Intangibles and Goodwill - Goodwill Rollforward (Details) - USD ($)	9 Months Ended	12 Months Ended
	Apr. 30, 2017	Jul. 31, 2016
Changes in Goodwill
Balance at the beginning of the period	$ 280,318,000	$ 241,951,000
Acquisitions	29,167,000	44,398,000
Foreign currency translation	(1,316,000)	(6,031,000)
Balance at the end of the period	308,169,000	280,318,000
Endoscopy
Changes in Goodwill
Balance at the beginning of the period	121,015,000	87,007,000
Acquisitions	7,178,000	40,047,000
Foreign currency translation	(1,113,000)	(6,039,000)
Balance at the end of the period	127,080,000	121,015,000
Water Purification and Filtration
Changes in Goodwill
Balance at the beginning of the period	58,880,000	58,872,000
Foreign currency translation	(203,000)	8,000
Balance at the end of the period	58,677,000	58,880,000
Healthcare Disposables
Changes in Goodwill
Balance at the beginning of the period	92,290,000	87,939,000
Acquisitions	21,989,000	4,351,000
Balance at the end of the period	114,279,000	92,290,000
Dialysis
Changes in Goodwill
Balance at the beginning of the period	8,133,000	8,133,000
Balance at the end of the period	$ 8,133,000	$ 8,133,000