Short-Term Investments

3 Months Ended

Apr. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

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

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		)

We have not recorded an allowance for credit losses, as we believe any such losses would be immaterial based on the the high credit quality of our investments. We intend to hold our securities to maturity and it is unlikely that they would be sold before their cost bases are recovered.