Nature of Business and Basis of Presentation - Additional Information (Detail) - Irish Operations [Member] - USD ($) $ in Millions |
Apr. 30, 2017 |
Jul. 31, 2016 |
|---|---|---|
| Nature Of Business And Basis Of Presentation [Line Items] | ||
| Undistributed earnings of foreign subsidiaries | $ 58.6 | |
| Deferred tax liability related to the foreign income | $ 15.1 | $ 14.7 |