Summary of Business and Significant Accounting Policies - Schedule of Condensed Consolidated Balance Sheet (Detail) - USD ($)
$ in Thousands
Apr. 30, 2018
Jan. 31, 2018
Assets    
Accounts receivable $ 154,840 $ 224,668 [1],[2]
Unbilled accounts receivable 17,635 13,348 [1],[2]
Deferred costs, net 29,338 30,306 [1]
Deferred income taxes, noncurrent 2,189 2,222 [1]
Liabilities    
Deferred revenue 289,560 266,939 [1]
Deferred income taxes, noncurrent 9,737 10,949 [1]
Stockholders’ equity:    
Accumulated other comprehensive income 1,096 1,600 [1]
Retained earnings $ 433,675 389,365 [1]
As Reported [member] | Topic 606 [Member]    
Assets    
Accounts receivable [2]   233,731
Deferred income taxes, noncurrent   3,490
Liabilities    
Deferred revenue   275,446
Deferred income taxes, noncurrent   3,828
Stockholders’ equity:    
Accumulated other comprehensive income   1,404
Retained earnings   354,850
Adjustments [Member] | Topic 606 [Member]    
Assets    
Accounts receivable [2]   (9,063)
Unbilled accounts receivable [2]   13,348
Deferred costs, net   30,306
Deferred income taxes, noncurrent   (1,268)
Liabilities    
Deferred revenue   (8,507)
Deferred income taxes, noncurrent   7,121
Stockholders’ equity:    
Accumulated other comprehensive income   196
Retained earnings   $ 34,515
[1] See note 1 of the notes to the condensed consolidated financial statements for a summary of adjustments.
[2] Unbilled accounts receivable was previously included in Accounts receivable before the adoption of Topic 606.