Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 259	$ 311
Other	194	222
Other Noncurrent Assets
Other	103	40
Total cash, cash equivalents and restricted cash	556	573	$ 591	$ 505
Progress Energy
Current Assets
Cash and cash equivalents	59	48
Other	39	39
Other Noncurrent Assets
Other	102	39
Total cash, cash equivalents and restricted cash	200	126	112	87
Duke Energy Florida
Current Assets
Cash and cash equivalents	11	17
Other	39	39
Other Noncurrent Assets
Total cash, cash equivalents and restricted cash	$ 50	$ 56	$ 75	$ 53