Other Income (Expense) - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jan. 31, 2016	Oct. 31, 2013	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Component Of Other Expense Income Nonoperating [Line Items]
Interest expense	$ 3.2		$ 3.2	$ 0.6
Foreign exchange (losses)			$ (2.7)	$ (0.4)	$ (0.2)
PocketSonics
Component Of Other Expense Income Nonoperating [Line Items]
Loss from pre-acquisition equity interest		$ (0.5)			$ (0.5)