Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Leases [Line Items]
Operating lease expense	$ 3	$ 2	$ 9	$ 5
Maximum
Leases [Line Items]
Operating leases, options to extend leases term	9 years		9 years
Finance leases, options to extend leases term	9 years		9 years