Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Revenue, net of returns and allowances	$ 164,516	$ 120,308	$ 104,883
Cost of sales	112,584	86,245	77,875
Gross profit	51,932	34,063	27,008
Selling, general and administrative	35,135	33,967	33,028
Research, development and engineering	6,372	8,004	6,918
Restructuring charges	0	0	583
Operating income (loss)	10,425	(7,908)	(13,521)
Gain on deconsolidation of Kingstone	0	0	8,814
Gain on sale of other assets	0	2,576	0
(Loss) income from equity method investment	(417)	299	0
Interest and other expense, net	(178)	(417)	(100)
Income (loss) before income taxes	9,830	(5,450)	(4,807)
Income tax provision	1,744	3,100	1,910
Net income (loss)	8,086	(8,550)	(6,717)
Add: Net loss (income) attributable to non-controlling interest	1,045	1,542	(1,054)
Net income (loss) attributable to Amtech Systems, Inc.	$ 9,131	$ (7,008)	$ (7,771)
Income (Loss) Per Share:
Basic loss per share attributable to Amtech shareholders (dollars per share)	$ 0.68	$ (0.53)	$ (0.65)
Weighted average shares outstanding (in shares)	13,378	13,168	12,022
Diluted loss per share attributable to Amtech shareholders (dollars per share)	$ 0.68	$ (0.53)	$ (0.65)
Weighted average shares outstanding (in shares)	13,501	13,168	12,022