CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

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



March 31, 2014	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	5	$	—	$	—		$	5
Cash equivalents	85		—		—			85
Cash and cash equivalents	90		—		—			90
U.S. government and agency securities	284		—		(1		)	283
Foreign government bonds	18		—		—			18
Asset-back securities	158		—		—			158
Mortgage-back securities	146		1		(1		)	146
Corporate notes and bonds	696		5		(1		)	700
Municipal securities	25		—		—			25
Marketable securities	1,327		6		(3		)	1,330
Total	$	1,417	$	6	$	(3	)	$	1,420



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

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 March 31, 2014.

Activity for marketable securities (in millions):



	Three Months Ended March 31,
	2014			2013
Proceeds from sales and maturities	$	227		$	239
Gross realized gains	1			2
Gross realized losses	(1		)	(1		)

Maturities for marketable securities (in millions):



March 31, 2014	Cost Basis		Fair Value
Due in one year or less	$	144	$	145
Due after one year through five years	1,176		1,178
Due after five years through 10 years	7		7
Total	$	1,327	$	1,330