Condensed Consolidated Statements of Common Stockholder's Equity and Comprehensive Income - Ohio (USD $) In Millions		Duke Energy Ohio [Member] Common Stock [Member]	Duke Energy Ohio [Member] Additional Paid-in Capital [Member]	Duke Energy Ohio [Member] Retained Earnings (Deficit) [Member]	Duke Energy Ohio [Member] Net Gains (Losses) on Cash Flow Hedges [Member]	Duke Energy Ohio [Member] Pension and OPEB Related Adjustments to AOCI [Member]		Duke Energy Ohio [Member]		Retained Earnings (Deficit) [Member]	Pension and OPEB Related Adjustments to AOCI [Member]		Total
Balance at Dec. 31, 2009		$ 762	$ 5,570	$ (405)	$ 1	$ (30)		$ 5,898
Net income (loss)				(629)				(629)		223			228
Other Comprehensive Income (Loss)
Pension and OPEB related adjustments to AOCI						1	[1]	1	[1]		15	[2]	15	[2]
Total Comprehensive Income (Loss)								(628)					206
Balance at Jun. 30, 2010		762	5,570	(1,034)	1	(29)		5,270
Balance at Mar. 31, 2010
Net income (loss)								(759)					(217)
Other Comprehensive Income (Loss)
Pension and OPEB related adjustments to AOCI	[3]												2
Total Comprehensive Income (Loss)													(234)
Balance at Jun. 30, 2010		762	5,570		1			5,270
Balance at Dec. 31, 2010		762	5,570	(846)		(22)		5,464					22,522
Net income (loss)				106				106		946			954
Other Comprehensive Income (Loss)
Pension and OPEB related adjustments to AOCI						1	[1]	1	[1]		(7)	[2]	(7)	[2]
Total Comprehensive Income (Loss)								107					1,044
Capital contribution to parent			(285)					(285)
Balance at Jun. 30, 2011		762	5,285	(740)		(21)		5,286					22,583
Balance at Mar. 31, 2011
Net income (loss)								33					441
Other Comprehensive Income (Loss)
Pension and OPEB related adjustments to AOCI	[4]												2
Total Comprehensive Income (Loss)													503
Balance at Jun. 30, 2011		$ 762						$ 5,286					$ 22,583

[1] Net of $1 tax expense in both 2011 and 2010.

[2] Net of $3 tax benefit in 2011 and $5 tax expense in 2010.

[3] Net of $1 million tax expense.

[4] Net of insignificant tax expense.