Derivatives and Hedging (Location and Fair Value Amounts of Derivatives Reflected in the Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	$ 86	$ 25
Location and fair value amounts of derivatives (Liability)	359	300
Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	60	24
Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	26	1
Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	84	118
Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	275	182
Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	83	18
Location and fair value amounts of derivatives (Liability)	257	223
Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	6
Location and fair value amounts of derivatives (Liability)	102	53
Equity Securities Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)		24
Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	57	17
Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	26	1
Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	26	67
Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	129	156
Not Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	6
Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	27	8
Not Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	5
Not Designated as Hedging Instruments | Equity Securities Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Not Designated as Hedging Instruments | Equity Securities Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		24
Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17
Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	85
Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	14	19
Designated as Hedging Instruments | Interest Rate Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	56	21
Duke Energy Carolinas
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	38
Location and fair value amounts of derivatives (Liability)	33	49
Duke Energy Carolinas | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	24
Duke Energy Carolinas | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	14
Duke Energy Carolinas | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	29	39
Duke Energy Carolinas | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	10
Duke Energy Carolinas | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	38
Location and fair value amounts of derivatives (Liability)	16	43
Duke Energy Carolinas | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	6
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)	24
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)	14
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	33
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)	4	10
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)	17	6
Progress Energy
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	33	7
Location and fair value amounts of derivatives (Liability)	36	88
Progress Energy | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	21	7
Progress Energy | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12
Progress Energy | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	51
Progress Energy | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	27	37
Progress Energy | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	30
Location and fair value amounts of derivatives (Liability)	27	63
Progress Energy | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	6
Location and fair value amounts of derivatives (Liability)	9	1
Progress Energy | Equity Securities Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)		24
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	18
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12
Progress Energy | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		26
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	37
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)	3	6
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)	9	1
Progress Energy | Not Designated as Hedging Instruments | Equity Securities Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Progress Energy | Not Designated as Hedging Instruments | Equity Securities Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		24
Duke Energy Progress
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	33
Location and fair value amounts of derivatives (Liability)	20	49
Duke Energy Progress | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	21
Duke Energy Progress | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12
Duke Energy Progress | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	27
Duke Energy Progress | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	11	22
Duke Energy Progress | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	30
Location and fair value amounts of derivatives (Liability)	11	48
Duke Energy Progress | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3
Location and fair value amounts of derivatives (Liability)	9	1
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)	18
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)	12
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)		26
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)	11	22
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)	3
Duke Energy Progress | Not Designated as Hedging Instruments | Interest Rate Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	1
Duke Energy Florida
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		7
Location and fair value amounts of derivatives (Liability)		24
Duke Energy Florida | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		7
Duke Energy Florida | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		24
Duke Energy Florida | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		6
Duke Energy Florida | Equity Securities Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)		24
Duke Energy Florida | Not Designated as Hedging Instruments | Interest Rate Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		6
Duke Energy Florida | Not Designated as Hedging Instruments | Equity Securities Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Florida | Not Designated as Hedging Instruments | Equity Securities Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		24
Duke Energy Ohio
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	4
Location and fair value amounts of derivatives (Liability)	7	6
Duke Energy Ohio | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Duke Energy Ohio | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Ohio | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	2	1
Duke Energy Ohio | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	5
Duke Energy Ohio | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	4
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Ohio | Interest Rate Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	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)	2	3
Duke Energy Ohio | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Ohio | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	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)	5	5
Duke Energy Indiana
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	8	13
Location and fair value amounts of derivatives (Liability)		1
Duke Energy Indiana | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	8	13
Duke Energy Indiana | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		1
Duke Energy Indiana | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	8	13
Location and fair value amounts of derivatives (Liability)		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)	8	13
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)		1
Piedmont Natural Gas
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Location and fair value amounts of derivatives (Liability)	111	117
Piedmont Natural Gas | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Piedmont Natural Gas | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	13	7
Piedmont Natural Gas | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	98	110
Piedmont Natural Gas | Commodity Contracts
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Location and fair value amounts of derivatives (Liability)	111	117
Piedmont Natural Gas | Not Designated as Hedging Instruments | Commodity Contracts | Current assets
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Piedmont Natural Gas | Not Designated as Hedging Instruments | Commodity Contracts | Current liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	13	7
Piedmont Natural Gas | Not Designated as Hedging Instruments | Commodity Contracts | Noncurrent liabilities
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	$ 98	$ 110