Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Mar. 31, 2024 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	$ 126
Due after one through five years	715
Due after five through 10 years	614
Due after 10 years	1,626
Total	3,081
Duke Energy Carolinas
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	10
Due after one through five years	245
Due after five through 10 years	359
Due after 10 years	866
Total	1,480
Progress Energy
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	101
Due after one through five years	389
Due after five through 10 years	206
Due after 10 years	658
Total	1,354
Duke Energy Progress
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	23
Due after one through five years	264
Due after five through 10 years	192
Due after 10 years	618
Total	1,097
Duke Energy Florida
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	78
Due after one through five years	125
Due after five through 10 years	14
Due after 10 years	40
Total	257
Duke Energy Indiana
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	9
Due after one through five years	18
Due after five through 10 years	11
Due after 10 years	25
Total	$ 63