Note 11 - Stock Options and Incentive Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	Mar. 17, 2020	Apr. 12, 2019	Jul. 31, 2022	Jul. 31, 2022	Jul. 31, 2021	Nov. 30, 2016
Share-Based Payment Arrangement, Expense				$ 484	$ 148
Stock Issued During Period, Value, Issued for Services				$ 352
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
Shares Issued, Price Per Share (in dollars per share)			$ 0.88	$ 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