Fair Value Measurements - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Oct. 31, 2018	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 14,951	$ 15,460
Total Liabilities	505	3
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	14,060	14,383
Total Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	14,060	14,383
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	891	1,077
Total Liabilities	505	3
Fair Value, Inputs, Level 2 [Member] | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts	891	1,077
Fair Value, Inputs, Level 2 [Member] | Other current liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts	$ 505	$ 3