Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Stock Option Activity, Number of shares
Outstanding at beginning of period (in shares)	40,000	70,000	122,500
Exercised (in shares)	(25,000)	(30,000)	(52,500)
Outstanding at end of period (in shares)	15,000	40,000	70,000
Stock Option Activity, Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 43.70	$ 38.60	$ 29.36
Exercised (in dollars per share)	36.70	31.81	17.04
Outstanding at end of period (in dollars per share)	$ 55.36	$ 43.70	$ 38.60
Stock Option Activity, Additional Disclosures
Exercisable at end of period, Number of shares (in shares)	15,000
Exercisable at end of period, Weighted Average Exercise Price (in dollars per share)	$ 55.36
Outstanding at end of period, Weighted Average Contractual Life Remaining	2 months 12 days
Exercisable at end of period, Weighted Average Contractual Life Remaining	2 months 12 days
Outstanding at end of period, Aggregate Intrinsic Value	$ 0
Exercisable at end of period, Aggregate Intrinsic Value	$ 0