Fair Value of Financial Instruments (Details 2) $ in Thousands	Jul. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Less than 12 Months, Fair Value	$ 55,433
Less than 12, Months, Gross Unrealized Losses	(119)
12 Months or Greater, Fair Value	0
12 Months or Greater, Gross Unrealized Losses	0
Total, Fair Value	55,433
Total, Gross Unrealized Losses	(119)
U.S. Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Less than 12 Months, Fair Value	34,195
Less than 12, Months, Gross Unrealized Losses	(81)
12 Months or Greater, Fair Value	0
12 Months or Greater, Gross Unrealized Losses	0
Total, Fair Value	34,195
Total, Gross Unrealized Losses	(81)
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Less than 12 Months, Fair Value	21,238
Less than 12, Months, Gross Unrealized Losses	(38)
12 Months or Greater, Fair Value	0
12 Months or Greater, Gross Unrealized Losses	0
Total, Fair Value	21,238
Total, Gross Unrealized Losses	$ (38)