Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
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	$ 841	$ 985	$ 858
Duke Energy Carolinas | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	20	22	23
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	186	207	145
Related party transaction, other revenues from transactions with related party	60	84	49
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	9
Progress Energy | Corporate governance and shared service expenses | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	778	906	736
Progress Energy | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	37	34	38
Progress Energy | Joint Dispatch Agreement (JDA) revenue | Duke Energy Carolinas
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	60	84	49
Related party transaction, other revenues from transactions with related party	186	207	145
Progress Energy | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	76	78	77
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	462	577	438
Duke Energy Progress | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	15	13	15
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	60	84	49
Related party transaction, other revenues from transactions with related party	186	207	145
Duke Energy Progress | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	76	78	77
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	316	329	298
Duke Energy Florida | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	22	21	23
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	354	374	363
Duke Energy Ohio | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	5	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	412	405	370
Duke Energy Indiana | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	7	7	8
Piedmont | Corporate governance and shared service expenses | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	138	170	50
Piedmont | Indemnification coverages | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	3	2	2
Piedmont | Intercompany natural gas transactions | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	91	93	86
Piedmont | Natural gas storage and transportation costs | Affiliated entity
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 23	$ 25	$ 25