XML 105 R63.htm IDEA: XBRL DOCUMENT v3.8.0.1
Debt and Credit Facilities (Narrative) (Details) - USD ($)
9 Months Ended
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Feb. 28, 2017
Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size $ 8,000,000,000   $ 8,000,000,000 $ 7,500,000,000.0
Parent Company [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size 2,850,000,000      
Parent Company [Member] | June 2017 Three Year Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size   $ 1,000,000,000.0    
Long-term Line of Credit $ 270,000,000      
Debt Instrument, Term 3 years      
Piedmont Natural Gas [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size $ 500,000,000     $ 850,000,000
Piedmont Natural Gas [Member] | June 2017 Piedmont Term Loan Facility [Member]        
Debt Instrument [Line Items]        
Facility size   $ 250,000,000    
Long-term Line of Credit $ 250,000,000      
Debt Instrument, Term 18 months      
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size $ 1,350,000,000      
Duke Energy Carolinas [Member] | USDOJ [Member] | North Carolina Ash Basins [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Minimum Master Credit Facility Balance Required 250,000,000      
Duke Energy Progress [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Facility size 1,250,000,000      
Duke Energy Progress [Member] | USDOJ [Member] | North Carolina Ash Basins [Member] | Revolving Credit Facility [Member]        
Debt Instrument [Line Items]        
Minimum Master Credit Facility Balance Required $ 250,000,000