Fair Value Measurements (Other Fair Value Disclosure) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 62,386	$ 59,863
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	69,222	69,292
Piedmont Natural Gas and Progress Energy
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized debt discount (premium), net	1,300	1,300
Duke Energy Carolinas | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	12,906	12,218
Duke Energy Carolinas | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	15,011	14,917
Progress Energy | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	19,250	19,264
Progress Energy | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	22,502	23,470
Duke Energy Progress | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	9,277	9,258
Duke Energy Progress | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	10,405	10,862
Duke Energy Florida | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	7,881	7,915
Duke Energy Florida | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	9,338	9,756
Duke Energy Ohio | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,091	3,089
Duke Energy Ohio | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,531	3,650
Duke Energy Indiana | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	4,092	4,091
Duke Energy Indiana | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	4,929	5,204
Piedmont | Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	2,967	2,780
Piedmont | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 3,337	$ 3,306