Income Taxes (Effective Tax Rates) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	31.50%	29.40%	32.60%	29.60%
Excise Taxes [Abstract]
Excise taxes	$ 170	$ 178	$ 461	$ 325
State [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Net reduction in deferred tax liability	145		145
State [Member] | Current [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Statutory tax rate			6.90%
State [Member] | January 2014 [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Statutory tax rate			6.00%
State [Member] | January 2015 [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Statutory tax rate			5.00%
Duke Energy Carolinas [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	37.90%	34.20%	37.50%	35.80%
Excise Taxes [Abstract]
Excise taxes	46	47	124	125
Progress Energy [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	38.80%	32.80%	38.10%	34.70%
Excise Taxes [Abstract]
Excise taxes	89	95	230	241
Duke Energy Progress [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	35.70%	31.90%	37.30%	31.60%
Excise Taxes [Abstract]
Excise taxes	33	33	88	85
Duke Energy Florida [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	40.00%	35.90%	40.00%	36.90%
Excise Taxes [Abstract]
Excise taxes	56	62	142	156
Duke Energy Ohio [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	42.90%	45.20%	40.40%	38.90%
Excise Taxes [Abstract]
Excise taxes	26	26	81	79
Duke Energy Indiana [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	36.60%	55.10%	37.20%	47.70%
Excise Taxes [Abstract]
Excise taxes	$ 9	$ 9	$ 26	$ 25