Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Stock Option Activity, Number of shares
Outstanding at July 31, 2017, Number of shares outstanding (in shares)	122,500
Granted (in shares)	0
Exercised (in shares)	(52,500)
Outstanding at July 31, 2018, Number of shares outstanding (in shares)	70,000
Stock Option Activity, Weighted Average Exercise Price
Outstanding at July 31, 2017, Weighted Average Exercise Price (in dollars per share)	$ 29.36
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	17.04
Outstanding at July 31, 2018, Weighted Average Exercise Price (in dollars per share)	$ 38.60
Stock Option Activity, Additional Disclosures
Exercisable at July 31, 2018, Number of shares (in shares)	65,000
Exercisable at July 31, 2018, Weighted Average Exercise Price (in dollars per share)	$ 37.31
Outstanding at July 31, 2018, Weighted Average Contractual Life Remaining (Years)	11 months 12 days
Exercisable at July 31, 2018, Weighted Average Contractual Life Remaining (Years)	10 months 10 days
Outstanding at July 31, 2018, Aggregate Intrinsic Value	$ 3,788
Exercisable at July 31, 2018, Aggregate Intrinsic Value	3,601
Stock options
Stock Option Activity, Additional Disclosures
Outstanding at July 31, 2018, Aggregate Intrinsic Value	$ 3,788	$ 5,493	$ 4,605