CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

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



September 30, 2015	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	3	$	—	$	—		$	3
Cash equivalents	85		—		—			85
Cash and cash equivalents	88		—		—			88
U.S. government and agency securities	188		1		—			189
Foreign government bonds	31		—		—			31
Asset-backed securities	137		—		—			137
Mortgage-backed securities	107		—		—			107
Corporate notes and bonds	682		5		(3		)	684
Municipal securities	22		—		—			22
Marketable securities	1,167		6		(3		)	1,170
Total	$	1,255	$	6	$	(3	)	$	1,258



December 31, 2014	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	4	$	—	$	—		$	4
Cash equivalents	103		—		—			103
Cash and cash equivalents	107		—		—			107
U.S. government and agency securities	166		—		—			166
Foreign government bonds	25		—		—			25
Asset-backed securities	130		—		—			130
Mortgage-backed securities	127		—		(1		)	126
Corporate notes and bonds	644		3		(2		)	645
Municipal securities	18		—		—			18
Marketable securities	1,110		3		(3		)	1,110
Total	$	1,217	$	3	$	(3	)	$	1,217

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, 2015.

Activity for marketable securities (in millions):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015			2014
Proceeds from sales and maturities	$	142	$	341	$	818		$	739
Gross realized gains	—		1		2			3
Gross realized losses	—		—		(2		)	(1		)

Maturities for marketable securities (in millions):



September 30, 2015	Cost Basis		Fair Value
Due in one year or less	$	171	$	171
Due after one year through five years	993		995
Due after five years through 10 years	3		4
Due after 10 years	—		—
Total	$	1,167	$	1,170