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Share-Based Compensation - Summarized Plan Activity (Detail) - Employee Stock Purchase Plan [Member] - shares
12 Months Ended
Jan. 31, 2021
Jan. 31, 2020
Jan. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares Reserved, Beginning Balance 24,974 33,853 39,207
Shares Purchased (14,600) (8,879) (5,354)
Shares Reserved, Ending Balance 10,374 24,974 33,853