Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jan. 31, 2015	Jul. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Net Amount	3,829
ECT and Multitest Acquisition and Credence Merger
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	32,600	32,600
Accumulated Amortization	(28,771)	(27,735)
Net Amount	3,829	4,865
ECT and Multitest Acquisition and Credence Merger | Developed Technology Rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	29,400	29,400
Accumulated Amortization	(26,439)	(25,880)
Net Amount	2,961	3,520
ECT and Multitest Acquisition and Credence Merger | Developed Technology Rights | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	6 years	6 years
ECT and Multitest Acquisition and Credence Merger | Developed Technology Rights | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	10 years	10 years
ECT and Multitest Acquisition and Credence Merger | Customer relationships- ECT, Multitest, Atg-Lm
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	2 years	2 years
Gross Carrying Amount	1,300	1,300
Accumulated Amortization	(839)	(498)
Net Amount	461	802
ECT and Multitest Acquisition and Credence Merger | Maintenance Agreements - ASL & Diamond
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	7 years	7 years
Gross Carrying Amount	1,900	1,900
Accumulated Amortization	(1,493)	(1,357)
Net Amount	407	543