Revenue Recognition and Contracts with Customers - Schedule of Adjustments to Condensed Consolidated Balance Sheet on Adoption of ASU 2014-09 (Detail) - USD ($) $ in Thousands	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	May 01, 2018	Apr. 30, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accrued expenses and deferred revenue	$ 37,515				$ 41,632
Deferred revenue from contracts with customers	7,786	$ 8,951	$ 13,621		23,305
Deferred income taxes	11,118				12,895
Retained earnings	$ 393,122				$ 389,146
ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accrued expenses and deferred revenue				$ 24,456
Deferred revenue from contracts with customers				23,305
Deferred income taxes				11,376
Retained earnings				384,536
ASU 2014-09 | Accounting Standard Adjustments
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accrued expenses and deferred revenue				(17,176)
Deferred revenue from contracts with customers				23,305
Deferred income taxes				(1,519)
Retained earnings				$ (4,610)