Deferred Costs - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Deferred Costs [Abstract]
Deferred costs	$ 42,072,000	$ 35,585,000
Amortization of deferred costs	21,000,000	21,000,000	$ 18,000,000
Impairment losses recorded in relation to the costs capitalized	$ 0	$ 0	$ 0