Provision for Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Dec. 31, 2017	Apr. 30, 2018	Apr. 30, 2017	Jul. 31, 2018
Income Tax [Line Items]
Effective income tax rate	25.90%	33.10%		32.80%	33.00%
Corporate tax rate	21.00%		35.00%
Additional income tax expense benefit due to change in tax rate				$ 34,000
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions	$ 2,990			2,990
Expected decrease in interest due to resolution of uncertain tax positions				$ 330
Scenario Forecast
Income Tax [Line Items]
Corporate tax rate						26.90%