Deferred Costs - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred costs	$ 35,585,000	$ 30,869,000
Amortization of deferred costs	20,521,000	18,378,000	$ 16,647,000
Impairment losses recorded in relation to the costs capitalized	0	0	0
Sales and marketing
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Amortization of deferred costs	$ 20,500,000	$ 18,400,000	$ 16,600,000