Income Taxes (Effective Tax Rates) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
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	7.80%	12.40%	(6.40%)	12.50%
Duke Energy Carolinas
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	12.00%	16.70%	13.60%	17.70%
Progress Energy
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	10.40%	15.30%	13.40%	16.20%
Duke Energy Progress
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	3.10%	14.70%	10.00%	16.10%
Duke Energy Florida
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	21.40%	16.50%	20.30%	18.00%
Duke Energy Ohio
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	16.70%	12.90%	16.60%	15.20%
Duke Energy Indiana
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	19.60%	23.20%	19.40%	23.70%
Piedmont Natural Gas
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	16.70%	35.70%	3.70%	18.50%