Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Sep. 30, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	$ 137
Due after one through five years	671
Due after five through 10 years	545
Due after 10 years	1,471
Total	2,824
Duke Energy Carolinas
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	7
Due after one through five years	209
Due after five through 10 years	311
Due after 10 years	802
Total	1,329
Progress Energy
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	109
Due after one through five years	388
Due after five through 10 years	197
Due after 10 years	569
Total	1,263
Duke Energy Progress
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	21
Due after one through five years	235
Due after five through 10 years	184
Due after 10 years	531
Total	971
Duke Energy Florida
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	88
Due after one through five years	153
Due after five through 10 years	13
Due after 10 years	38
Total	292
Duke Energy Indiana
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	7
Due after one through five years	19
Due after five through 10 years	10
Due after 10 years	23
Total	$ 59