Regulatory Matters (Schedule of Net Carrying Value Of Facilities and Megawatt Capacity) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) MW	Dec. 31, 2017 USD ($)
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	$ 89,865	$ 86,391
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	28,550	27,876
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	33,558	31,887
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	13,561	12,783
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	$ 10,467	$ 10,286
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,631
Public utilities, property, plant and equipment, net	$ 355
Allen Steam Station Units 1-3 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	585
Public utilities, property, plant and equipment, net	$ 132
Crystal River Units 1 and 2 [Member] | Generation Facilities To Be Retired [Member] | Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	766
Public utilities, property, plant and equipment, net	$ 100
Crystal River Units 1 and 2 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	766
Public utilities, property, plant and equipment, net	$ 100
Gallagher Units 2 and 4 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	280
Public utilities, property, plant and equipment, net	$ 123