Marketable Securities

The Company’s investments that have original maturities greater than 90 days have been classified as available-for-sale securities in accordance with U.S. GAAP. Marketable securities are categorized on the consolidated condensed balance sheet as short- and long-term marketable securities, as appropriate.

The following table is a summary of available-for-sale securities at December 29, 2018 (in thousands):



As of December 29, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value (Net Carrying Amount)
Corporate debt securities	$	212,338	$	142	$	(1,703	)	$	210,777
Non-US government securities	13,704		2		(84		)	13,622
Agency discount notes	459		—		(2		)	457
Total securities	$	226,501	$	144	$	(1,789	)	$	224,856

The Company typically invests in highly-rated securities with original maturities generally ranging from one to three years. The Company's specifically identified gross unrealized loss of $1.8 million related to securities with total amortized cost of approximately $185.0 million at December 29, 2018. Securities in a continuous unrealized loss position for more than 12 months as of December 29, 2018 had an aggregate amortized cost of $132.5 million and an aggregate unrealized loss of $1.4 million. The Company may sell certain of its marketable securities prior to their stated maturities for strategic reasons including, but not limited to, anticipated or actual changes in credit rating and duration management. When evaluating an investment for other-than-temporary impairment, the Company reviews factors including the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer, changes in market interest rates and whether it is more likely than not the Company will be required to sell the investment before recovery of the investment’s cost basis. As of December 29, 2018, the Company does not consider any of its investments to be other-than-temporarily impaired.

The following table is a summary of available-for-sale securities at March 31, 2018 (in thousands):

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As of March 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value (Net Carrying Amount)
Corporate debt securities	$	185,636	$	4	$	(2,318	)	$	183,322
Non-US government securities	14,730		—		(111		)	14,619
Certificates of deposit	500		—		—			500
Agency discount notes	459		—		(4		)	455
Total securities	$	201,325	$	4	$	(2,433	)	$	198,896

The Company’s specifically identified gross unrealized losses of $2.4 million related to securities with total amortized cost of approximately $198.2 million at March 31, 2018. There were no securities that have been in a continuous loss position for more than 12 months as of March 31, 2018. The Company may sell certain of its marketable securities prior to their stated maturities for strategic reasons including, but not limited to, anticipated or actual changes in credit rating and duration management. When evaluating an investment for other-than-temporary impairment, the Company reviews factors including the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer, changes in market interest rates and whether it is more likely than not the Company will be required to sell the investment before recovery of the investment’s cost basis. As of March 31, 2018, the Company did not consider any of its investments to be other-than-temporarily impaired.

The cost and estimated fair value of available-for-sale securities by contractual maturities were as follows (in thousands):

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	December 29, 2018				March 31, 2018
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Within 1 year	$	60,157	$	59,793	$	26,560	$	26,397
After 1 year	166,344		165,063		174,765		172,499
Total	$	226,501	$	224,856	$	201,325	$	198,896