Stock-Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Oct. 31, 2019 USD ($) $ / shares shares
Number of shares
Outstanding, beginning balance (in shares) | shares	40,000
Exercised (in shares) | shares	(25,000)
Outstanding, ending balance (in shares) | shares	15,000
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 43.70
Exercised (in dollars per share) | $ / shares	36.70
Outstanding, ending balance (in dollars per share) | $ / shares	$ 55.36
Stock Option Activity, Additional Disclosures
Options outstanding, weighted average contractual life remaining	11 months 12 days
Options outstanding, aggregate intrinsic value | $	$ 263
Options exercisable, number of options (in shares) | shares	15,000
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 55.36
Options exercisable, weighted average contractual life remaining	11 months 12 days
Options exercisable, aggregate intrinsic value | $	$ 263