Short-Term Investments (Tables)

12 Months Ended

Jan. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of Short-Term Investments

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

At January 31, 2019, 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	$	6,001	$	10	$	(1	)	$	6,010
Asset-backed securities	78,682		13		(300		)	78,395
Commercial paper	9,118		1		(2		)	9,117
Corporate notes and bonds	185,409		178		(457		)	185,130
Foreign government bonds	1,502		—		(11		)	1,491
U.S. agency obligations	15,912		2		(2		)	15,912
U.S. treasury securities	243,119		78		(62		)	243,135
Total available-for-sale securities	$	539,743	$	282	$	(835	)	$	539,190

Summary of Estimated Fair Value of Short-Term Investments, Designated as Available-for-Sale and Classified by Contractual Maturity

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):

	January 31,
	2020		2019
Due in one year or less	$	247,592	$	377,858
Due in greater than one year	362,423		161,332
Total	$	610,015	$	539,190

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 January 31, 2020 (in thousands):

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

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, 2019 (in thousands):

	Fair value		Unrealized losses
Certificates of deposits	$	999	$	(1	)
Asset-backed securities	69,131		(300		)
Commercial paper	7,155		(2		)
Corporate notes and bonds	121,006		(457		)
Foreign government bonds	1,490		(11		)
U.S. agency obligations	14,928		(2		)
U.S. treasury securities	130,785		(62		)