Fair Value Measurements (Additional Fair Value Disclosure) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 47,895	$ 38,868
Long-term debt, fair value	49,161	41,767
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	9,603	8,367
Long-term debt, fair value	10,494	9,156
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	17,541	14,464
Long-term debt, fair value	19,107	15,856
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	7,011	6,518
Long-term debt, fair value	7,357	6,757
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	6,125	4,266
Long-term debt, fair value	6,728	4,908
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,884	1,598
Long-term debt, fair value	2,020	1,724
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,786	3,768
Long-term debt, fair value	$ 4,260	$ 4,219