Income Taxes and Other (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Effective tax rate	29.40%	30.70%	29.60%	30.80%
Duke Energy Carolinas [Member]
Effective tax rate	34.20%	37.00%	35.80%	36.10%
Duke Energy Ohio [Member]
Effective tax rate	45.20%	47.30%	38.90%	36.90%
Duke Energy Indiana [Member]
Effective tax rate	55.10%	37.20%	47.70%	30.80%