Short-Term Investments - Schedule of Short-Term Investments (Detail) - USD ($) $ in Thousands	Oct. 31, 2021	Jan. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 1,202,979	$ 929,273
Gross unrealized gains	1,133	3,879
Gross unrealized losses	(2,571)	(30)
Estimated fair value	1,201,541	933,122
Certificates of deposits
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	16,750	17,350
Gross unrealized gains	10	15
Gross unrealized losses	0	(1)
Estimated fair value	16,760	17,364
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	190,558	125,833
Gross unrealized gains	152	745
Gross unrealized losses	(458)	(2)
Estimated fair value	190,252	126,576
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	47,375	57,390
Gross unrealized gains	8	8
Gross unrealized losses	0	(2)
Estimated fair value	47,383	57,396
Corporate notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	642,377	428,710
Gross unrealized gains	809	2,360
Gross unrealized losses	(1,609)	(23)
Estimated fair value	641,577	431,047
Foreign government bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	26,625	31,855
Gross unrealized gains	23	45
Gross unrealized losses	(57)	(2)
Estimated fair value	26,591	31,898
U.S. agency obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	27,974	52,756
Gross unrealized gains	14	119
Gross unrealized losses	(50)	0
Estimated fair value	27,938	52,875
U.S. treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	251,320	215,379
Gross unrealized gains	117	587
Gross unrealized losses	(397)	0
Estimated fair value	$ 251,040	$ 215,966