Employee Benefits and Stock-based Compensation - Classification of Stock-based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Stock-based compensation:
Total stock-based compensation	$ 70,134	$ 66,871	$ 60,812
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	1,328	1,184	1,261
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	42,903	41,842	37,432
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 25,903	$ 23,845	$ 22,119