Financial Instruments (Tables)

12 Months Ended

Jan. 31, 2017

Fair Value, Assets Measured on Recurring Basis

The following tables summarize our cash equivalents, marketable securities and restricted cash by significant investment categories as of January 31, 2016 and 2017 (in thousands):



	January 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Cash Equivalents		Restricted Cash
Level 1
Money market funds	$	—	$	—	$	—	$	45,614	$	45,614	$	—
Level 2
Certificates of deposit	—		—		—		7,132		—		7,132
Total	$	—	$	—	$	—	$	52,746	$	45,614	$	7,132



	January 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash Equivalents		Marketable Securities		Restricted Cash
Level 1
Money market accounts	$	—	$	—	$	—		$	12,734	$	—	$	—	$	12,734
Level 2
U.S. government treasury notes	148,298		22		(289		)	148,031		13,226		134,805		—
U.S. government agencies	40,398		2		(159		)	40,241		—		40,241		—
Corporate debt securities	185,701		242		(379		)	185,564		—		185,564		—
Foreign government bonds	2,377		2		(3		)	2,376		—		2,376		—
Total	$	376,774	$	268	$	(830	)	$	388,946	$	13,226	$	362,986	$	12,734

Investments Classified by Contractual Maturity Date

The amortized cost and estimated fair value of our marketable securities are shown below by contractual maturity (in thousands):



	January 31, 2017
	Amortized Cost		Fair Value
Due within one year	$	103,213	$	103,238
Due in one to five years	260,335		259,748
Total	$	363,548	$	362,986

Schedule of Unrealized Loss on Investments

The following table presents gross unrealized losses and fair values for those investments that were in a continuous unrealized loss position for less than 12 months as of January 31, 2017, aggregated by investment category (in thousands):



	Less than 12 months
	Fair Value		Unrealized Loss
U.S. government treasury notes	$	82,228	$	(289	)
U.S government agencies	34,485		(159		)
Corporate debt securities	99,710		(379		)
Foreign government bonds	877		(3		)
Total	$	217,300	$	(830	)