Financial Instruments (Tables)

9 Months Ended

Oct. 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 October 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 October 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash Equivalents		Marketable Securities		Restricted Cash
Level 1
Money market accounts	$	—	$	—	$	—		$	—	$	—	$	—	$	12,734
Level 2
U.S. government treasury notes	143,532		67		(27		)	143,572		14,949		128,623		—
U.S. government agencies	41,161		13		(55		)	41,119		—		41,119		—
Corporate debt securities	192,944		581		(110		)	193,415		—		193,415		—
Foreign government bonds	2,625		3		—			2,628		—		2,628		—
Total	$	380,262	$	664	$	(192	)	$	380,734	$	14,949	$	365,785	$	12,734

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 October 31, 2016
	Amortized Cost		Fair Value
Due within one year	$	95,602	$	95,673
Due in one to five years	269,711		270,112
Total	$	365,313	$	365,785

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

	Less than 12 months
	Fair Value		Unrealized Loss
U.S. government treasury notes	$	35,647	$	(27	)
U.S. government agencies	28,274		(55		)
Corporate debt securities	47,483		(110		)
Total	$	111,404	$	(192	)