Net Income per Share Attributable to Common Stockholders - Potential Common Share Equivalents Excluded where the Inclusion would be Anti-dilutive (Detail) - shares |
12 Months Ended | ||
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Jan. 31, 2019 |
Jan. 31, 2018 |
Jan. 31, 2017 |
|
Earnings Per Share [Abstract] | |||
Options and awards to purchase shares not included in the computation of diluted net income per share because their inclusion would be anti-dilutive | 3,054,322 | 833,691 | 2,040,238 |