Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value of Assets and Liabilities Measured on Recurring Basis

Our assets and liabilities that are measured at fair value on a recurring basis include the following (in millions):

			Fair Value Measurements at September 30, 2012 Using
	Total		Quoted Prices  in Active Markets (Level  1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	270	$	270	$	—	$	—
Available-for-sale securities		164		139		—		25
Electricity commodity derivatives		1		—		1		—
Total assets	$	435	$	409	$	1	$	25
Liabilities:
Electricity commodity derivatives	$	4	$	—	$	4	$	—
Foreign exchange derivatives		16		—		16		—
Interest rate derivatives		42		—		42		—
Total liabilities	$	62	$	—	$	62	$	—

			Fair Value Measurements at December 31, 2011 Using
	Total		Quoted Prices  in Active Markets (Level  1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	120	$	120	$	—	$	—
Available-for-sale securities		179		154		—		25
Interest rate derivatives		73		—		73		—
Electricity commodity derivatives		5		—		5		—
Total assets	$	377	$	274	$	78	$	25
Liabilities:
Interest rate derivatives	$	74	$	—	$	74	$	—
Foreign exchange derivatives		2		—		2		—
Total liabilities	$	76	$	—	$	76	$	—