Short-Term Investments

9 Months Ended

Oct. 31, 2020

Investments, Debt and Equity Securities [Abstract]

At October 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	$	15,600	$	13	$	(1)	$	15,612
Asset-backed securities	130,733		821		(10)		131,544
Commercial paper	58,602		35		(1)		58,636
Corporate notes and bonds	414,837		2,528		(184)		417,181
Foreign government bonds	32,011		33		(17)		32,027
U.S. agency obligations	52,751		71		—		52,822
U.S. treasury securities	247,505		843		(3)		248,345
Total available-for-sale securities	$	952,039	$	4,344	$	(216)	$	956,167

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):


	October 31, 2020		January 31, 2020
Due in one year or less	$	434,612	$	247,592
Due in greater than one year	521,555		362,423
Total	$	956,167	$	610,015

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


	Fair value		Gross unrealized losses
Certificates of deposits	$	2,999	$	(1)
Asset-backed securities	11,771		(10)
Commercial paper	13,329		(1)
Corporate notes and bonds	154,408		(184)
Foreign government bonds	24,293		(16)
U.S. treasury securities	21,984		(3)

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 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.