Restructuring and Realignment Events - Accrued Liability Associated with Restructuring and Other Related Charges (Detail) $ in Thousands	6 Months Ended
	Jan. 31, 2017 USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued liability, Beginning balance	$ 757
Payments	(221)
Adjustment	(21)
Accrued liability, Ending balance	515
Employee costs
Restructuring Cost And Reserve [Line Items]
Accrued liability, Beginning balance	721
Payments	(196)
Adjustment	(27)
Accrued liability, Ending balance	498
Decommissioning and Environmental
Restructuring Cost And Reserve [Line Items]
Accrued liability, Beginning balance	36
Payments	(19)
Accrued liability, Ending balance	17
Other
Restructuring Cost And Reserve [Line Items]
Payments	(6)
Adjustment	$ 6