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Debt and Credit Facilities (Narrative) (Details)
1 Months Ended 3 Months Ended 12 Months Ended
Oct. 31, 2021
USD ($)
Jun. 30, 2020
USD ($)
Dec. 31, 2021
USD ($)
Mar. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Mar. 31, 2020
USD ($)
Debt Instrument [Line Items]            
Demand notes, maximum amount available for sale     $ 3,000,000,000      
Demand notes, maximum amount outstanding     1,500,000,000      
Principal amount of demand notes     1,066,000,000   $ 1,168,000,000  
Other loans outstanding against cash surrender value of life insurance policies     819,000,000   817,000,000  
Duke Energy Progress            
Debt Instrument [Line Items]            
Other loans outstanding against cash surrender value of life insurance policies     $ 34,000,000   $ 35,000,000  
Maximum            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Duke Energy Ohio            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Duke Energy Indiana            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Duke Energy Progress            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Progress Energy            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Duke Energy Carolinas            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Duke Energy Florida            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.65      
Maximum | Piedmont            
Debt Instrument [Line Items]            
Debt to total capitalization percentage, for each borrower     0.70      
Revolving Credit Facility            
Debt Instrument [Line Items]            
Facility size     $ 8,000,000,000 $ 8,000,000,000    
Revolving Credit Facility | Duke Energy Ohio            
Debt Instrument [Line Items]            
Facility size     775,000,000      
Revolving Credit Facility | Duke Energy Indiana            
Debt Instrument [Line Items]            
Facility size     600,000,000      
Revolving Credit Facility | Duke Energy Progress            
Debt Instrument [Line Items]            
Facility size     1,150,000,000      
Revolving Credit Facility | Duke Energy Carolinas            
Debt Instrument [Line Items]            
Facility size     1,225,000,000      
Revolving Credit Facility | Duke Energy Florida            
Debt Instrument [Line Items]            
Facility size     900,000,000      
Revolving Credit Facility | Piedmont            
Debt Instrument [Line Items]            
Facility size     700,000,000      
Revolving Credit Facility | Line of Credit | Duke Energy Ohio            
Debt Instrument [Line Items]            
Facility size $ 100,000,000          
Term of debt instrument 2 years          
Revolving Credit Facility | Line of Credit | Duke Energy Indiana            
Debt Instrument [Line Items]            
Facility size $ 300,000,000          
Term of debt instrument 2 years          
Revolving Credit Facility | Line of Credit | Duke Energy Kentucky            
Debt Instrument [Line Items]            
Facility size $ 50,000,000          
Term of debt instrument 2 years          
Revolving Credit Facility | Line of Credit | Progress Energy            
Debt Instrument [Line Items]            
Facility size     2,500,000,000      
June 2017 Three Year Revolving Credit Facility            
Debt Instrument [Line Items]            
Facility size     $ 1,000,000,000      
Term of debt instrument     3 years      
Long-term line of credit     $ 500,000,000     $ 500,000,000
Repayments of debt   $ 500,000,000