Property, Plant, and Equipment and Related Accumulated Depreciation and Amortization (Parenthetical) (Detail) $ in Millions	Jan. 31, 2017 USD ($)	Jul. 31, 2016 USD ($) Facility
Property Plant And Equipment [Abstract]
Estimated fair value of property, less cost to sell | $	$ 4.3	$ 4.3
Number of excess capacity manufacturing facilities | Facility		1