SUMMARY OF QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) (USD $) In Thousands, except Per 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
SUMMARY OF QUARTERLY FINANCIAL INFORMATION (UNAUDITED) [Abstract]
Revenues	$ 11,000		$ 12,824		$ 13,537		$ 13,468		$ 14,393		$ 13,734		$ 14,141		$ 12,146		$ 12,913		$ 12,860		$ 11,016		$ 9,546		$ 50,829		$ 54,414		$ 46,335
Operating income (loss)	(520)		38		700		1,285		1,864		1,568		1,380		674		598		1,514		780		(64)		1,503		5,486		2,828
Non-operating income (expense)	(417)		(425)		(331)		(337)		(390)		(179)		(92)		(86)		(96)		(84)		(89)		(130)		(1,510)		(747)		(399)
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
Basic Earnings (Loss) per 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 (Loss) per 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]

[1] Rounded to nearest hundredth