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Net Income per Common Share - Additional Information (Detail) - $ / shares
12 Months Ended
Jan. 31, 2020
Jan. 31, 2019
Jan. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Anti-dilutive common shares 406,250 281,875 906,294
Anti-dilutive common shares exercise price, minimum $ 28.47 $ 35.85 $ 25.60
Anti-dilutive common shares exercise price, maximum $ 46.42 $ 46.42 $ 46.02
Performance Stock Units (PSUs)      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Anti-dilutive common shares 555,362 1,175,655