Condensed Consolidated Statements of Equity - Ohio (USD $) In Millions	Total	Retained Earnings [Member]	Net Gains (Losses) on Cash Flow Hedges [Member]	Pension And OPEB Related Adjustments To AOCI [Member]	Duke Energy Ohio [Member]	Duke Energy Ohio [Member] Common Stock [Member]	Duke Energy Ohio [Member] Additional Paid In Capital [Member]	Duke Energy Ohio [Member] Retained Earnings [Member]	Duke Energy Ohio [Member] Pension And OPEB Related Adjustments To AOCI [Member]
Balance at Dec. 31, 2010					$ 5,464	$ 762			$ (22)
Net income					157
Balance at Jun. 30, 2011
Balance at Dec. 31, 2010			8		5,464	762	5,570	(846)	(22)
Net income	1,424	1,418			157			157
Other comprehensive income, net of tax	(198)		(49)	(6)
Dividend to parent					(485)		(485)
Balance at Sep. 30, 2011					5,136	762	5,085	(689)	(22)
Balance at Jun. 30, 2011
Net income	470				51
Other comprehensive income, net of tax	(288)
Balance at Sep. 30, 2011					5,136	762			(22)
Balance at Dec. 31, 2011						762
Net income		1,333
Balance at Jun. 30, 2012
Balance at Dec. 31, 2011	22,772				5,167	762	5,085	(652)	(28)
Net income	1,345				133			133
Other comprehensive income, net of tax	(110)		(19)	(15)	1				1
Dividend to parent					0
Transfer of Vermillion Generating Station					(28)		(28)
Balance at Sep. 30, 2012	40,905				5,273	762	5,057	(519)	(27)
Balance at Jun. 30, 2012
Net income	598				14
Other comprehensive income, net of tax	(20)
Balance at Sep. 30, 2012	$ 40,905				$ 5,273	$ 762