Common Stock (Tables)

12 Months Ended

Apr. 30, 2019

Class of Stock [Line Items]

Schedule of Common Stock Outstanding Roll Forward [Table Text Block]

The following table shows the change in outstanding common shares during each of the last three years:

	Outstanding
(Shares in thousands)	Class A		Class B		Total
Balance at April 30, 2016	169,060		325,293		494,353
Acquisition of treasury stock	(77	)	(14,768	)	(14,845	)
Stock issued under compensation plans	68		530		598
Balance at April 30, 2017	169,051		311,055		480,106
Acquisition of treasury stock	(25	)	(6	)	(31	)
Stock issued under compensation plans	36		890		926
Balance at April 30, 2018	169,062		311,939		481,001
Acquisition of treasury stock	(145	)	(4,212	)	(4,357	)
Stock issued under compensation plans	82		446		528
Balance at April 30, 2019	168,999		308,173		477,172

Schedule of Stock by Class [Table Text Block]

The following table shows the effects of the stock splits and treasury stock retirement on the number of issued common shares:

	Issued
(Shares in thousands)	Class A	Class B		Total
Balance at April 30, 2016	85,000	142,313		227,313
Stock split	85,000	142,313		227,313
Balance at April 30, 2017	170,000	284,626		454,626
Retirement of treasury stock	—	(67,000	)	(67,000	)
Stock split	—	96,906		96,906
Balance at April 30, 2018 and 2019	170,000	314,532		484,532