Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 4,873	$ 4,238
Other debt securities
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 520
Duke Energy (Parent) | Debt Maturing October 2021, 5.125% interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	5.125%
Current maturities of long-term debt	$ 500
Duke Energy (Parent) | Debt Maturing March 2022, 3.227% interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	3.227%
Current maturities of long-term debt	$ 300
Duke Energy (Parent) | Debt Maturing March 2022, 0.775%, floating interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	0.764%
Current maturities of long-term debt	$ 300
Duke Energy (Parent) | Debt Maturing August 2022, 3.050% interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	3.05%
Current maturities of long-term debt	$ 500
Duke Energy (Parent) | Debt Maturing August 2022, 2.400% interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	2.40%
Current maturities of long-term debt	$ 500
Duke Energy Florida
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 276	823
Duke Energy Florida | Debt Maturing November 2021, 0.391%, floating interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	0.372%
Current maturities of long-term debt	$ 200
Duke Energy Progress
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,207	603
Duke Energy Progress | Debt Maturing February 2022, 0.305%, floating interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	0.305%
Current maturities of long-term debt	$ 700
Duke Energy Progress | Debt Maturing May 2022, 2.800%, interest rate | First Mortgage Bonds
Debt Instrument [Line Items]
Interest Rate	2.80%
Current maturities of long-term debt	$ 500
Progress Energy
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,932	1,426
Progress Energy | Debt Maturing April 2022, 3.150% interest rate | Unsecured Debt
Debt Instrument [Line Items]
Interest Rate	3.15%
Current maturities of long-term debt	$ 450
Duke Energy Indiana
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 151	70
Duke Energy Indiana | Debt Maturing January 2022, 8.850% interest rate | First Mortgage Bonds
Debt Instrument [Line Items]
Interest Rate	8.85%
Current maturities of long-term debt	$ 53
Duke Energy Carolinas
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 357	$ 506
Duke Energy Carolinas | Debt Maturing May 2022, 3.350% interest rate | First Mortgage Bonds
Debt Instrument [Line Items]
Interest Rate	3.35%
Current maturities of long-term debt	$ 350