Income Taxes (Effective Tax Rates) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 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	32.50%	32.20%	33.60%	29.80%
Excise Taxes [Abstract]
Excise taxes	$ 142	$ 70	$ 291	$ 147
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	150		150
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	37.40%	37.20%	37.20%	36.70%
Excise Taxes [Abstract]
Excise taxes	37	39	78	78
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	59.90%	38.20%	36.70%	36.10%
Excise Taxes [Abstract]
Excise taxes	73	77	141	146
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	39.60%	30.30%	38.70%	31.40%
Excise Taxes [Abstract]
Excise taxes	27	26	55	52
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	38.00%	38.80%	39.80%	37.50%
Excise Taxes [Abstract]
Excise taxes	46	51	86	94
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	36.30%	39.90%	35.90%	38.10%
Excise Taxes [Abstract]
Excise taxes	24	23	55	53
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	37.50%	34.40%	37.50%	45.70%
Excise Taxes [Abstract]
Excise taxes	$ 8	$ 8	$ 17	$ 16