Declaration of Dividend Payable (Details) - $ / shares		3 Months Ended				6 Months Ended
	Aug. 19, 2020	Oct. 31, 2020		Oct. 31, 2019		Oct. 31, 2020	Oct. 31, 2019
Dividends [Abstract]
Cash dividends declared per common share (in usd per share)	$ 0.11	$ 0.11	[1]	$ 0.11	[1]	$ 0.22	$ 0.22

[1] Basic per share amounts are the same for Class A and Class B shares. Diluted per share amounts for Class A shares are shown above. Diluted earnings per share for Class B shares under the two-class method are $0.02 and $0.06 for the three months ended October 31, 2020 and 2019 and $0.09 and $0.10 for the six months ended October 31, 2020 and 2019. See Note E to the Condensed Consolidated Financial Statements.