Consolidated Statements of Equity - Carolinas (USD $) In Millions	Total	Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member]	Other Equity [Member]	Duke Energy Carolinas [Member]	Duke Energy Carolinas [Member] Members Equity [Member]	Duke Energy Carolinas [Member] Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member]	Duke Energy Carolinas [Member] Other Equity [Member]
Balance at Dec. 31, 2009				$ 8,271	$ 8,304	$ (24)	$ (9)
Net income	1,323			838	838
Other comprehensive income (loss), net of tax	373	4	14	11		4	7
Allocation Of Net Pension And Other Post Retirement Assets From Parent				146	146
Distributions to parent				350	(350)
Balance at Dec. 31, 2010				8,916	8,938	(20)	(2)
Net income	513			205
Balance at Mar. 31, 2011
Balance at Dec. 31, 2010				8,916	8,938	(20)
Net income	1,714			834	834
Other comprehensive income (loss), net of tax	(243)	(53)	8	3		3
Distributions to parent				299	(299)
Balance at Dec. 31, 2011				9,454	9,473	(17)
Balance at Sep. 30, 2011
Net income	290			125
Balance at Dec. 31, 2011				9,454
Net income	299			266
Balance at Mar. 31, 2012
Balance at Dec. 31, 2011				9,454	9,473	(17)	(2)
Net income	1,782			865	865
Other comprehensive income (loss), net of tax	(76)	(29)	9	3		2	1
Distributions to parent				450	(450)
Balance at Dec. 31, 2012				9,872	9,888	(15)	(1)
Balance at Sep. 30, 2012
Net income	437			130
Balance at Dec. 31, 2012				$ 9,872