Schedule I - Condensed Parent Company Financial Statements (Condensed Statements Of Operations) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions
Operating revenues	$ 5,695	$ 6,722	$ 3,577	$ 3,630	$ 3,368	$ 3,964	$ 3,534	$ 3,663	$ 19,624	$ 14,529	$ 14,272
Operating expenses									16,514	11,760	11,964
Operating income (loss)	767	1,078	786	495	517	767	679	814	3,126	2,777	2,461
Equity in earnings of unconsolidated affiliates									148	160	116
Other income and expenses, net									397	376	370
Interest Expense									1,242	859	840
Income Loss From Continuing Operations Before Income Taxes									2,451	2,465	2,210
Income Tax Expense or Benefit from Continuing Operations									705	752	890
Income From Continuing Operations	406	594	449	297	290	469	441	513	1,746	1,713	1,320
Income (Loss) From Discontinued Operations, net of tax									36	1	3
Net income	437	598	448	299	290	470	441	513	1,782	1,714	1,323
Comprehensive income attributable to Duke Energy Corporation									1,696	1,470	1,694
EPS, basic	$ 0.57	$ 0.84	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.01	$ 3.83	$ 2.99
EPS, diluted	$ 0.57	$ 0.84	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.01	$ 3.83	$ 2.99
Basic									$ 0.06	$ 0	$ 0.01
Diluted									$ 0.06	$ 0	$ 0.01
Basic	$ 0.62	$ 0.85	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.07	$ 3.83	$ 3.00
Diluted	$ 0.62	$ 0.85	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.07	$ 3.83	$ 3.00
Dividends declared per share									$ 3.03	$ 2.97	$ 2.91
Average shares, basic									574	444	439
Average shares, diluted									575	444	440
Parent Company [Member]
Condensed Financial Statements, Captions
Operating revenues									0	0	0
Operating expenses									23	6	52
Operating income (loss)									(23)	(6)	(52)
Equity in earnings of unconsolidated affiliates									1,837	1,782	1,384
Other income and expenses, net									19	21	6
Interest Expense									197	156	139
Income Loss From Continuing Operations Before Income Taxes									1,636	1,641	1,199
Income Tax Expense or Benefit from Continuing Operations									(96)	(64)	(118)
Income From Continuing Operations									1,732	1,705	1,317
Income (Loss) From Discontinued Operations, net of tax									36	1	3
Net income									1,768	1,706	1,320
Comprehensive income attributable to Duke Energy Corporation									$ 1,696	$ 1,470	$ 1,694
EPS, basic									$ 3.01	$ 3.83	$ 2.99
EPS, diluted									$ 3.01	$ 3.83	$ 2.99
Basic									$ 0.06	$ 0.00	$ 0.01
Diluted									$ 0.06	$ 0.00	$ 0.01
Basic									$ 3.07	$ 3.83	$ 3.00
Diluted									$ 3.07	$ 3.83	$ 3.00
Dividends declared per share									$ 3.03	$ 2.97	$ 2.91
Average shares, basic									574	444	439
Average shares, diluted									575	444	440