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Note 11 - Stock Options and Incentive Plans (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			9 Months Ended
	Mar. 17, 2020	Apr. 12, 2019	Jan. 31, 2022	Jan. 31, 2021	Nov. 30, 2016
Share-based Payment Arrangement, Expense			$ 437	$ 449
Butler National Corporation 2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)					12,500
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 2,000	$ 950
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)		0
Butler National Corporation 2016 Equity Incentive Plan [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	5,000	2,500
Share Price (in dollars per share)	$ 0.41	$ 0.38
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)		5 years