Organization and Basis of Presentation (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Current Assets
Cash and cash equivalents	$ 548	$ 259
Other	194	194
Other Noncurrent Assets
Other	1	103
Total cash, cash equivalents and restricted cash	743	556	$ 600	$ 573
Progress Energy
Current Assets
Cash and cash equivalents	102	59
Other	17	39
Other Noncurrent Assets
Other		102
Total cash, cash equivalents and restricted cash	119	200	188	126
Duke Energy Florida
Current Assets
Cash and cash equivalents	40	11
Other	17	39
Other Noncurrent Assets
Total cash, cash equivalents and restricted cash	$ 57	$ 50	$ 35	$ 56