Goodwill (Detail) - USD ($)
$ in Thousands
Apr. 30, 2017
Jul. 31, 2016
Goodwill [Line Items]    
Goodwill $ 43,850 $ 43,850
Credence    
Goodwill [Line Items]    
Goodwill 28,662 28,662
Acquisition with Step Tech Inc. (June 10, 2003)    
Goodwill [Line Items]    
Goodwill 14,368 14,368
Titan Semiconductor Tool LLC    
Goodwill [Line Items]    
Goodwill $ 820 $ 820