Short-Term Investments (Tables)

3 Months Ended

Apr. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of Short-Term Investments

At April 30, 2020, short-term investments consisted of the following (in thousands):

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
Available-for-sale securities:
Certificates of deposits	$	11,600	$	38	$	(55	)	$	11,583
Asset-backed securities	104,406		476		(162		)	104,720
Commercial paper	37,028		47		(24		)	37,051
Corporate notes and bonds	270,889		2,283		(410		)	272,762
Foreign government bonds	4,803		32		(35		)	4,800
U.S. agency obligations	4,999		3		—			5,002
U.S. treasury securities	222,201		2,080		—			224,281
Total available-for-sale securities	$	655,926	$	4,959	$	(686	)	$	660,199

At January 31, 2020, short-term investments consisted of the following (in thousands):

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
Available-for-sale securities:
Certificates of deposits	$	3,500	$	3	$	—		$	3,503
Asset-backed securities	100,419		396		(1		)	100,814
Commercial paper	19,965		5		(1		)	19,969
Corporate notes and bonds	234,664		1,552		(2		)	236,214
Foreign government bonds	3,397		10		—			3,407
U.S. treasury securities	245,509		599		—			246,108
Total available-for-sale securities	$	607,454	$	2,565	$	(4	)	$	610,015

The following table summarizes the estimated fair value of our short-term investments, designated as available-for-sale and classified by the contractual maturity date of the securities as of the dates shown (in thousands):

	April 30, 2020		January 31, 2020
Due in one year or less	$	282,638	$	247,592
Due in greater than one year	377,561		362,423
Total	$	660,199	$	610,015

Schedule of Fair Values and Gross Unrealized Loss Position of Available-for-Sale Securities Aggregated by Investment Category

The following table shows the fair values of these available-for-sale securities, some of which have been in an unrealized loss position for more than 12 months, aggregated by investment category as of April 30, 2020 (in thousands):

	Fair value		Gross unrealized losses
Certificates of deposits	$	7,945	$	(55	)
Asset-backed securities	19,765		(162		)
Commercial paper	10,609		(24		)
Corporate notes and bonds	56,364		(410		)
Foreign government bonds	3,545		(35		)

The following table shows the fair values of these available-for-sale securities, some of which have been in an unrealized loss position for more than 12 months, aggregated by investment category as of January 31, 2020 (in thousands):

	Fair value		Gross unrealized losses
Asset-backed securities	$	2,623	$	(1	)
Commercial paper	5,589		(1		)
Corporate notes and bonds	9,105		(2		)