Related Party Transactions(OtherRevenueAndExpense)(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Duke Energy Carolinas [Member] | Corporate governance and shared service expenses [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$ 309	[1]	$ 265	[1]	$ 798	[1]	$ 769	[1]
Duke Energy Carolinas [Member] | Indemnification Coverages [Member]
Related Party Transaction, Expenses from Transactions with Related Party	5	[2]	5	[2]	16	[2]	15	[2]
Duke Energy Carolinas [Member] | Joint Dispatch Agreement Revenue [Member]
Related Party Transaction, Other Revenues from Transactions with Related Party	8	[3]	0	[3]	8	[3]	0	[3]
Duke Energy Carolinas [Member] | Joint Dispatch Agreement Expense [Member]
Related Party Transaction, Expenses from Transactions with Related Party	37	[4]	0	[4]	37	[4]	0	[4]
Duke Energy Ohio [Member] | Corporate governance and shared service expenses [Member]
Related Party Transaction, Expenses from Transactions with Related Party	103	[1]	104	[1]	279	[1]	290	[1]
Duke Energy Ohio [Member] | Indemnification Coverages [Member]
Related Party Transaction, Expenses from Transactions with Related Party	4	[2]	5	[2]	11	[2]	13	[2]
Duke Energy Indiana [Member] | Corporate governance and shared service expenses [Member]
Related Party Transaction, Expenses from Transactions with Related Party	118	[1]	100	[1]	317	[1]	306	[1]
Duke Energy Indiana [Member] | Indemnification Coverages [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$ 2	[2]	$ 1	[2]	$ 6	[2]	$ 5	[2]

[1] The Subsidiary Registrants are charged their proportionate share of corporate governance and other costs by an unconsolidated affiliate that is a consolidated affiliate of Duke Energy. Corporate governance and other shared services costs are primarily related to human resources, employee benefits, legal and accounting fees, as well as other third party costs. These amounts are recorded in Operation, maintenance and other within Operating Expenses on the Condensed Consolidated Statements of Operations and Comprehensive Income.

[2] The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other within Operating Expenses on the Condensed Consolidated Statements of Operations and Comprehensive Income.

[3] Effective with the consummation of the merger, Duke Energy Carolinas and Progress Energy Carolinas began to participate in a JDA which allowed the collective dispatch of power plants between the service territories to reduce customers' rates. The revenues from the sale of power to Progress Energy Carolinas are recorded in Regulated electric within Operating Revenue on the Condensed Consolidated Statements of Operations and Comprehensive Income.

[4] Effective with the consummation of the merger, Duke Energy Carolinas and Progress Energy Carolinas began to participate in a JDA which allowed the collective dispatch of power plants between the service territories to reduce customers' rates. The expenses from the purchase of power from Progress Energy Carolinas are recorded in Fuel used in electric generation and purchased power - regulated within Operating Expenses on the Condensed Consolidated Statements of Operations and Comprehensive Income.