Reportable Segments - Results (Details) - USD ($) $ in Thousands	3 Months Ended
Oct. 31, 2017	Oct. 31, 2016
Information as to operating segments
Net sales	$ 212,766	$ 187,725
Segment operating income	31,634	27,063
General corporate expenses	32,096	30,003
Operating Segment
Information as to operating segments
Segment operating income	40,833	35,690
Endoscopy
Information as to operating segments
Net sales	112,385	93,828
Endoscopy \| Operating Segment
Information as to operating segments
Segment operating income	19,684	17,561
Water Purification and Filtration
Information as to operating segments
Net sales	53,555	49,873
Water Purification and Filtration \| Operating Segment
Information as to operating segments
Segment operating income	10,150	8,920
Healthcare Disposables
Information as to operating segments
Net sales	38,892	36,799
Healthcare Disposables \| Operating Segment
Information as to operating segments
Segment operating income	8,900	7,396
Dialysis
Information as to operating segments
Net sales	7,934	7,225
Dialysis \| Operating Segment
Information as to operating segments
Segment operating income	2,099	1,813
General corporate \| Segment reconciling items
Information as to operating segments
General corporate expenses	$ 9,199	$ 8,627

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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The net result for the period of deducting operating expenses from operating revenues.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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