Schedule of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 110,276	$ 80,124	$ 230,562	$ 160,209
Income (loss) from operations	11,285	1,210	31,984	1,516
Depreciation and amortization expense			3,280	3,106
Continuing Operations
Segment Reporting Information [Line Items]
Depreciation and amortization expense	1,660	1,560	3,280	3,106
Semiconductor Test Solutions
Segment Reporting Information [Line Items]
Net sales	91,841	64,270	191,897	129,083
Income (loss) from operations	12,314	1,464	31,584	1,147
Semiconductor Test Solutions | Continuing Operations
Segment Reporting Information [Line Items]
Depreciation and amortization expense	1,386	1,350	2,729	2,700
Electronic Manufacturing Solutions
Segment Reporting Information [Line Items]
Net sales	18,435	15,854	38,665	31,126
Income (loss) from operations	(1,029)	(254)	400	369
Electronic Manufacturing Solutions | Continuing Operations
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 274	$ 210	$ 551	$ 406