Revenue (Aging of Trade Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	$ 826	$ 969
Trade and Other Receivables, not past due	2,201	1,789
Deferred Payment Arrangements	113	215
Trade and Other Receivables	3,552	3,299
30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	194	185
60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	57	22
90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	161	119
Duke Energy Carolinas
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	308	328
Trade and Other Receivables, not past due	689	445
Deferred Payment Arrangements	66	96
Trade and Other Receivables	1,235	966
Duke Energy Carolinas | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	74	80
Duke Energy Carolinas | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	30	1
Duke Energy Carolinas | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	68	16
Progress Energy
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	242	283
Trade and Other Receivables, not past due	910	707
Deferred Payment Arrangements	29	80
Trade and Other Receivables	1,285	1,166
Progress Energy | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	63	54
Progress Energy | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	14	10
Progress Energy | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	27	32
Duke Energy Progress
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	125	167
Trade and Other Receivables, not past due	521	398
Deferred Payment Arrangements	21	52
Trade and Other Receivables	715	655
Duke Energy Progress | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	37	25
Duke Energy Progress | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	6	4
Duke Energy Progress | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	5	9
Duke Energy Florida
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	117	116
Trade and Other Receivables, not past due	388	307
Deferred Payment Arrangements	8	28
Trade and Other Receivables	569	509
Duke Energy Florida | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	26	29
Duke Energy Florida | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	8	6
Duke Energy Florida | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	22	23
Duke Energy Ohio
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	5	2
Trade and Other Receivables, not past due	65	60
Deferred Payment Arrangements	2
Trade and Other Receivables	111	102
Duke Energy Ohio | CRC
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	64	87
Duke Energy Ohio | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	7	8
Duke Energy Ohio | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	1	2
Duke Energy Ohio | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	31	30
Duke Energy Indiana
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	27	16
Trade and Other Receivables, not past due	41	26
Trade and Other Receivables	84	58
Duke Energy Indiana | CRC
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	115	134
Duke Energy Indiana | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	5	3
Duke Energy Indiana | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	1	1
Duke Energy Indiana | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	10	12
Piedmont
Financing Receivable, Past Due [Line Items]
Unbilled Receivables	7	86
Trade and Other Receivables, not past due	80	149
Deferred Payment Arrangements	6	7
Trade and Other Receivables	111	262
Piedmont | 30-60 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	6	8
Piedmont | 60-90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	3	3
Piedmont | 90 days
Financing Receivable, Past Due [Line Items]
Trade and Other Receivables	$ 9	$ 9