Financial Instruments

Cash, Cash Equivalents and Marketable Securities

The following tables summarize our cash and available-for-sale securities by significant investment category.



	September 26, 2014
(In thousands)	Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Short-Term Marketable Securities		Long-Term Marketable Securities

Cash	$	86,058	$	—	$	—		$	86,058	$	86,058	$	—	$	—

Available-for-sale:
Level 1:
Money market funds	2,575,403		—		—			2,575,403		2,575,403		—		—
U.S. treasury securities	1,641,228		1,762		(8,059		)	1,634,931		18,624		45,038		1,571,269
Subtotal	4,216,631		1,762		(8,059		)	4,210,334		2,594,027		45,038		1,571,269

Level 2:
U.S. agency securities	27,379		23		(5		)	27,397		—		11,215		16,182
Non-U.S. government securities	18,610		5		(2		)	18,613		—		17,080		1,533
Municipal bonds	2,000		1		(2		)	1,999		—		—		1,999
Corporate debt securities	214,217		448		(92		)	214,573		—		60,726		153,847
Subtotal	262,206		477		(101		)	262,582		—		89,021		173,561
Total	$	4,564,895	$	2,239	$	(8,160	)	$	4,558,974	$	2,680,085	$	134,059	$	1,744,830



	December 31, 2013
(In thousands)	Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Short-Term Marketable Securities		Long-Term Marketable Securities

Cash	$	71,880	$	—	$	—		$	71,880	$	71,880	$	—	$	—

Available-for-sale:
Level 1:
Money market funds	2,763,094		—		—			2,763,094		2,763,094		—		—
U.S. treasury securities	1,604,450		15		(28,298		)	1,576,167		34,184		39,262		1,502,721
Subtotal	4,367,544		15		(28,298		)	4,339,261		2,797,278		39,262		1,502,721

Level 2:
U.S. agency securities	53,755		33		(18		)	53,770		—		26,999		26,771
Non-U.S. government securities	18,352		5		—			18,357		—		9,306		9,051
Municipal bonds	2,603		—		(7		)	2,596		—		603		1,993
Corporate debt securities	219,491		425		(69		)	219,847		—		65,317		154,530
Subtotal	294,201		463		(94		)	294,570		—		102,225		192,345
Total	$	4,733,625	$	478	$	(28,392	)	$	4,705,711	$	2,869,158	$	141,487	$	1,695,066

We have made certain cost method investments of approximately $20.6 million. These investments are included within Other assets, net in our consolidated balance sheets. The investments are in privately held companies in which we have less than a 20% interest and no significant influence over the investees' operations. We report these investments at cost, except when investments are found to be more than temporarily impaired after an impairment review.

The adjusted cost and estimated fair value of marketable debt securities (corporate debt securities, municipal bonds, U.S. and foreign government securities, and U.S. treasury securities) as of September 26, 2014, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations without call or prepayment penalties.



	September 26, 2014
(In thousands)	Cost		Estimated Fair Value
Due in one year or less	$	152,554	$	152,683
Due after one year through five years	1,351,050		1,343,299
Due between six and ten years	399,830		401,531
	$	1,903,434	$	1,897,513

As of September 26, 2014, we had 113 securities, or $1.2 billion out of our total available-for-sale securities investment portfolio, that were in a continuous unrealized loss position for less than 12 months with a gross unrealized loss of $8.2 million. As of December 31, 2013, we had 137 securities, or $1.6 billion out of our total available-for-sale securities investment portfolio, that were in a continuous unrealized loss position for less than 12 months with a gross unrealized loss of $28.4 million.

We concluded that the declines in market value of our available-for-sale securities investment portfolio were temporary in nature and did not consider any of our investments to be other-than-temporarily impaired.