Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 343	$ 259
Other	170	194
Other Noncurrent Assets
Other	7	103
Total cash, cash equivalents and restricted cash	520	556	$ 573	$ 591
Duke Energy Carolinas
Current Assets
Cash and cash equivalents	7	21
Other Noncurrent Assets
Other	1
Total cash, cash equivalents and restricted cash	8	21	18	33
Progress Energy
Current Assets
Cash and cash equivalents	70	59
Other	39	39
Other Noncurrent Assets
Other	4	102
Total cash, cash equivalents and restricted cash	113	200	126	112
Duke Energy Progress
Current Assets
Cash and cash equivalents	35	39
Other Noncurrent Assets
Other	4
Total cash, cash equivalents and restricted cash	39	39	22	23
Duke Energy Florida
Current Assets
Cash and cash equivalents	23	11
Other	39	39
Other Noncurrent Assets
Total cash, cash equivalents and restricted cash	$ 62	$ 50	$ 56	$ 75