Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
CURRENT ASSETS:
Cash	$ 16,793	$ 9,014
Accounts receivable, net of allowance for doubtful accounts	2,784	3,265
Asset held for sale, net of accumulated depreciation		447
Income tax receivable		27
Inventories
Parts and raw materials	6,892	7,370
Work in process	1,661	1,441
Finished goods	62	74
Total inventory, net of allowance	8,615	8,885
Prepaid expenses and other current assets	1,620	1,646
Total current assets	29,812	23,284
PROPERTY, PLANT AND EQUIPMENT:
Finance lease right-to-use assets	44,349	1,699
Land and building	5,805	5,765
Aircraft	8,511	8,467
Machinery and equipment	4,093	4,085
Office furniture and fixtures	8,533	7,477
Leasehold improvements	4,032	4,032
Property, Plant and Equipment, Gross, Ending Balance	75,323	31,525
Accumulated depreciation	(20,577)	(16,714)
Total property, plant and equipment	54,746	14,811
SUPPLEMENTAL TYPE CERTIFICATES (net of accumulated amortization of $7,029 at April 30, 2020 and $6,054 at April 30, 2019)	6,483	6,407
OTHER ASSETS:
Deferred tax asset	331	295
Other assets (net of accumulated amortization of $10,153 at April 30, 2020 and $9,370 at April 30, 2019)	3,546	4,105
Total other assets	3,877	4,400
Total assets	94,918	48,902
CURRENT LIABILITIES:
Current maturities of long-term debt	2,228	1,899
Current maturities of finance lease liability	1,163	8
Accounts payable	962	1,774
Customer deposits	1,994	2,758
Gaming facility mandated payment	1,338	1,280
Compensation and compensated absences	2,571	1,664
Deferred tax liability, current	191	236
Income tax payable	206
Other current liabilities	274	230
Total current liabilities	10,927	9,849
Long-term debt, net of current maturities	3,211	2,076
Finance lease liability, net of current maturities	42,211	1,689
Deferred tax liability	765	944
Total long-term liabilities	46,187	4,709
Total liabilities	57,114	14,558
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Common stock, par value $.01: authorized 100,000,000 shares issued 77,719,677 shares, and outstanding 74,398,262 shares at April 30, 2020 and issued 71,008,122 shares, and outstanding 68,281,071 shares at April 30, 2019	777	710
Capital contributed in excess of par	15,600	14,767
Treasury stock at cost, 3,321,415 shares at April 30, 2020 and 2,727,051 shares at April 30, 2019	(1,713)	(1,387)
Retained earnings	18,147	13,913
Total Butler National Corporation's stockholders' equity	32,811	28,003
Noncontrolling interest in BHCMC, LLC	4,993	6,341
Total stockholders' equity	37,804	34,344
Total liabilities and stockholders' equity	94,918	48,902
Preferred Class A [Member]
STOCKHOLDERS' EQUITY:
Preferred stock
Preferred Class B [Member]
STOCKHOLDERS' EQUITY:
Preferred stock