Description of Business and Summary of Significant Accounting Policies - Summary of Weighted-Average Number of Shares used in Calculation of Basic and Diluted Earnings Per Share (Detail) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted-average number of shares	20,876	20,717	20,565
Stock options	9		5
Diluted weighted-average number of shares	22,315	22,060	22,482
Non Vested Restricted Stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Non-vested restricted common stock			499
Class B Common Stock [Member] | Non Vested Restricted Stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Non-vested restricted common stock	1,430	1,343	1,413