Summary of Significant Accounting Policies (Property, Plant and Equipment) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.00%	3.10%	3.00%
Duke Energy Carolinas
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.80%	2.80%	2.80%
Progress Energy
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.20%	3.10%	2.90%
Duke Energy Progress
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.10%	3.10%	2.90%
Duke Energy Florida
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.30%	3.10%	3.00%
Duke Energy Ohio
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.90%	2.60%	2.80%
Duke Energy Indiana
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.50%	3.30%	3.30%
Piedmont
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.30%	2.40%	2.50%