401(k) Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Total expense related defined benefit plan	$ 3,900,000	$ 3,300,000	$ 400,000
401(K) Plan
Defined Contribution Plan Disclosure [Line Items]
Employer maximum matching contribution amount per employee per year	2,000
RRSP | Canada
Defined Contribution Plan Disclosure [Line Items]
Employer maximum matching contribution amount per employee per year	$ 2,000