Summary of Business Operations and Significant Accounting Policies - Additional Information (Detail)		3 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($)	Jul. 31, 2017 USD ($)	Apr. 30, 2017 USD ($)	Jul. 31, 2017 USD ($) Segment	Jul. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Total unbilled receivables		$ 4,200,000		$ 4,200,000	$ 4,000,000
Long-term portion of unbilled receivables		0		0	0
Total deferred revenue		6,800,000		6,800,000	7,200,000
Long-term portion of deferred revenue		2,000,000		2,000,000	1,800,000
Depreciation and amortization of property, plant, and equipment				17,400,000	15,000,000	$ 14,100,000
Interest costs capitalized				0	0	0
Asset impairment charges		1,000,000		84,510,000	0	0
Goodwill impairment charges				71,600,000
Amortization expense of capitalized software development costs				7,400,000	8,400,000	8,900,000
Foreign currency translation adjustment, net of tax				1,375,000	(2,293,000)	(12,564,000)
Foreign exchange gains (losses)				$ (100,000)	(2,700,000)	(400,000)
Reportable segment | Segment				3
Increase to cost of sales				$ 282,096,000	275,632,000	302,974,000
Increase to general and administrative expenses				43,064,000	60,826,000	57,291,000
Selling and Marketing
Significant Accounting Policies [Line Items]
Advertising expenses				100,000	300,000	400,000
Computer Software, Intangible Asset
Significant Accounting Policies [Line Items]
Amortization expense of capitalized software development costs				500,000	200,000	$ 200,000
Unamortized capitalized software costs		500,000		$ 500,000	$ 500,000
Minimum
Significant Accounting Policies [Line Items]
Standard product warranty term				12 months
Intangible assets, estimated useful lives				1 year
Minimum | Computer Software, Intangible Asset
Significant Accounting Policies [Line Items]
Intangible assets, estimated useful lives				3 years
Maximum
Significant Accounting Policies [Line Items]
Standard product warranty term				60 months
Intangible assets, estimated useful lives				14 years
Maximum | Computer Software, Intangible Asset
Significant Accounting Policies [Line Items]
Intangible assets, estimated useful lives				5 years
Ultrasound
Significant Accounting Policies [Line Items]
Asset impairment charges				$ 200,000
Goodwill impairment charges	$ 0		$ 55,200,000
ASU 2017-04 | Ultrasound
Significant Accounting Policies [Line Items]
Goodwill impairment charges			55,200,000
ASU 2017-04 | Oncura
Significant Accounting Policies [Line Items]
Goodwill impairment charges			$ 6,600,000
Demonstration Inventory
Significant Accounting Policies [Line Items]
Inventory estimated remaining useful life				3 years
Prior to fiscal 2016 | Demonstration Inventory
Significant Accounting Policies [Line Items]
Inventory amortized period						4 years
Out-of-period adjustments
Significant Accounting Policies [Line Items]
Out of period adjustment		2,200,000
Increase to cost of sales		1,100,000
Increase to general and administrative expenses		$ 1,100,000