Risk Management, Derivative Instruments And Hedging Activities (Location And Fair Value Amounts Of Derivatives Reflected In The Condensed Consolidated Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Designated As Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)	$ 6		$ 21
Location and fair value amounts of derivatives (Liability)	87		13
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	4		5
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Investments And Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	2		16
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	11		13
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	76
Not Designated As Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)	277		301
Location and fair value amounts of derivatives (Liability)	386		255
Not Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Investments And Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)			60	[1]
Not Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	2		2
Not Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	75	[2]	5	[2]
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	81		108
Location and fair value amounts of derivatives (Liability)	31		54
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Investments And Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	35		55
Location and fair value amounts of derivatives (Liability)	17		4
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Asset)	136		75
Location and fair value amounts of derivatives (Liability)	168		118
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Asset)	25		3
Location and fair value amounts of derivatives (Liability)	$ 93		$ 72

[1] Balance relates to interest rate swaps at Duke Energy Carolinas which receive regulatory accounting treatment.

[2] As of December 31, 2011, includes $67 million related to interest rate swaps at Duke Energy Indiana which receive regulatory accounting treatment.