Consolidated Balance Sheets (Parenthetical) - $ / shares	Apr. 30, 2018	Apr. 30, 2017
Treasury stock, shares	3,531,000	88,175,000
Common stock, Class A, voting [Member]
Common stock, par value	$ 0.15	$ 0.15
Common stock, shares authorized	170,000,000	170,000,000
Common Stock, Class B, nonvoting [Member]
Common stock, par value	$ 0.15	$ 0.15
Common stock, shares authorized	400,000,000	400,000,000