Deferred Costs - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020	Jan. 31, 2021
Deferred Costs [Abstract]
Deferred costs	$ 37,335,000		$ 37,335,000		$ 42,072,000
Amortization of deferred costs	6,000,000	$ 5,000,000	13,000,000	$ 10,000,000
Impairment losses recorded in relation to the costs capitalized	$ 0	$ 0	$ 0	$ 0