Note 16 - Subsequent Events (Details Textual) - Subsequent Event [Member] - Board Member [Member]	1 Months Ended
Jun. 30, 2022 USD ($) shares
Compensation Expense, Excluding Cost of Good and Service Sold \| $	$ 140,000
Butler National Corporation 2016 Equity Incentive Plan [Member] \| Other Stock-based Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) \| shares	400,000

Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit. Other employee benefit expense includes, but is not limited to, service component of net periodic benefit cost for defined benefit plan. Excludes compensation cost in cost of good and service sold.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(4))
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

Name:	us-gaap_CompensationExpenseExcludingCostOfGoodAndServiceSold
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration