Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 442	$ 358
Other	141	138
Other Noncurrent Assets
Other	8	9
Total cash, cash equivalents and restricted cash	591	505	$ 541	$ 481
Progress Energy [Member]
Current Assets
Cash and cash equivalents	67	40
Other	39	40
Other Noncurrent Assets
Other	6	7
Total cash, cash equivalents and restricted cash	112	87	110	55
Duke Energy Florida [Member]
Current Assets
Cash and cash equivalents	36	13
Other	39	40
Other Noncurrent Assets
Total cash, cash equivalents and restricted cash	$ 75	$ 53	$ 69	$ 8