Condensed Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Net income	$ 448		$ 441		$ 747		$ 954
Other comprehensive income(loss), net of tax
Foreign currency translation adjustments	(131)		65		(87)		96
Pension and OPEB related adjustments to AOCI	2	[1]	2	[1]	6	[1]	(7)	[1]
Net unrealized gain on cash flow hedges	(30)	[2]	(7)	[2]	(17)	[2]	(5)	[2]
Reclassification into earnings from cash flow hedges	3	[3]	1	[3]	2	[3]	2	[3]
Unrealized gain (loss) on investments in auction rate securities	6	[4]	1	[4]	6	[4]	4	[4]
Unrealized gain on investments in auction rate securities and other available for sale securities	2	[5]	0	[5]	3	[5]	0	[5]
Reclassification into earnings from available for sale securities	(2)	[6]	0	[6]	(3)	[6]	0	[6]
Other comprehensive income, net of tax	(150)		62		(90)		90
Comprehensive income	298		503		657		1,044
Comprehensive Income attributable to noncontrolling interests	0		9		4		11
Comprehensive income attributable to Duke Energy Corporation	298		494		653		1,033
Duke Energy Carolinas [Member]
Net income	211		193		477		398
Other comprehensive income(loss), net of tax
Reclassification into earnings from cash flow hedges	(2)	[7]	(1)	[7]	(2)	[7]	(1)	[7]
Other comprehensive income, net of tax					2		1
Comprehensive income attributable to Duke Energy Corporation	213		194		479		399
Duke Energy Ohio [Member]
Net income	45		33		119		106
Other comprehensive income(loss), net of tax
Pension and OPEB related adjustments to AOCI	0	[8]	1	[8]	1	[8]	1	[8]
Other comprehensive income, net of tax					1		1
Comprehensive income attributable to Duke Energy Corporation	45		34		120		107
Duke Energy Indiana [Member]
Net income	77		68		(90)		144
Other comprehensive income(loss), net of tax
Reclassification into earnings from cash flow hedges					1	[6]
Other comprehensive income, net of tax					(1)
Comprehensive income attributable to Duke Energy Corporation	$ 77		$ 68		$ (91)		$ 144

[1] Net of $1 million tax expense and $3 million tax expense for the three and six months ended June 30, 2012 and insignificant tax expense and $3 tax benefit for the three and six months ended June 30, 2011.

[2] Net of $14 million tax benefit and $9 million tax benefit for the three and six months ended June 30, 2012 and $3 million tax benefit and $2 million tax benefit for the three and six months ended June 30, 2011.

[3] Net of $2 million tax benefit and insignificant tax expense for the three and six months ended June 30, 2012 and $1 million tax expense for the three and six months ended June 30, 2011, respectively.

[4] Net of $2 million tax expense and $3 million tax expense for the three and six months ended June 30, 2012 and $2 million tax benefit and $1 million tax expense for the three and six months ended June 30, 2011.

[5] Net of insignificant tax expense for the three and six months ended June 30, 2012.

[6] Net of insignificant tax benefit for the three and six months ended June 30, 2012.

[7] Net of $2 million tax expense for the three and six months ended June 30, 2012 and 2011.

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