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	Jun. 30, 2011		Dec. 31, 2010
Location and fair value amounts of derivatives (Asset)	$ 236		$ 322
Location and fair value amounts of derivatives (Liability)	209		268
Designated as Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)	15		21
Location and fair value amounts of derivatives (Liability)	13		13
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	3		5
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Investments and Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	12		16
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Liability)	13		13
Not Designated as Hedging Instrument [Member]
Location and fair value amounts of derivatives (Asset)	221		301
Location and fair value amounts of derivatives (Liability)	196		255
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	50	[1]
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)	4		5
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	107		108
Location and fair value amounts of derivatives (Liability)	56		54
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Investments and Other Assets, Other [Member]
Location and fair value amounts of derivatives (Asset)	44		55
Location and fair value amounts of derivatives (Liability)	4		4
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Location and fair value amounts of derivatives (Asset)	13		75
Location and fair value amounts of derivatives (Liability)	48		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)	7		3
Location and fair value amounts of derivatives (Liability)	$ 82		$ 72

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