3,669	3,734
Total Liabilities and Equity	$ 9,939	$ 10,062