Condensed Consolidated Statements Of Common Stockholder's 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
Dividend to parent					285
Balance at Mar. 31, 2011
Balance at Dec. 31, 2010			8		5,464	762	5,570	(846)	(22)
Net income	954	946			106			106
Other comprehensive income, net of tax	90		(3)	(7)	1				1
Dividend to parent					(285)		(285)
Balance at Jun. 30, 2011					5,286	762	5,285	(740)	(21)
Balance at Mar. 31, 2011
Net income	441				33
Other comprehensive income, net of tax	62
Balance at Jun. 30, 2011					5,286	762
Balance at Dec. 31, 2011	22,772				5,167	762	5,085	(652)	(28)
Net income	747	739			119			119
Other comprehensive income, net of tax	(90)		(15)	6	1				1
Dividend to parent					0
Transfer of Vermillion Generating Station					(28)		(28)
Balance at Jun. 30, 2012	22,419				5,259	762	5,057	(533)	(27)
Balance at Mar. 31, 2012
Net income	448				45
Other comprehensive income, net of tax	(150)
Balance at Jun. 30, 2012	$ 22,419				$ 5,259	$ 762