Fair Value Measurements - Recurring Basis (Details) - USD ($)	3 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jun. 30, 2014	Nov. 05, 2013
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis
Increase (decrease) in contingent guaranteed obligation	$ (283,000)	$ 9,000	$ 9,000	$ (136,000)	$ 20,000	$ 21,000	$ (592,000)
Jet Prep Ltd. | Contingent Consideration
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis
Increase (decrease) in contingent guaranteed obligation				(148,000)	5,000	4,000	(612,000)
Cantel Medical (UK) | Contingent guaranteed obligation
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis
Increase (decrease) in contingent guaranteed obligation	(283,000)	$ 9,000	$ 9,000	$ 12,000	$ 15,000	$ 17,000	$ 20,000
Level 3 | Recurring basis | Jet Prep Ltd.
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis
Assumed contingent obligation	1,138,000								$ 1,720,000
Level 3 | Recurring basis | Cantel Medical (UK)
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis
Contingent guaranteed obligation								$ 1,414,000
Increase (decrease) in contingent guaranteed obligation	$ 283,000