Earnings Per Common Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Earnings Per Share Disclosure [Line Items]
Weighted-average common shares outstanding for basic earnings per share	52,474,801	53,377,440	52,442,373	53,355,757
Unvested restricted stock and restricted stock units	86,321	81,091	110,968	88,973
Weighted-average common shares outstanding for diluted earnings per share	52,561,122	53,458,531	52,553,341	53,444,730