Derivatives (Tables)

12 Months Ended

Dec. 31, 2011

Derivatives [Abstract]

Energy-related derivative contracts

Power			Gas
Net Purchased Megawatt-hours	Longest Hedge Date	Longest Non-Hedge Date	Net Purchased mmBtu*	Longest Hedge Date	Longest Non-Hedge Date
(in millions)			(in millions)
1	2012	2012	189	2017	2017

Notional amount of interest rate derivatives

	Notional Amount		Interest Rate Received	Interest Rate Paid*	Hedge Maturity Date	Fair Value Gain (Loss) December 31, 2011
	(in millions)					(in millions)
Cash flow hedges of forecasted debt
	$	100	3-month LIBOR	2.22%	January 2022	$	(1	)
		300	3-month LIBOR	2.90%	December 2022		(17	)
		300	3-month LIBOR	2.66%	April 2022		(15	)
Fair value hedges of existing debt
		350	4.15%	3-month LIBOR + 1.96% spread	May 2014		13
Total	$	1,050				$	(20	)

* Weighted Average

Outstanding foreign currency derivatives

	Notional Amount	Forward Rate	Hedge Maturity Date	Fair Value Gain (Loss) December 31, 2011
	(in millions)			(in millions)
Fair value hedges of firm commitments
	EUR9.2	1.371 Dollars per Euro*	Various through March 2014	$	(1	)
Derivatives not designated as hedges
	EUR18.1	1.317 Dollars per Euro*	N/A		—
Total				$	(1	)

* Weighted Average

Fair value of energy-related derivatives and interest rate derivatives

	Asset Derivatives					Liability Derivatives
Derivative Category	Balance Sheet Location	2011		2010		Balance Sheet Location	2011		2010
		(in millions)					(in millions)
Derivatives designated as hedging instruments for regulatory purposes
Energy-related derivatives:	Other current assets		$  9		$  4	Liabilities from risk management activities		$163		$145
	Other deferred charges and assets		5		3	Other deferred credits and liabilities		72		55
Total derivatives designated as hedging instruments for regulatory purposes			$14		$  7			$235		$200
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:	Other current assets		$—		$—	Liabilities from risk management activities		$    1		$    1
Interest rate derivatives:	Other current assets		6		6	Liabilities from risk management activities		33		1
	Other deferred charges and assets		7		4	Other deferred credits and liabilities		—		—
Foreign currency derivatives:	Other current assets		—		2	Liabilities from risk management activities		1		—
	Other deferred charges and assets		—		1	Other deferred credits and liabilities		—		—
Total derivatives designated as hedging instruments in cash flow and fair value hedges			$13		$13			$  35		$    2
Derivatives not designated as hedging instruments
Energy-related derivatives:	Other current assets		$—		$  2	Liabilities from risk management activities		$    9		$    5
	Other deferred charges and assets		—		1	Other deferred credits and liabilities		—		—
Foreign currency derivatives	Other current assets		2		—	Liabilities from risk management activities		2		—
Total derivatives not designated as hedging instruments			$  2		$  3			$  11		$    5
Total			$29		$23			$281		$207

Pre-tax effect of unrealized derivative gains (losses)

	Unrealized Losses					Unrealized Gains
Derivative Category	Balance Sheet     Location	2011		2010		Balance Sheet       Location	2011		2010
		(in millions)					(in millions)
Energy-related derivatives:	Other regulatory assets, current		$(163)		$(145)	Other regulatory liabilities, current		$9		$4
	Other regulatory assets, deferred		(72)		(55)	Other regulatory liabilities, deferred		5		3
Total energy-related derivative gains (losses)			$(235)		$(200)			$14		$7

Pre-tax effect of derivatives designated as cash flow hedging instruments

Derivatives in Cash Flow Hedging Relationships	Gain (Loss) Recognized in OCI on Derivative (Effective Portion)						Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
								Amount
Derivative Category	2011		2010		2009		Statements of Income Location	2011	2010		2009
	(in millions)							(in millions)
Energy-related derivatives		$  —		$   1		$(2)	Fuel	$ —		$ —		$ —
Interest rate derivatives		(28)		(3)		(5)	Interest expense, net of amounts capitalized	(14)		(25)		(46)
Foreign currency derivatives		—		1		—	Other operations and maintenance	—		1		—
							Other income (expense), net	(1)		—		—
Total		$(28)		$ (1)		$(7)		$(15)		$(24)		$(46)

Pre-tax effect of energy-related derivatives not designated as hedging instruments

Derivatives not Designated as Hedging Instruments	Unrealized Gain (Loss) Recognized in Income
		Amount
Derivative Category	Statements of Income Location	2011	2010	2009
		(in millions)
Energy-related derivatives:	Wholesale revenues	$ 2	$ (2)	$ 5
	Fuel	(9)	1	(6)
	Purchased power	1	(1)	(4)
Total		$(6)	$(2)	$(5)