CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($)	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024
Supplemental type certificates, accumulated amortization	$ 12,145,000	$ 11,810,000
Other assets, accumulated amortization	$ 12,461,000	$ 13,041,000
Preferred stock, par value (in dollars per share)	$ 5	$ 5
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares, issued (in shares)	79,772,345	79,646,211
Common stock, shares, outstanding (in shares)	67,180,527	68,770,856
Treasury stock, shares (in shares)	12,591,818	10,875,355
Preferred Class A
Preferred stock, designated classes (in shares)	200,000	200,000
Preferred stock, stated value (in dollars per share)	$ 100	$ 100
Preferred stock, dividend rate, percentage	9.80%	9.80%
Preferred stock, liquidation preference, value	$ 100	$ 100
Preferred stock, redemption amount	$ 100	$ 100
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred Class B
Preferred stock, designated classes (in shares)	200,000	200,000
Preferred stock, stated value (in dollars per share)	$ 1,000	$ 1,000
Preferred stock, dividend rate, percentage	6.00%	6.00%
Preferred stock, liquidation preference, value	$ 1,000	$ 1,000
Preferred stock, redemption amount	$ 1,000	$ 1,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0