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Property and Equipment, Net (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jul. 31, 2019
Jul. 31, 2018
Jul. 31, 2019
Jul. 31, 2018
Property, Plant and Equipment [Abstract]        
Depreciation expense $ 47 $ 36 $ 88 $ 69
Interest costs capitalized $ 2 $ 2 $ 6 $ 4