Note 1 - Nature of Operations, Organization and Significant Accounting Policies - Computation of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Net income attributable to Butler National Corporation	$ 10,368	$ 1,433
Weighted average common shares outstanding (in shares)	75,340,131	74,144,957
Dilutive effect of non-qualified stock option plans (in shares)	0	0
Weighted average common shares outstanding, assuming dilution (in shares)	75,340,131	74,144,957
Potential common shares if all options were exercised and shares issued (in shares)	75,340,131	74,144,957
Basic earnings per common share (in dollars per share)	$ 0.14	$ 0.02
Diluted earnings per common share (in dollars per share)	$ 0.14	$ 0.02