Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 176,426	$ 164,516	$ 120,308
Cost of sales	121,269	112,584	86,245
Gross profit	55,157	51,932	34,063
Selling, general and administrative	37,535	35,135	33,967
Research, development and engineering	7,800	6,372	8,004
Impairment charges	7,006	0	0
Restructuring charges	897	0	0
Operating income (loss)	1,919	10,425	(7,908)
Gain on sale of other assets	2,883	0	2,576
Income (loss) from equity method investment	234	(417)	299
Interest and other income (expense), net	489	(178)	(417)
Income (loss) before income taxes	5,525	9,830	(5,450)
Income tax provision	220	1,744	3,100
Net income (loss)	5,305	8,086	(8,550)
Add: Net loss attributable to non-controlling interest	0	1,045	1,542
Net income (loss) attributable to Amtech Systems, Inc.	$ 5,305	$ 9,131	$ (7,008)
Income (Loss) Per Share:
Basic income (loss) per share attributable to Amtech shareholders (dollars per share)	$ 0.36	$ 0.68	$ (0.53)
Weighted average shares outstanding (in shares)	14,833	13,378	13,168
Diluted income (loss) per share attributable to Amtech shareholders (dollars per share)	$ 0.35	$ 0.68	$ (0.53)
Weighted average shares outstanding (in shares)	15,065	13,501	13,168