BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																								12 Months Ended
	Jan. 31, 2014		Apr. 30, 2013		Oct. 31, 2012		Jul. 31, 2012		Apr. 30, 2012		Jan. 31, 2012		Oct. 31, 2011		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2011		Oct. 31, 2010		Jul. 31, 2010		Apr. 30, 2013		Apr. 30, 2012		Apr. 30, 2011
Accounts receivable [Abstract]
Allowance for doubtful accounts			$ 51						$ 58																$ 51		$ 58
Inventories [Abstract]
Obsolete inventory			1,400						1,093																1,400		1,093
Supplemental Type Certificates [Abstract]
Direct labor			566						444																566		444
Direct materials			1,244						1,120																1,244		1,120
Consultant costs			1,922						1,922																1,922		1,922
Overhead			886						691																886		691
Supplemental Type Certificates capitalized, gross			4,618						4,177																4,618		4,177
Less-amortized costs			2,604						2,500																2,604		2,500
STC balance			2,014						1,677																2,014		1,677
Revenue Recognition [Abstract]
Period for payment due																									30 days
Warranty period, minimum																									90 days
Warranty period, maximum																									36 months
Earnings Per Share [Abstract]
Net income (loss) attributable to Butler National Corporation	(755)		225		114		268		765		568		459		108		31		867		473		(112)		(148)		1,900		1,259
Weighted average common shares outstanding (in shares)																									59,014,594		56,596,214		56,108,812
Dilutive effect of non-qualified stock option plans (in shares)																									0		0		0
Weighted average common shares outstanding, assuming dilution (in shares)																									59,014,594		56,596,214		56,108,812
Potential common shares if all options were exercised and shares issued (in shares)																									66,281,237		64,848,201		63,856,326
Basic earnings per common share (in dollars per share)	$ (0.01)	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.03	[1]	$ 0.02	[1]
Diluted earnings per common share (in dollars per share)	$ (0.01)	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.01	[1]	$ 0.01	[1]			$ 0.00	[1]	$ 0.03	[1]	$ 0.02	[1]
Cash and Cash Equivalents [Abstract]
Bank deposits that exceeded the federally insured limits									1,218																		1,218
Research and Development [Abstract]
Research and development expense																									1,652		1,652
Kansas Expanded Lottery Act Management Contract Privilege Fee [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Other assets intangible			5,500						5,500																5,500		5,500
Less amortized costs intangible			564						141																564		141
Other assets net intangible, net			4,936						5,359																4,936		5,359
Gaming Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life																									3 years
Finite-Lived Intangible Assets, Net [Abstract]
Other assets intangible			1,182						0																1,182		0
Less amortized costs intangible			148						0																148		0
Other assets net intangible, net			1,034						0																1,034		0
JET Autopilot Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life																									15 years
Amortization as a percentage of gross sales (in hundredths)																									5.00%
Finite-Lived Intangible Assets, Net [Abstract]
Other assets intangible			1,417						1,417																1,417		1,417
Less amortized costs intangible			491						397																491		397
Other assets net intangible, net			$ 926						$ 1,020																$ 926		$ 1,020
Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful lives of property																									3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful lives of property																											39 years

[1] Rounded to nearest hundredth