Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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	$ 753	$ 841	$ 985
Duke Energy Carolinas | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	20	20	22
Duke Energy Carolinas | Joint Dispatch Agreement (JDA) revenue | Duke Energy Progress
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	114	186	207
Related party transaction, other revenues from transactions with related party	25	60	84
Duke Energy Carolinas | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	15	15	15
Progress Energy | Corporate governance and shared service expenses | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	715	778	906
Progress Energy | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	36	37	34
Progress Energy | Joint Dispatch Agreement (JDA) revenue | Duke Energy Carolinas
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	25	60	84
Related party transaction, other revenues from transactions with related party	114	186	207
Progress Energy | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	75	76	78
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	420	462	577
Duke Energy Progress | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	17	15	13
Duke Energy Progress | Joint Dispatch Agreement (JDA) revenue | Duke Energy Carolinas
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	25	60	84
Related party transaction, other revenues from transactions with related party	114	186	207
Duke Energy Progress | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	75	76	78
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	295	316	329
Duke Energy Florida | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	19	22	21
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	326	354	374
Duke Energy Ohio | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	4	5
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	401	412	405
Duke Energy Indiana | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	8	7	7
Piedmont | Corporate governance and shared service expenses | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	140	138	170
Piedmont | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	3	3	2
Piedmont | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	90	91	93
Piedmont | Natural gas storage and transportation costs | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 23	$ 23	$ 25