Restructuring Charges - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended					12 Months Ended
	May 31, 2013 USD ($) Person	Jul. 31, 2016 USD ($)	Apr. 30, 2016 USD ($)	Jan. 31, 2016 USD ($)	Oct. 31, 2015 USD ($)	Jul. 31, 2014 USD ($) Employee	Jul. 31, 2016 USD ($) Employee		Jul. 31, 2015 USD ($)		Jul. 31, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							$ 9,641	[1],[2]	$ (354)	[1],[2]	$ 3,483
Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							6,000		(200)		1,700
Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							1,900		(100)		1,400
Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							1,700		(100)		400
Fiscal Year 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charge		$ 1,400	$ 1,800	$ 3,100	$ 3,300		$ 9,600
Involuntarily terminated employees | Employee							117
Fiscal Year 2016 Restructuring Plan | Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							$ 6,000
Fiscal Year 2016 Restructuring Plan | Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							1,900
Fiscal Year 2016 Restructuring Plan | Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring Charge							$ 1,700
Fiscal Year 2014 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charge									(300)		2,900
Fiscal Year 2014 Restructuring Plan | Ultrasonix
Restructuring Cost and Reserve [Line Items]
Restructuring Charge						$ 2,900
Involuntarily terminated employees | Employee						48
Fiscal Year 2014 Restructuring Plan | Ultrasonix | Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring Charge						$ 1,900
Fiscal Year 2014 Restructuring Plan | Ultrasonix | Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring Charge						500
Fiscal Year 2014 Restructuring Plan | Ultrasonix | Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring Charge						$ 500
Fiscal Year 2013 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charge	$ 4,100								$ (100)		$ (200)
Involuntarily terminated employees | Person	115

[1] Activity in fiscal year 2015 pertains to both the Fiscal Year 2014 Restructuring Plan and the 2013 Restructuring Plan. In fiscal year 2015, the restructuring adjustments of ($0.3) million and cash payments of ($2.4) million relate to the Fiscal Year 2014 Restructuring Plan, while restructuring adjustments of ($0.1) million and cash payments of ($0.5) million relate to the Fiscal Year 2013 Restructuring Plan.

[2] Activity in fiscal year 2016 pertains to the Fiscal Year 2016 Restructuring Plan, the Fiscal Year 2014 Restructuring Plan and the 2013 Restructuring Plan. In fiscal year 2016, there were restructuring charges of $9.6 million and cash payments of ($4.4) million related to the Fiscal Year 2016 Restructuring Plan, while there were cash payments of ($0.2) million and ($0.4) million related to the Fiscal Year 2014 Restructuring Plan and Fiscal Year 2013 Restructuring Plan, respectively.