Financial Instruments (Tables)

6 Months Ended

Jul. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Summary of Cash Equivalents, Marketable Securities and Restricted Cash by Significant Investment Categories

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

	As of 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	$	45,614	$	—
Level 2
Certificate of deposits	7,132		—		—		7,132		—		7,132
Total	$	52,746	$	—	$	—	$	52,746	$	45,614	$	7,132

	As of July 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash Equivalents		Marketable Securities		Restricted Cash
Level 1
Money market accounts	$	—	$	—	$	—		$	—	$	—	$	—	$	12,732
Level 2
U.S. government treasury notes	135,581		181		(3		)	135,759		18,546		117,213		—
U.S. government agencies	47,655		41		(6		)	47,690		4,001		43,689		—
Corporate debt securities	200,093		1,146		(15		)	201,224		401		200,823		—
Foreign government bonds	2,624		7		—			2,631		—		2,631		—
Total	$	385,953	$	1,375	$	(24	)	$	387,304	$	22,948	$	364,356	$	12,732

Schedule of Amortized Cost and Estimated Fair Value of Marketable Securities by Contractual Maturity

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

	As of July 31, 2016
	Amortized Cost		Fair Value
Due within one year	$	78,421	$	78,470
Due in one to five years	284,585		285,886
Total	$	363,006	$	364,356

Schedule of Gross Unrealized Losses and Fair Values for Investments that were in Continuous Unrealized Loss Position for Less Than 12 Months, Aggregated by Investments Category

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 July 31, 2016, aggregated by investment category (in thousands):

	Less than 12 months
	Fair Value		Unrealized Loss
U.S. government notes	$	2,002	$	(3	)
U.S. government agencies	6,492		(6		)
Corporate debt securities	13,689		(15		)
Total	$	22,183	$	(24	)