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Intangible Assets - Additional Information (Detail) - USD ($)
12 Months Ended
Jan. 31, 2017
Jan. 31, 2016
Jan. 31, 2015
Impairment of Intangible Assets (Excluding Goodwill) [Abstract]      
Impairments of intangible assets $ 0 $ 0 $ 0
Amortization expense $ 700,000 $ 500,000 $ 700,000