CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

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



June 30, 2013	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	4	$	—	$	—		$	4
Cash equivalents	53		—		—			53
Cash and cash equivalents	57		—		—			57
U.S. government and agency securities	412		—		(3		)	409
Foreign government bonds	24		—		—			24
Asset-back securities	120		—		—			120
Mortgage-back securities	141		1		(1		)	141
Corporate notes and bonds	657		4		(4		)	657
Municipal securities	21		—		—			21
Marketable securities	1,375		5		(8		)	1,372
Total	$	1,432	$	5	$	(8	)	$	1,429



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 June 30, 2013.

Activity for marketable securities (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013			2012
Proceeds from sales and maturities	$	226	$	242	$	465		$	430
Gross realized gains	1		2		3			4
Gross realized losses	—		—		(1		)	(1		)

Marketable securities maturities (in millions):



June 30, 2013	Cost Basis		Fair Value
Due in one year or less	$	232	$	232
Due after one year through five years	1,140		1,137
Due after five years through 10 years	3		3
Total	$	1,375	$	1,372