Condensed Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Net income	$ 598		$ 470		$ 1,345		$ 1,424
Other comprehensive income(loss), net of tax
Foreign currency translation adjustments	2		(246)		(85)		(150)
Pension and OPEB related adjustments to AOCI	(21)	[1]	1	[1]	(15)	[1]	(6)	[1]
Net unrealized gain on cash flow hedges	(2)	[2]	(47)	[2]	(19)	[2]	(52)	[2]
Reclassification into earnings from cash flow hedges	(2)	[3]	1	[3]	0	[3]	3	[3]
Unrealized gain (loss) on investments in auction rate securities	1	[4]	3	[4]	7	[4]	7	[4]
Unrealized gain on investments in auction rate securities and other available for sale securities	3	[5]	0	[5]	6	[5]	0	[5]
Reclassification into earnings from available for sale securities	(1)	[6]	0	[6]	(4)	[6]	0	[6]
Other comprehensive income, net of tax	(20)		(288)		(110)		(198)
Comprehensive income	578		182		1,235		1,226
Comprehensive Income attributable to noncontrolling interests	4		(13)		8		(2)
Comprehensive income attributable to Duke Energy Corporation	574		195		1,227		1,228
Duke Energy Carolinas [Member]
Net income	258		311		735		709
Other comprehensive income(loss), net of tax
Reclassification into earnings from cash flow hedges	0	[7]	(2)	[7]	(2)	[7]	(3)	[7]
Other comprehensive income, net of tax					2		3
Comprehensive income attributable to Duke Energy Corporation	258		313		737		712
Duke Energy Ohio [Member]
Net income	14		51		133		157
Other comprehensive income(loss), net of tax
Pension and OPEB related adjustments to AOCI	0	[8]	(1)	[8]	1	[8]	0	[8]
Other comprehensive income, net of tax					1
Comprehensive income attributable to Duke Energy Corporation	14		50		134		157
Duke Energy Indiana [Member]
Net income	(19)		(31)		(109)		113
Other comprehensive income(loss), net of tax
Reclassification into earnings from cash flow hedges	1				1	[9]	1
Other comprehensive income, net of tax					(1)		(1)
Comprehensive income attributable to Duke Energy Corporation	$ (19)		$ (32)		$ (110)		$ 112

[1] Net of $10 million tax benefit and $7 million tax benefit for the three and nine months ended September 30, 2012 and insignificant tax expense and $3 tax benefit for the three and nine months ended September 30, 2011.

[2] Net of $1 million tax benefit and $10 million tax benefit for the three and nine months ended September 30, 2012 and $26 million tax benefit and $28 million tax benefit for the three and nine months ended September 30, 2011.

[3] Net of insignificant tax benefit for each of the three and nine months ended September 30, 2012 and insignificant tax expense and $1 million tax expense for the three and nine months ended September 30, 2011, respectively.

[4] Net of $1 million tax benefit and $2 million tax expense for the three and nine months ended September 30, 2012 and $5 million tax expense and $6 million tax expense for the three and nine months ended September 30, 2011.

[5] Net of $2 million tax expense for the three and nine months ended September 30, 2012.

[6] Net of $2 million tax benefit for the three and nine months ended September 30, 2012.

[7] Net of insignificant tax expense and $2 million tax expense for the three and nine months ended September 30, 2012, and $1 million tax benefit and $1 million tax expense for the three and nine months ended September 30, 2011.

[8] Net of insignificant tax expense and $1 million tax expense for the three and nine months ended September 30, 2012, and $1 million tax benefit for the three months ended September 30, 2011.

[9] Net of insignificant tax benefit for the three and nine months ended September 30, 2012, and $1 million tax benefit for the three and nine months ended September 30, 2011.