Derivatives - Schedule of Outstanding Foreign Currency Derivative Contracts Related Primarily to Intercompany Receivables and Payables (Detail) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	Oct. 31, 2018	Jan. 31, 2018
Derivative [Line Items]
Fair value of foreign currency derivative contracts	$ (3)	$ 12
Foreign currency derivative contracts
Derivative [Line Items]
Notional amount of foreign currency derivative contracts	$ 1,588	$ 1,871