XML 66 R53.htm IDEA: XBRL DOCUMENT v3.8.0.1
Derivative Instruments (Detail) - Forward Contracts - USD ($)
$ in Millions
3 Months Ended
Apr. 30, 2018
Jan. 31, 2018
Designated as Hedging Instrument    
Derivative [Line Items]    
Derivative, notional amount $ 639 $ 549
Designated as Hedging Instrument | Maximum    
Derivative [Line Items]    
Derivative, remaining maturity 36 months  
Not Designated as Hedging Instrument    
Derivative [Line Items]    
Derivative, notional amount $ 135 $ 75