Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 98	$ 156
Duke Energy Carolinas [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	23	11
Progress Energy [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	59	54
Duke Energy Progress [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	14	6
Duke Energy Florida [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	28	31
Duke Energy Ohio [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 4	$ 80