Earnings Per Share - Summary of Weighted-Average Number of Shares used in Calculation of Basic and Diluted Earnings Per Share (Details) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Weighted-average number of shares used in the calculation of basic and diluted earnings per share
Basic weighted-average number of shares	21,572	20,829	21,305	20,818
Effect of dilutive securities:
Stock options	132		109
Non-vested restricted Class B common stock	1,039	1,260	1,413	1,269
Diluted weighted-average number of shares	22,743	22,089	22,827	22,087