Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Property, Plant and Equipment)(Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.80%	2.80%	2.90%
Duke Energy Carolinas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.70%	2.80%	2.80%
Progress Energy [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.50%	2.50%	2.60%
Duke Energy Progress [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.50%	2.50%	2.70%
Duke Energy Florida [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.70%	2.40%	2.50%
Duke Energy Ohio [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.30%	3.30%	3.20%
Duke Energy Indiana [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.00%	2.80%	3.30%