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Revenue Recognition - Narrative (Details) - USD ($)
$ in Thousands
Apr. 30, 2020
Jul. 31, 2019
Aug. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Retained earnings $ 553,917 $ 539,097  
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Retained earnings     $ 865