Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Jun. 30, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	$ 137
Due after one through five years	930
Due after five through 10 years	484
Due after 10 years	1,417
Total	2,968
Duke Energy Carolinas
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	7
Due after one through five years	350
Due after five through 10 years	209
Due after 10 years	777
Total	1,343
Progress Energy
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	118
Due after one through five years	501
Due after five through 10 years	204
Due after 10 years	553
Total	1,376
Duke Energy Progress
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	24
Due after one through five years	266
Due after five through 10 years	189
Due after 10 years	515
Total	994
Duke Energy Florida
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	94
Due after one through five years	235
Due after five through 10 years	15
Due after 10 years	38
Total	382
Duke Energy Indiana
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	9
Due after one through five years	23
Due after five through 10 years	6
Due after 10 years	23
Total	$ 61