Segment Information, Other Significant Reconciling Items by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Segment Information [Abstract]
Expenditures for long lived assets	$ (103,361)	$ (115,201)	$ (101,593)
Operating Segments [Member] | Research Publishing & Platforms [Member]
Segment Information [Abstract]
Expenditures for long lived assets	(24,284)	(16,329)	(12,928)
Operating Segments [Member] | Academic & Professional Learning [Member]
Segment Information [Abstract]
Expenditures for long lived assets	(41,897)	(38,229)	(32,337)
Operating Segments [Member] | Education Services [Member]
Segment Information [Abstract]
Expenditures for long lived assets	(3,449)	(613)	(3,160)
Corporate [Member]
Segment Information [Abstract]
Expenditures for long lived assets	$ (33,731)	$ (60,030)	$ (53,168)