Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Duke Energy Carolinas | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 198	$ 197	$ 528	$ 606
Duke Energy Carolinas | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	5	15	15
Duke Energy Carolinas | JDA | Duke Energy Progress
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	28	32	72	145
Related party transaction, other revenues from transactions with related party	6	12	16	52
Duke Energy Carolinas | Intercompany natural gas purchases and sales | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	10	0	26	7
Progress Energy | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	185	194	520	553
Progress Energy | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	9	8	27	27
Progress Energy | JDA | Duke Energy Carolinas
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	12	16	52
Related party transaction, other revenues from transactions with related party	28	32	72	145
Progress Energy | Intercompany natural gas purchases and sales | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	18	19	56	57
Duke Energy Progress | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	113	114	301	328
Duke Energy Progress | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	3	13	11
Duke Energy Progress | JDA | Duke Energy Carolinas
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	12	16	52
Related party transaction, other revenues from transactions with related party	28	32	72	145
Duke Energy Progress | Intercompany natural gas purchases and sales | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	18	19	56	57
Duke Energy Florida | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	72	80	219	225
Duke Energy Florida | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	5	14	16
Duke Energy Ohio | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	80	90	241	258
Duke Energy Ohio | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1	3	3
Duke Energy Indiana | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	102	109	300	299
Duke Energy Indiana | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	2	2	6	5
Piedmont Natural Gas | Corporate governance and shared service expenses | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	31	33	102	102
Piedmont Natural Gas | Indemnification coverages | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1	2	2
Piedmont Natural Gas | Intercompany natural gas purchases and sales | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	28	19	82	64
Piedmont Natural Gas | Natural gas storage and transportation costs | Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 6	$ 6	$ 17	$ 17