INDUSTRY SEGMENTATION AND SALES BY MAJOR CUSTOMER (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Apr. 30, 2014 Customer	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2014 Segment Customer		Apr. 30, 2013		Apr. 30, 2012
INDUSTRY SEGMENTATION AND SALES BY MAJOR CUSTOMER [Abstract]
Number of primary activities													2
Segment Reporting Information [Line Items]
Total revenues	$ 14,632	$ 10,844	$ 10,799	$ 10,996	$ 12,326	$ 10,651	$ 13,152	$ 13,023	$ 13,938	$ 13,309	$ 13,725	$ 11,747	$ 47,271		$ 49,152		$ 52,719
Depreciation and amortization													3,495		3,276		2,199
Operating income (loss)	1,958	18	(198)	143	38	(520)	700	1,285	1,864	1,568	1,380	674	1,921		1,503		5,486
Capital Expenditures, net													290		8,159		3,534
Interest Expense													(1,417)		(1,521)		(736)
Other income (expense)													43		11		(11)
Income (loss) before taxes													547		(7)		4,739
Income tax expense (benefit)													33		(816)		823
Net income (loss) attributable to Butler National Corporation	965	(219)	(345)	(289)	225	(755)	114	268	765	568	459	108	112		(148)		1,900
Identifiable assets net	41,678				43,860				40,562				41,678		43,860		40,562
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)													17.80%
Number of major customers	5												5
Top Customer [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)													6.10%
Next Top Four Customers [Member] | Minimum [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)													1.20%
Next Top Four Customers [Member] | Maximum [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)													5.50%
Modifications [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)														[1]		[1]		[1]
Avionics [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)														[1]		[1]		[1]
Management Services [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)														[1]		[1]		[1]
Environmental Services [Member]
Revenue, Major Customer [Line Items]
Revenue from major customers (in hundredths)														[1]		[1]		[1]
Professional Services [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues													31,022		35,525		35,531
Depreciation and amortization													1,676		1,285		364
Operating income (loss)													1,819		2,987		2,928
Capital Expenditures, net													148		7,180		2,211
Interest Expense													0		0		0
Other income (expense)													0		0		0
Income (loss) before taxes													0		0		0
Income tax expense (benefit)													0		0		0
Net income (loss) attributable to Butler National Corporation													0		0		0
Identifiable assets net	22,091				23,880				19,535				22,091		23,880		19,535
Aerospace Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues													16,249		13,627		17,188
Depreciation and amortization													1,819		1,991		1,835
Operating income (loss)													102		(1,484)		2,558
Capital Expenditures, net													142		979		1,323
Interest Expense													0		0		0
Other income (expense)													0		0		0
Income (loss) before taxes													0		0		0
Income tax expense (benefit)													0		0		0
Net income (loss) attributable to Butler National Corporation													0		0		0
Identifiable assets net	$ 19,587				$ 19,980				$ 21,027				$ 19,587		$ 19,980		$ 21,027

[1] Revenue represented less than 10% of consolidated revenue.