Financial Instruments (Tables)

3 Months Ended

Apr. 30, 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 April 30, 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 April 30, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cash Equivalents		Marketable Securities		Restricted Cash
Level 2
U.S. government notes	$	130,516	$	63	$	(6	)	$	130,573	$	28,813	$	101,760		—
U.S. government agencies		31,969		21		(1	)		31,989		—		31,989		—
Corporate debt securities		184,677		752		(27	)		185,402		—		185,402		—
Foreign government bonds		1,743		5		—			1,748		—		1,748		—
Money market accounts		—		—		—			—		—		—		6,427
Total	$	348,905	$	841	$	(34	)	$	349,712	$	28,813	$	320,899	$	6,427

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 April 30, 2016
	Amortized Cost		Fair Value
Due within one year	$	64,414	$	64,456
Due in one to five years		255,678		256,443
Total	$	320,092	$	320,899

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 April 30, 2016,  aggregated by investment category (in thousands):

	Less than 12 months
	Fair Value		Unrealized Loss
U.S. government notes	$	28,883	$	(6	)
U.S. government agencies		2,995		(1	)
Corporate debt securities		25,213		(27	)
Total	$	57,091	$	(34	)