Description of Business and Summary of Significant Accounting Policies (Details) - shares shares in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Summary of weighted-average number of shares used in calculation of basic and diluted earnings per share
Basic weighted-average number of shares	25,293	24,655	23,182
Effect of dilutive securities:
Stock options		9	44
Non-vested restricted Class B common stock	15	54	83
Diluted weighted-average number of shares	25,308	24,718	23,309