Related Party Transactions (Other Revenue and Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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	$ 851	$ 927	$ 1,112
Duke Energy Carolinas [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	21	22	21
Duke Energy Carolinas [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	133	121	18
Related party transaction, expenses from transactions with related party	198	116	91
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party		96	47
Related party transaction, expenses from transactions with related party	732	290	63
Progress Energy [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	33	34	17
Progress Energy [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	198	116	91
Related party transaction, expenses from transactions with related party	133	121	18
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	386	266	254
Duke Energy Progress [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	17	20	8
Duke Energy Progress [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	198	116	91
Related party transaction, expenses from transactions with related party	133	121	18
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	346	182	186
Duke Energy Florida [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	16	14	8
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	316	347	358
Duke Energy Ohio [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	13	15	15
Duke Energy Ohio [Member] | MarkTo Market Of Commodity Contracts And Sales Of Power [Member] | DECAM [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			24
Related party transaction, expenses from transactions with related party	24	6
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	384	422	419
Duke Energy Indiana [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 11	$ 14	$ 8