Agreement and Plan of Merger - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Apr. 30, 2018	Apr. 30, 2018	Apr. 10, 2018	Jul. 31, 2017
Business Acquisition [Line Items]
Common stock, par value	$ 0.05	$ 0.05		$ 0.05
ANLG Holding Company, Inc. and AC Merger Sub, Inc.
Business Acquisition [Line Items]
Date of merger agreement		Apr. 10, 2018
Merger agreement, price per share of common stock			$ 84.00
Common stock, par value			$ 0.05
Contingent merger termination fee payable to Parent			$ 34.8
Contingent merger termination fee receivable from Parent			$ 64.2
Pre-tax expenses related to professional fees	$ 4.1
Business combination, debt financing comments obtained by Parent	$ 575.0	$ 575.0