Summary of Estimated Fair Values of Separately Identifiable Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Jul. 31, 2016	Jan. 08, 2016	Jul. 31, 2015	Oct. 28, 2014	Sep. 20, 2013
Business Acquisition [Line Items]
Goodwill	$ 73,915		$ 57,450
PocketSonics
Business Acquisition [Line Items]
Cash					$ 500
Goodwill					6,900
Total assets acquired					18,900
Accounts payable and accrued expenses					(300)
Deferred taxes					(4,100)
Total liabilities assumed					(4,400)
Total purchase price					14,500
PocketSonics | In-process research and development
Business Acquisition [Line Items]
Intangible assets					$ 11,500
Pathfinder Therapeutics Inc
Business Acquisition [Line Items]
Inventory and receivables				$ 200
Goodwill				400
Intangible assets				1,100
Total assets acquired				1,700
Accounts payable and accrued expenses				(100)
Total liabilities assumed				(100)
Total purchase price				1,600
Pathfinder Therapeutics Inc | Developed technologies
Business Acquisition [Line Items]
Intangible assets				700
Pathfinder Therapeutics Inc | Customer relationships
Business Acquisition [Line Items]
Intangible assets				300
Pathfinder Therapeutics Inc | Trade names
Business Acquisition [Line Items]
Intangible assets				$ 100
Oncura
Business Acquisition [Line Items]
Cash		$ 400
Accounts receivable		300
Inventory		200
Other assets		400
Property, plant, and equipment		400
Goodwill		16,400
Intangible assets		4,100
Total assets acquired		22,200
Accounts payable and accrued expenses		(900)
Deferred revenue		(1,100)
Total liabilities assumed		(2,000)
Total purchase price		20,200
Oncura | Customer relationships
Business Acquisition [Line Items]
Intangible assets		3,100
Oncura | Trade names
Business Acquisition [Line Items]
Intangible assets		$ 1,000