CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - $ / shares shares in Thousands	Apr. 30, 2021	Apr. 30, 2020
Shareholders' equity
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	2,000	2,000
Preferred stock, shares issued (in shares)	0	0
Class A [Member]
Shareholders' equity
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	180,000	180,000
Common stock, shares issued (in shares)	70,208	70,166
Treasury shares at cost (in shares)	23,419	23,405
Class B [Member]
Shareholders' equity
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	72,000	72,000
Common stock, shares issued (in shares)	12,974	13,016
Treasury shares at cost (in shares)	3,922	3,920