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	Mar. 31, 2012		Dec. 31, 2011
Location and fair value amounts of derivatives (Asset)	$ 271		$ 283
Location and fair value amounts of derivatives (Liability)	422		473
Designated As Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)			6
Location and fair value amounts of derivatives (Liability)			87
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member]
Location and fair value amounts of derivatives (Asset)	7
Location and fair value amounts of derivatives (Liability)	72
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	5		4
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Investments And Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	2		2
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	11		11
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	61		76
Not Designated As Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)	264		277
Location and fair value amounts of derivatives (Liability)	350		386
Not Designated As Hedging Instrument [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)			2
Not Designated As Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)			75	[1]
Not Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	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)	53	[2]
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	206		81
Location and fair value amounts of derivatives (Liability)	138		31
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Investments And Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	22		35
Location and fair value amounts of derivatives (Liability)			17
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Asset)	4		136
Location and fair value amounts of derivatives (Liability)	55		168
Not Designated As Hedging Instrument [Member] | Commodity Contracts [Member] | Deferred Credits And Other Liabilities, Other [Member]
Location and fair value amounts of derivatives (Asset)	32		25
Location and fair value amounts of derivatives (Liability)	$ 102		$ 93

[1] Amounts at Duke Energy include $67 million related to interest rate swaps at Duke Energy Indiana which receive regulatory accounting treatment.

[2] Amount at Duke Energy includes $48 million related to interest rate swaps at Duke Energy Indiana which receive regulatory accounting treatment.