Regulatory Matters (Schedule of Net Carrying Value Of Facilities and Megawatt Capacity) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) MW	Dec. 31, 2034 asset	Dec. 31, 2020 USD ($) MW
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	$ 110,236		$ 106,782
Duke Energy Carolinas
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	33,920		33,187
Duke Energy Progress
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	23,328		22,987
Duke Energy Florida
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	17,461		16,563
Duke Energy Indiana
Public Utilities, General Disclosures [Line Items]
Public utilities, property, plant and equipment, net	$ 11,770		$ 11,721
Generation facilities to be retired
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	8,707
Public utilities, property, plant and equipment, net	$ 6,038
Generation facilities to be retired | Duke Energy Carolinas | Allen Steam Station Units 1-2
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	324
Public utilities, property, plant and equipment, net	$ 19
Generation facilities to be retired | Duke Energy Carolinas | Allen Steam Station Units 4-5
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	516
Public utilities, property, plant and equipment, net	$ 362
Generation facilities to be retired | Duke Energy Carolinas | Cliffside Unit 5
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	544
Public utilities, property, plant and equipment, net	$ 367
Generation facilities to be retired | Duke Energy Carolinas | Allen Steam Station 3
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW			270
Public utilities, property, plant and equipment, net			$ 26
Generation facilities to be retired | Duke Energy Progress | Mayo Unit 1
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	704
Public utilities, property, plant and equipment, net	$ 640
Generation facilities to be retired | Duke Energy Progress | Roxboro Units 3-4
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,392
Public utilities, property, plant and equipment, net	$ 465
Generation facilities to be retired | Duke Energy Florida | Crystal River Units 4-5
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,410
Public utilities, property, plant and equipment, net	$ 1,658
Generation facilities to be retired | Duke Energy Florida | Crystal River Units 4 and 5 | Forecast
Public Utilities, General Disclosures [Line Items]
Facilities retiring ahead of schedule | asset		2
Facilities retiring ahead of schedule, years ahead		8 years
Generation facilities to be retired | Duke Energy Indiana | Gibson Units 1-5
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	2,822
Public utilities, property, plant and equipment, net	$ 1,814
Generation facilities to be retired | Duke Energy Indiana | Cayuga Units 1-2
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	995
Public utilities, property, plant and equipment, net	$ 713
Generation facilities to be retired | Duke Energy Indiana | Gallagher Units 2 and 4
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW			280
Public utilities, property, plant and equipment, net			$ 102