Condensed Consolidated Statements Of Common Stockholder's Equity And Comprehensive Income - Ohio (USD $) In Millions, unless otherwise specified		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] Net (Losses) Gains On Cash Flow Hedges [Member]		Duke Energy Ohio [Member] Pension And OPEB Related Adjustments To AOCI [Member]		Duke Energy Ohio [Member]		Retained Earnings [Member]	Net (Losses) Gains On Cash Flow Hedges [Member]		Pension And OPEB Related Adjustments To AOCI [Member]		Total
Balance at Dec. 31, 2008		$ 762	$ 5,570	$ 381	$ (15)		$ (28)		$ 6,670
Net income (loss)				(426)					(426)		1,075					1,085
Other comprehensive income (loss)
Reclassification into earnings from cash flow hedges					16	[1]			16	[1]		(18)	[2]			(18)	[2]
Pension and OPEB related adjustments to AOCI							(2)	[3]	(2)	[3]				36	[4]	36	[4]
Total comprehensive income (loss)									(412)							1,457
Dividends to parent				(360)					(360)
Balance at Dec. 31, 2009		762	5,570	(405)	1		(30)		5,898
Net income (loss)				(441)					(441)		1,320					1,323
Other comprehensive income (loss)
Reclassification into earnings from cash flow hedges					(1)	[1]			(1)	[1]		(3)	[2]			(3)	[2]
Pension and OPEB related adjustments to AOCI							8	[3]	8	[3]				276	[4]	276	[4]
Total comprehensive income (loss)									(434)							1,696
Dividends to parent
Balance at Dec. 31, 2010		762	5,570	(846)			(22)		5,464							22,522
Net income (loss)				194					194		1,706					1,714
Other comprehensive income (loss)
Reclassification into earnings from cash flow hedges	[2]											(4)				(4)
Pension and OPEB related adjustments to AOCI							(6)	[3]	(6)	[3]				(49)	[4]	(49)	[4]
Total comprehensive income (loss)									188							1,471
Dividends to parent			(485)						(485)
Balance at Dec. 31, 2011		$ 762	$ 5,085	$ (652)			$ (28)		$ 5,167							$ 22,772

[1] Net of $1 tax benefit in 2010 and $8 tax expense in 2009.

[2] Net of $1 tax expense in 2011, insignificant tax expense in 2010 and $10 tax expense in 2009.

[3] Net of insignificant tax expense in 2011, $4 tax expense in 2010 and $1 tax expense in 2009.

[4] Net of $23 tax benefit in 2011, $150 tax expense in 2010 and $16 tax expense in 2009.