Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Apr. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shareholders' equity	$ 1,298,699	$ 1,271,141
Deferred income taxes	$ (349,656)	(341,946)
GIft Cards | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shareholders' equity		879
Deferred revenue		(879)
Deferred income taxes		(321)
Box Tops | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shareholders' equity		(5,019)
Deferred revenue		5,019
Deferred income taxes		$ 1,816