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Property and Equipment, Net (Narrative) (Detail) - USD ($)
$ in Millions
12 Months Ended
Jan. 31, 2019
Jan. 31, 2018
Jan. 31, 2017
Property, Plant and Equipment [Abstract]      
Depreciation expense $ 147 $ 115 $ 92
Interest costs capitalized to property and equipment $ 11 $ 8 $ 3