Stock-Based Compensation - Employee Stock Purchase Plan Activity (Details) - Employee Stock Purchase Plan - $ / shares	Jan. 31, 2019	Jul. 31, 2018
Stock-Based Compensation
Shares issued (in shares)	209,985	240,807
Fair market value at purchase date (in dollars per share)	$ 10.15	$ 8.67

Number of shares issued during the period as a result of an employee stock purchase plan.

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Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration