Deferred Costs - Additional Information (Detail) - USD ($)	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2020
Deferred Costs [Abstract]
Deferred costs	$ 34,176,000		$ 35,585,000
Amortization of deferred costs	4,751,000	$ 4,849,000
Impairment losses recorded in relation to the costs capitalized	$ 0	$ 0