Debt and Credit Facilities (Short Term Obligations Classified As Long Term) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	$ 937	$ 937
Tax Exempt Bonds
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	312	312
Commercial Paper
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	625	625
Duke Energy Carolinas
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	300	300
Duke Energy Carolinas | Commercial Paper
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	300	300
Duke Energy Progress
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150	150
Duke Energy Progress | Commercial Paper
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150	150
Duke Energy Ohio
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	52	52
Duke Energy Ohio | Tax Exempt Bonds
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	27	27
Duke Energy Ohio | Commercial Paper
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	25	25
Duke Energy Indiana
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	435	435
Duke Energy Indiana | Tax Exempt Bonds
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	285	285
Duke Energy Indiana | Commercial Paper
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	$ 150	$ 150