Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Duke Energy Carolinas [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 199	$ 202	$ 416	$ 421
Duke Energy Carolinas [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	6	11	12
Duke Energy Carolinas [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	2	14	11	40
Related party transaction, expenses from transactions with related party	50	38	91	95
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	160	172	334	339
Progress Energy [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	9	9	17	19
Progress Energy [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	50	38	91	95
Related party transaction, expenses from transactions with related party	2	14	11	40
Duke Energy Progress [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	89	93	189	194
Duke Energy Progress [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	4	7	8
Duke Energy Progress [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	50	38	91	95
Related party transaction, expenses from transactions with related party	2	14	11	40
Duke Energy Florida [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	71	79	145	145
Duke Energy Florida [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	5	10	11
Duke Energy Ohio [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	87	103	172	188
Duke Energy Ohio [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1	2	4
Duke Energy Indiana [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	89	83	183	172
Duke Energy Indiana [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 2	$ 2	$ 4	$ 4