Intangible Assets (Parenthetical) (Detail)	6 Months Ended	12 Months Ended
	Jan. 31, 2017	Jul. 31, 2016
Electronic chemicals-related contracts | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	5 years	5 years
Electronic chemicals-related contracts | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	8 years	8 years
Electronic chemicals-related trademarks and patents | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	10 years	10 years
Electronic chemicals-related trademarks and patents | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	15 years	15 years
Electronic chemicals-value of product qualifications | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	5 years	5 years
Electronic chemicals-value of product qualifications | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	15 years	15 years
Other chemicals-customer relationships
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	15 years	15 years
Other chemicals-other related contracts
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	5 years	5 years
Electronic chemicals - Tolling/License Agreements | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	1 year	1 year
Electronic chemicals - Tolling/License Agreements | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of intangible assets	3 years	3 years