CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

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



December 31, 2013	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	9	$	—	$	—		$	9
Cash equivalents	71		—		—			71
Cash and cash equivalents	80		—		—			80
U.S. government and agency securities	295		1		(2		)	294
Foreign government bonds	11		—		—			11
Asset-back securities	146		—		—			146
Mortgage-back securities	144		1		(2		)	143
Corporate notes and bonds	628		4		(2		)	630
Municipal securities	26		—		—			26
Marketable securities	1,250		6		(6		)	1,250
Total	$	1,330	$	6	$	(6	)	$	1,330



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 December 31, 2013.

Activity for marketable securities for the years ended December 31 (in millions):



	2013			2012			2011
Proceeds from sales and maturities	$	1,089		$	1,048		$	956
Gross realized gains	4			9			8
Gross realized losses	(2		)	(2		)	(3		)
Other-than-temporary impairments on investments	—			—			(2		)

Marketable securities maturities as of December 31, 2013 (in millions):



December 31, 2013	Cost Basis		Fair Value
Due in one year or less	$	111	$	111
Due after one year through five years	1,117		1,118
Due after five years through 10 years	22		21
Total	$	1,250	$	1,250