Note 11 - Stock Options and Incentive Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended		25 Months Ended
	Mar. 17, 2020	Apr. 12, 2019	Jun. 30, 2022	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021	Nov. 30, 2016
Stock Issued During Period, Value, Issued for Services				$ 352
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares)				875,000	50,000	50,000
Share-Based Payment Arrangement, Expense				$ 357	$ 585
Butler National Corporation 2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)							12,500,000
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] | Director [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)			400,000	400,000
Shares Issued, Price Per Share (in dollars per share)			$ 0.88
Stock Issued During Period, Value, Issued for Services			$ 352
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)	5,000,000.0	2,500,000
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
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares)				875,000	50,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount				$ 842
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)				1 year 6 months