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Goodwill and Intangible Assets - Additional Information (Details) - USD ($)
3 Months Ended 6 Months Ended
Jul. 31, 2017
Jul. 31, 2016
Jul. 31, 2017
Jul. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]        
Goodwill acquired $ 0   $ 0  
Amortization of intangible assets   $ 900,000 $ 400,000 $ 2,400,000