Condensed Consolidated Statements Of Equity And Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net unrealized gains (losses) on cash flow hedges, tax benefit (expense)	$ 31	$ (1)	$ (1)
Reclassification into earnings from cash flow hedges, tax benefit (expense)	(1)		(10)
Net actuarial loss, tax			12
Unrealized gain on investments in auction rate securities, tax benefit (expense)	(4)	(8)	4
Reclassification of gains on investments in available-for-sale securities into earnings, tax	2		(2)
Unrealized gain on investments in available-for-sale securities, tax	(3)		(4)
Pension and OPEB related adjustments to AOCI, tax benefit (expense)	23	(150)	(16)
Cash distributions paid to noncontrolling interests	26	10	37
Duke Energy Carolinas [Member]
Reclassification into earnings from cash flow hedges, tax benefit (expense)	(2)	(2)	(2)
Unrealized gain on investments in auction rate securities, tax benefit (expense)		(5)	3
Duke Energy Ohio [Member]
Reclassification into earnings from cash flow hedges, tax benefit (expense)		1	(8)
Pension and OPEB related adjustments to AOCI, tax benefit (expense)		(4)	(1)
Duke Energy Indiana [Member]
Reclassification into earnings from cash flow hedges, tax benefit (expense)	$ 1	$ 1	$ 1