Consolidated Statements of Equity - Ohio (USD $) In Millions	Total	Retained Earnings [Member]	Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member]	Accumulated Defined Benefit Plans Adjustment [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] Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member]	Duke Energy Ohio [Member] Accumulated Defined Benefit Plans Adjustment [Member]
Balance at Dec. 31, 2009					$ 5,898	$ 762	$ 5,570	$ (405)	$ 1	$ (30)
Net income	1,323	1,320			(441)			(441)
Other comprehensive income (loss), net of tax	373		4	276	7				(1)	8
Distributions to parent					0
Balance at Dec. 31, 2010					5,464	762		(846)	0	(22)
Net income	513				73
Balance at Mar. 31, 2011
Balance at Dec. 31, 2010					5,464	762	5,570	(846)		(22)
Net income	1,714	1,706			194			194
Other comprehensive income (loss), net of tax	(243)		(53)	(49)	(6)					(6)
Distributions to parent					485		(485)
Balance at Dec. 31, 2011	22,772				5,167	762	5,085	(652)		(28)
Balance at Sep. 30, 2011
Net income	290				37
Balance at Dec. 31, 2011	22,772				5,167	762
Net income	299				74
Balance at Mar. 31, 2012
Balance at Dec. 31, 2011	22,772				5,167	762	5,085	(652)		(28)
Net income	1,782	1,768			175			175
Other comprehensive income (loss), net of tax	(76)		(29)	19	27					27
Distributions to parent					175		(175)
Transfer of Vermillion Generating Station					28		(28)
Balance at Dec. 31, 2012	40,863				5,166	762	4,882	(477)		(1)
Balance at Sep. 30, 2012
Net income	437				42
Balance at Dec. 31, 2012	$ 40,863				$ 5,166	$ 762