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Stock-Based Compensation - Schedule of Stock Option Plan (Parenthetical) (Details) - shares
Jan. 31, 2019
Jan. 31, 2018
Jan. 31, 2017
Jan. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]        
Exercisable 264,244 394,455 482,255 374,377