Short-Term Investments (Tables)

9 Months Ended

Oct. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of Short-Term Investments

At October 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	$	3,500	$	5	$	—		$	3,505
Asset-backed securities	84,092		262		(6		)	84,348
Commercial paper	24,604		4		(2		)	24,606
Corporate notes and bonds	218,314		1,437		(26		)	219,725
Foreign government bonds	1,500		—		—			1,500
U.S. agency obligations	3,000		—		—			3,000
U.S. treasury securities	265,123		616		(16		)	265,723
Total available-for-sale securities	$	600,133	$	2,324	$	(50	)	$	602,407

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

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, 2019		January 31, 2019
Due in one year or less	$	351,301	$	377,858
Due in greater than one year	251,106		161,332
Total	$	602,407	$	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 a gross unrealized loss position for more than 12 months, aggregated by investment category as of October 31, 2019 (in thousands):

	Fair value		Gross unrealized losses
Asset-backed securities	$	9,545	$	(6	)
Commercial paper	10,561		(2		)
Corporate notes and bonds	27,851		(26		)
U.S. treasury securities	33,093		(16		)

The following table shows the fair values of these available-for-sale securities, some of which have been in a gross unrealized loss position for more than 12 months, aggregated by investment category as of January 31, 2019 (in thousands):

	Fair value		Gross 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		)