Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		4 Months Ended	6 Months Ended		12 Months Ended
	Dec. 31, 2017	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2018	Apr. 30, 2017	Oct. 31, 2018
Income Tax [Line Items]
Effective tax rates		22.80%	31.80%		11.70%	30.60%
U.S. federal corporate income tax rate	35.00%			21.00%
Provisional tax benefit due to revaluation of tax assets and liabilities at reduced corporate tax rate		$ 45,213
Provisional tax expense to reflect the transition tax on previously deferred foreign earnings					$ 23,124
Decrease in income tax expense					$ 22,089
Payment of transition tax in installments, period					8 years
Discrete tax benefit		$ 2,202			$ 6,950
Discrete tax expense related to nondeductible acquisition costs			$ 2,600
Scenario Plan
Income Tax [Line Items]
U.S. federal corporate income tax rate							23.30%