Acquisitions - DentaPure (Details)	Feb. 20, 2015 USD ($) project	Jul. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Jul. 31, 2014 USD ($)
Net Assets
Goodwill		$ 280,318,000	$ 241,951,000	$ 231,647,000
DentaPure
Acquisitions
Pre-acquisition annual revenues	$ 2,300,000
Total consideration for the transaction, excluding acquisition-related costs	9,980,000
Net Assets
Current assets	566,000
Property, plant and equipment	50,000
Current liabilities	(248,000)
Deferred income tax liabilities	(2,172,000)
Net assets acquired	$ 3,876,000
Amortizable intangible assets, useful life	10 years
Number of in-process research and development projects acquired | project	0
Goodwill	$ 6,104,000
Goodwill deductible for income tax purposes	0
DentaPure | Customer relationships
Net Assets
Amortizable intangible assets	$ 4,640,000
Amortizable intangible assets, useful life	10 years
DentaPure | Technology
Net Assets
Amortizable intangible assets	$ 780,000
Amortizable intangible assets, useful life	10 years
DentaPure | Brand names
Net Assets
Amortizable intangible assets	$ 260,000
Amortizable intangible assets, useful life	10 years