Schedule of Difference Between Basic and Diluted EPS as Result of Restricted Stock Units and Unvested Restricted Stock (Detail) - shares	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Earnings Per Share [Abstract]
Weighted-average shares outstanding for basic earnings per share	52,806,981	52,694,680	52,766,739	52,653,303
Unvested restricted stock units	60,706	166,460	116,906	186,449
Weighted-average shares outstanding assuming dilution	52,867,687	52,861,140	52,883,645	52,839,752