Investments In Unconsolidated Affiliates And Related Party Transactions (Equity In Earnings Of Equity Method Unconsolidated Affiliates) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Equity in earnings (losses) of unconsolidated affiliates	$ 160	[1]	$ 116	[1]	$ 70	[1]
U.S. Franchised Electric And Gas [Member]
Equity in earnings (losses) of unconsolidated affiliates					(10)	[1]
Commercial Power [Member]
Equity in earnings (losses) of unconsolidated affiliates	6	[1]	7	[1]	7	[1]
International Energy [Member]
Equity in earnings (losses) of unconsolidated affiliates	145	[1]	102	[1]	72	[1]
Other Investment Companies [Member]
Equity in earnings (losses) of unconsolidated affiliates	9	[1]	7	[1]	1	[1]
Domestic Equity Method Investments [Member]
Equity in earnings (losses) of unconsolidated affiliates	13		12		(3)
Domestic Equity Method Investments [Member] | U.S. Franchised Electric And Gas [Member]
Equity in earnings (losses) of unconsolidated affiliates					(10)
Domestic Equity Method Investments [Member] | Commercial Power [Member]
Equity in earnings (losses) of unconsolidated affiliates	6		7		7
Domestic Equity Method Investments [Member] | Other Investment Companies [Member]
Equity in earnings (losses) of unconsolidated affiliates	7		5
International Equity Method Investments [Member]
Equity in earnings (losses) of unconsolidated affiliates	147		104		73
International Equity Method Investments [Member] | International Energy [Member]
Equity in earnings (losses) of unconsolidated affiliates	145		102		72
International Equity Method Investments [Member] | Other Investment Companies [Member]
Equity in earnings (losses) of unconsolidated affiliates	$ 2		$ 2		$ 1

[1] Duke Energy's share of net earnings from these unconsolidated affiliates is reflected in the Consolidated Statements of Operations as Equity in Earnings of Unconsolidated Affiliates.