Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Intangible Assets - Additional Information (Detail)

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Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jul. 31, 2018
Jul. 31, 2017
Jul. 31, 2018
Jul. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]        
Percentage of estimated fair value of reporting unit exceeded its carrying value, including goodwill 28.70%   28.70%  
Impairment charge $ 0      
Other long-lived assets 0      
Amortization of intangible assets $ 400,000 $ 600,000 $ 800,000 $ 1,200,000