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Note 9 - Stock Options and Incentive Plans (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		6 Months Ended	9 Months Ended
	Apr. 12, 2019	Oct. 31, 2018	Jan. 31, 2020	Jan. 31, 2019	Nov. 30, 2016
Share-based Payment Arrangement, Noncash Expense, Total		$ 0	$ 142	$ 0
Butler National Corporation 2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					12,500
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 950
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	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	2,500
Share Price	$ 0.38
Deferred Compensation Equity, Ending Balance	$ 950
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years