Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 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	$ 204	$ 211	$ 620	$ 632
Duke Energy Carolinas [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	6	16	18
Duke Energy Carolinas [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	10	7	21	47
Related party transaction, expenses from transactions with related party	36	48	127	143
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	182	184	515	523
Progress Energy [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	9	10	25	29
Progress Energy [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	36	48	127	143
Related party transaction, expenses from transactions with related party	10	7	21	47
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	103	101	292	296
Duke Energy Progress [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	4	10	12
Duke Energy Progress [Member] | Joint Dispatch Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	36	48	127	143
Related party transaction, expenses from transactions with related party	10	7	21	47
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	79	83	223	227
Duke Energy Florida [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	5	6	15	17
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	89	88	261	276
Duke Energy Ohio [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1	4	5
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	96	87	279	259
Duke Energy Indiana [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 2	$ 2	$ 6	$ 6