Condensed Consolidated Statements of Member's Equity and Comprehensive Income - Carolinas (USD $) In Millions		Duke Energy Carolinas [Member] Member's Equity [Member]	Duke Energy Carolinas [Member] Net Gains (Losses) on Cash Flow Hedges [Member]		Duke Energy Carolinas [Member] Other [Member]		Duke Energy Carolinas [Member]		Net Gains (Losses) on Cash Flow Hedges [Member]		Other [Member]		Total
Balance at Dec. 31, 2009		$ 8,304	$ (24)		$ (9)		$ 8,271
Net income (loss)		394					394						228
Other Comprehensive Income (Loss)
Reclassification into earnings from cash flow hedges			1	[1]			1	[1]	(2)	[2]			(2)	[2]
Unrealized gain on investments of auction rate securities					1	[3]	1	[3]			6	[4]	6	[4]
Total Comprehensive Income (Loss)							396						206
Distribution to parent		(350)					(350)
Balance at Jun. 30, 2010		8,348	(23)		(8)		8,317
Balance at Mar. 31, 2010
Net income (loss)							202						(217)
Other Comprehensive Income (Loss)
Reclassification into earnings from cash flow hedges	[5]												1
Unrealized gain on investments of auction rate securities	[6]												3
Total Comprehensive Income (Loss)													(234)
Balance at Jun. 30, 2010							8,317
Balance at Dec. 31, 2010		8,938	(20)		(2)		8,916
Net income (loss)		398					398						954
Other Comprehensive Income (Loss)
Reclassification into earnings from cash flow hedges			1	[1]			1	[1]	(2)	[2]			(2)	[2]
Unrealized gain on investments of auction rate securities	[4]										4		4
Total Comprehensive Income (Loss)							399						1,044
Balance at Jun. 30, 2011		9,336	(19)		(2)		9,315
Balance at Mar. 31, 2011
Net income (loss)							193						441
Other Comprehensive Income (Loss)
Reclassification into earnings from cash flow hedges	[7]												1
Unrealized gain on investments of auction rate securities	[8]												1
Total Comprehensive Income (Loss)													503
Balance at Jun. 30, 2011					$ (2)		$ 9,315

[1] Net of $2 tax expense in 2011 and $1 tax expense in 2010.

[2] Net of $1 tax expense in 2011 and insignificant tax benefit in 2010.

[3] Net of $1 tax expense in 2010.

[4] Net of $1 tax expense in 2011 and $4 tax expense in 2010.

[5] Net of insignificant tax benefit.

[6] Net of $2 million tax expense.

[7] Net of $1 million tax expense.

[8] Net of $2 million tax benefit.