Regulatory Matters (Schedule of Net Carrying Value Of Facilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) MW	Dec. 31, 2016 USD ($)
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 86,391	$ 82,520
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	27,876	26,762
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	31,887	30,181
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	12,783	11,790
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	10,286	9,924
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 19,101	$ 18,387
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,738
Net property, plant and equipment	$ 397
Generation Facilities To Be Retired [Member] | Duke Energy Carolinas [Member] | Allen Steam Station Units 1-3 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	585
Net property, plant and equipment	$ 163
Generation Facilities To Be Retired [Member] | Progress Energy [Member] | Crystal River Units 1 and 2 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Net property, plant and equipment	$ 107
Generation Facilities To Be Retired [Member] | Duke Energy Florida [Member] | Crystal River Units 1 and 2 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Net property, plant and equipment	$ 107
Generation Facilities To Be Retired [Member] | Duke Energy Indiana [Member] | Gallagher Units 2 and 4 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	280
Net property, plant and equipment	$ 127