Marketable Securities

The Company accounts for its marketable securities as AFS. The Company recorded $2.8 million and $2.5 million of net unrealized loss in AOCI as of December 30, 2018, and December 31, 2017, respectively.

The following tables present the amortized cost, gross unrealized gains and losses, and fair market value of our AFS securities as of December 30, 2018, and December 31, 2017:



	December 30, 2018
(In thousands)	Amortized Cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Short-term AFS securities
Corporate debt securities	$	140,631	$	1	$	(464	)	$	140,168
U.S. Treasury securities	107,717		—		(232		)	107,485
U.S. governmental agency securities	92,628		—		(654		)	91,974
Certificates of deposit	23,497		—		—			23,497
Commercial paper	8,177		—		—			8,177
Total short-term AFS securities	$	372,650	$	1	$	(1,350	)	$	371,301
Long-term AFS securities
Corporate debt securities	$	130,612	$	44	$	(1,032	)	$	129,624
U.S. Treasury securities	47,079		5		(347		)	46,737
U.S. governmental agency securities	37,362		3		(168		)	37,197
Total long-term AFS securities	$	215,053	$	52	$	(1,547	)	$	213,558



	December 31, 2017
(In thousands)	Amortized Cost		Gross unrealized gains		Gross unrealized losses			Fair Value
Short-term AFS securities
Corporate debt securities	$	150,334	$	—	$	(227	)	$	150,107
U.S. Treasury securities	70,985		—		(34		)	70,951
U.S. governmental agency securities	45,819		—		(179		)	45,640
Certificates of deposit	9,300		—		—			9,300
Commercial paper	32,591		—		—			32,591
Total short-term AFS securities	$	309,029	$	—	$	(440	)	$	308,589
Long-term AFS securities
Corporate debt securities	$	92,687	$	—	$	(683	)	92,004
U.S. Treasury securities	53,031		—		(403		)	52,628
U.S. governmental agency securities	97,798		—		(1,019		)	96,779
Total long-term AFS securities	$	243,516	$	—	$	(2,105	)	$	241,411

The following tables present the AFS securities as of December 30, 2018, and December 31, 2017 that were in an unrealized loss position, aggregated by investment category and the length of time that individual securities have been in a continuous loss position:



	December 30, 2018
	Less than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross unrealized losses			Fair Value		Gross unrealized losses			Fair Value		Gross unrealized losses
Short-term AFS securities
Corporate debt securities	$	76,886	$	(115	)	$	61,459	$	(349	)	$	138,345	$	(464	)
U.S. Treasury securities	70,830		(31		)	28,207		(201		)	99,037		(232		)
U.S. governmental agency securities	11,664		(4		)	80,311		(650		)	91,975		(654		)
Certificates of deposit	$	1,599	$	—		$	—	$	—		$	1,599	$	—
Total short-term AFS securities	$	160,979	$	(150	)	$	169,977	$	(1,200	)	$	330,956	$	(1,350	)
Long-term AFS securities
Corporate debt securities	$	81,655	$	(570	)	$	27,265	$	(462	)	$	108,920	$	(1,032	)
U.S. Treasury securities	20,479		(29		)	23,762		(318		)	44,241		(347		)
U.S. governmental agency securities	21,579		(36		)	11,868		(132		)	33,447		(168		)
Total long-term AFS securities	$	123,713	$	(635	)	$	62,895	$	(912	)	$	186,608	$	(1,547	)



	December 31, 2017
	Less than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross unrealized losses			Fair Value		Gross unrealized losses			Fair Value		Gross unrealized losses
Short-term AFS securities
Corporate debt securities	$	140,111	$	(199	)	$	9,996	$	(28	)	$	150,107	$	(227	)
U.S. Treasury securities	70,951		(34		)	—		—			70,951		(34		)
U.S. governmental agency securities	19,770		(50		)	25,870		(129		)	45,640		(179		)
Total short-term AFS securities	$	230,832	$	(283	)	$	35,866	$	(157	)	$	266,698	$	(440	)
Long-term AFS securities
Corporate debt securities	$	81,118	$	(579	)	$	10,886	$	(104	)	$	92,004	$	(683	)
U.S. Treasury securities	52,628		(403		)	—		—			52,628		(403		)
U.S. governmental agency securities	23,998		(125		)	72,781		(894		)	96,779		(1,019		)
Total long-term AFS securities	$	157,744	$	(1,107	)	$	83,667	$	(998	)	$	241,411	$	(2,105	)

We periodically review our AFS securities for OTTI. See Note 2 for factors we consider when assessing AFS securities for OTTI. As of December 30, 2018, and December 31, 2017, we did not intend to sell and it was not likely that we would be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. Unrealized losses related to these investments are primarily due to interest rate fluctuations as opposed to changes in credit quality. Therefore, as of December 30, 2018 and December 31, 2017, we have recognized no OTTI loss.

Marketable debt securities

As of December 30, 2018, and December 31, 2017, our short-term and long-term marketable securities had remaining maturities of less than 1 month to 12 months and 13 months to 34 months, respectively. See Note 9 for additional information regarding the fair value hierarchy of our marketable securities.

Letters of credit

We issued letters of credit totaling $48.8 million as of December 30, 2018, to secure commitments under certain sub-lease agreements associated with the rental of floors in our headquarters building. The letters of credit will expire by 2020, and are collateralized by marketable securities, with a fair value of $54.2 million, held in our investment portfolios. No amounts were outstanding on these letters of credit as of December 30, 2018. See Note 19 for additional information regarding the securities commitment.