Derivatives and Hedging (Location and Fair Value Amounts of Derivatives Reflected in the Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	$ 543	$ 61
Location and fair value amounts of derivatives (Liability)	415	324
Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	363	48
Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	180	13
Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	134	64
Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	281	260
Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	536	43
Location and fair value amounts of derivatives (Liability)	318	251
Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	18
Location and fair value amounts of derivatives (Liability)	97	73
Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	359	30
Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	177	13
Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	33	30
Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	128	137
Not Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	18
Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	19	5
Not Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	5
Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	37	14
Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	120	70
Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3
Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	45	15
Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	29	48
Duke Energy Carolinas
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	271	20
Location and fair value amounts of derivatives (Liability)	18	20
Duke Energy Carolinas | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	171	14
Duke Energy Carolinas | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	100	6
Duke Energy Carolinas | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	18	17
Duke Energy Carolinas | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		3
Duke Energy Carolinas | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	271	20
Location and fair value amounts of derivatives (Liability)	12	16
Duke Energy Carolinas | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	4
Duke Energy Carolinas | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	171	14
Duke Energy Carolinas | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	100	6
Duke Energy Carolinas | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12	13
Duke Energy Carolinas | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		3
Duke Energy Carolinas | Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	4
Progress Energy
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	215	33
Location and fair value amounts of derivatives (Liability)	12	29
Progress Energy | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	137	27
Progress Energy | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	78	6
Progress Energy | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12	2
Progress Energy | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		27
Progress Energy | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	213	15
Location and fair value amounts of derivatives (Liability)		29
Progress Energy | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	18
Location and fair value amounts of derivatives (Liability)	12
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	135	9
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	78	6
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		27
Progress Energy | Not Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	18
Progress Energy | Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12
Duke Energy Progress
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	215	33
Location and fair value amounts of derivatives (Liability)		14
Duke Energy Progress | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	137	27
Duke Energy Progress | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	78	6
Duke Energy Progress | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Duke Energy Progress | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		12
Duke Energy Progress | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	213	15
Location and fair value amounts of derivatives (Liability)		14
Duke Energy Progress | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	18
Duke Energy Progress | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	135	9
Duke Energy Progress | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	78	6
Duke Energy Progress | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Duke Energy Progress | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		12
Duke Energy Progress | Not Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	18
Duke Energy Florida
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12
Duke Energy Florida | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12
Duke Energy Florida | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12
Duke Energy Florida | Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12
Duke Energy Ohio
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	1
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Ohio | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	1
Duke Energy Ohio | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	1
Duke Energy Ohio | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	5
Duke Energy Ohio | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	1
Duke Energy Ohio | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Ohio | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	1
Duke Energy Ohio | Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	1
Duke Energy Ohio | Not Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	5
Duke Energy Indiana
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	36	6
Location and fair value amounts of derivatives (Liability)	2	1
Duke Energy Indiana | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	36	6
Duke Energy Indiana | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	2	1
Duke Energy Indiana | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	36	6
Location and fair value amounts of derivatives (Liability)	2	1
Duke Energy Indiana | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	36	6
Duke Energy Indiana | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	2	1
Piedmont
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12	1
Location and fair value amounts of derivatives (Liability)	148	122
Piedmont | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12	1
Piedmont | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	20	15
Piedmont | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	128	107
Piedmont | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12	1
Location and fair value amounts of derivatives (Liability)	148	122
Piedmont | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12	1
Piedmont | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	20	15
Piedmont | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	$ 128	$ 107