Condensed Consolidated Statements Of Member's Equity and Comprehensive Income - Carolinas (USD $) In Millions, unless otherwise specified		Duke Energy Carolinas [Member] Partnership Interest [Member]	Duke Energy Carolinas [Member] Net (Losses) Gains On Cash Flow Hedges [Member]		Duke Energy Carolinas [Member] Other Equity [Member]		Duke Energy Carolinas [Member]		Net (Losses) Gains On Cash Flow Hedges [Member]		Other Equity [Member]		Total
Balance at Dec. 31, 2008		$ 7,349	$ (27)		$ (6)		$ 7,316
Net income (loss)		702					702						1,085
Other comprehensive income (loss)
Unrealized gain on investments in auction rate securities					(3)	[1]	(3)	[1]			(6)	[2]	(6)	[2]
Reclassification into earnings from cash flow hedges			3	[3]			3	[3]	(18)	[4]			(18)	[4]
Total comprehensive income (loss)							702						1,457
Distributions/Dividends to parent		3					3
Capital contribution from parent		250					250
Balance at Dec. 31, 2009		8,304	(24)		(9)		8,271
Net income (loss)		838					838						1,323
Other comprehensive income (loss)
Unrealized gain on investments in auction rate securities					7	[1]	7	[1]			14	[2]	14	[2]
Reclassification into earnings from cash flow hedges			4	[3]			4	[3]	(3)	[4]			(3)	[4]
Total comprehensive income (loss)							849						1,696
Allocation of Net Pension and Other Post-retirement Assets From Parent		146					146
Distributions/Dividends to parent		(350)					(350)
Balance at Dec. 31, 2010		8,938	(20)		(2)		8,916
Net income (loss)		834					834						1,714
Other comprehensive income (loss)
Unrealized gain on investments in auction rate securities	[2]										8		8
Reclassification into earnings from cash flow hedges			3	[3]			3	[3]	(4)	[4]			(4)	[4]
Total comprehensive income (loss)							837						1,471
Distributions/Dividends to parent		(299)					(299)
Balance at Dec. 31, 2011		$ 9,473	$ (17)		$ (2)		$ 9,454

[1] Net of $5 tax expense in 2010 and $3 tax benefit in 2009.

[2] Net of $4 tax expense in 2011, $8 tax expense in 2010 and $4 tax benefit in 2009.

[3] Net of $2 tax expense in 2011, 2010 and 2009.

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