Revenue (Aging of Trade Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	$ 788	$ 843
Trade and Other Receivables, not past due	1,800
Trade and Other Receivables	3,172
30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	227
60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	94
90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	263
Duke Energy Carolinas
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	284	298
Trade and Other Receivables, not past due	475
Trade and Other Receivables	969
Duke Energy Carolinas | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	86
Duke Energy Carolinas | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	39
Duke Energy Carolinas | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	85
Progress Energy
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	274	217
Trade and Other Receivables, not past due	847
Trade and Other Receivables	1,304
Progress Energy | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	84
Progress Energy | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	31
Progress Energy | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	68
Duke Energy Progress
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	139	122
Trade and Other Receivables, not past due	439
Trade and Other Receivables	683
Duke Energy Progress | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	48
Duke Energy Progress | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	20
Duke Energy Progress | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	37
Duke Energy Florida
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	135	95
Trade and Other Receivables, not past due	406
Trade and Other Receivables	619
Duke Energy Florida | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	36
Duke Energy Florida | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	11
Duke Energy Florida | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	31
Duke Energy Ohio
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	1	1
Trade and Other Receivables, not past due	44
Trade and Other Receivables	95
Duke Energy Ohio | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	7
Duke Energy Ohio | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	3
Duke Energy Ohio | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	40
Duke Energy Indiana
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	16	16
Trade and Other Receivables, not past due	23
Trade and Other Receivables	51
Duke Energy Indiana | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	2
Duke Energy Indiana | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	1
Duke Energy Indiana | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	9
Piedmont Natural Gas
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	5	$ 78
Trade and Other Receivables, not past due	66
Trade and Other Receivables	102
Piedmont Natural Gas | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	8
Piedmont Natural Gas | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	3
Piedmont Natural Gas | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	$ 20