Fair Value Measurements - Level 3 Liabilities (Details) - USD ($)	3 Months Ended					12 Months Ended
	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2016
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	$ 1,579,000	$ 1,855,000	$ 1,918,000	$ 2,050,000	$ 2,777,000	$ 2,777,000
Total net unrealized (gains) losses included in general and administrative expense in earnings	9,000	(136,000)	20,000	21,000	(592,000)
Settlements	(70,000)	(196,000)	(95,000)	(100,000)	(120,000)
Foreign currency translation	(31,000)	56,000	12,000	(53,000)	(15,000)
Ending balance	1,487,000	1,579,000	1,855,000	1,918,000	2,050,000	1,579,000
Impairment of long-lived assets, including goodwill and intangibles with indefinite lives						0
Contingent Consideration | Jet Prep Ltd.
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance		148,000	143,000	139,000	751,000	751,000
Total net unrealized (gains) losses included in general and administrative expense in earnings		(148,000)	5,000	4,000	(612,000)
Ending balance			148,000	143,000	139,000
Assumed contingent liability | Jet Prep Ltd.
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	1,138,000	1,138,000	1,138,000	1,138,000	1,138,000	1,138,000
Ending balance	1,138,000	1,138,000	1,138,000	1,138,000	1,138,000	1,138,000
Contingent guaranteed obligation | Cantel Medical (UK) - PuriCore International Limited
Reconciliation of liability measured and recorded at fair value on a recurring basis using Level 3
Beginning balance	441,000	569,000	637,000	773,000	888,000	888,000
Total net unrealized (gains) losses included in general and administrative expense in earnings	9,000	12,000	15,000	17,000	20,000
Settlements	(70,000)	(196,000)	(95,000)	(100,000)	(120,000)
Foreign currency translation	(31,000)	56,000	12,000	(53,000)	(15,000)
Ending balance	$ 349,000	$ 441,000	$ 569,000	$ 637,000	$ 773,000	$ 441,000