CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

Components for cash, cash equivalents and marketable securities (in millions):



September 30, 2013	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	3	$	—	$	—		$	3
Cash equivalents	38		—		—			38
Cash and cash equivalents	41		—		—			41
U.S. government and agency securities	393		1		(1		)	393
Foreign government bonds	24		—		—			24
Asset-back securities	129		—		—			129
Mortgage-back securities	134		—		(1		)	133
Corporate notes and bonds	693		5		(3		)	695
Municipal securities	30		—		—			30
Marketable securities	1,403		6		(5		)	1,404
Total	$	1,444	$	6	$	(5	)	$	1,445



December 31, 2012	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	28	$	—	$	—		$	28
Cash equivalents	94		—		—			94
Cash and cash equivalents	122		—		—			122
U.S. government and agency securities	271		1		—			272
Foreign government bonds	50		1		—			51
Asset-back securities	61		1		—			62
Mortgage-back securities	137		1		(1		)	137
Corporate notes and bonds	577		8		—			585
Municipal securities	23		—		—			23
Marketable securities	1,119		12		(1		)	1,130
Total	$	1,241	$	12	$	(1	)	$	1,252

Unrealized losses from fixed-income securities are primarily attributable to changes in interest rates. Management does not believe any remaining unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of September 30, 2013.

Activity for marketable securities (in millions):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013			2012
Proceeds from sales and maturities	$	247	$	271	$	712		$	701
Gross realized gains	—		2		3			6
Gross realized losses	—		—		(1		)	(1		)

Marketable securities maturities (in millions):



September 30, 2013	Cost Basis		Fair Value
Due in one year or less	$	198	$	199
Due after one year through five years	1,187		1,187
Due after five years through 10 years	18		18
Total	$	1,403	$	1,404