Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue, net of returns and allowances	$ 85,035	$ 100,053	$ 83,073
Cost of sales	51,678	63,135	51,967
Gross profit	33,357	36,918	31,106
Selling, general and administrative	24,263	25,743	24,727
Research, development and engineering	3,068	2,856	2,738
Impairment charges	0	2,247	0
Restructuring charges	1,110
Operating income	4,916	6,072	3,641
Gain on sale of other assets		2,883
Income (loss) from equity method investment		234	(417)
Interest and other income, net	852	738	379
Income from continuing operations before income taxes	5,768	9,927	3,603
Income tax provision	2,633	3,296	1,409
Income from continuing operations, net of tax	3,135	6,631	2,194
(Loss) income from discontinued operations, net of tax	(8,297)	(1,326)	5,892
Net (loss) income	(5,162)	5,305	8,086
Net loss attributable to non-controlling interest - discontinued operations			1,045
Net (loss) income attributable to Amtech Systems, Inc.	$ (5,162)	$ 5,305	$ 9,131
Income (Loss) Per Basic Share:
Basic income per share from continuing operations	$ 0.22	$ 0.45	$ 0.16
Basic (loss) income per share from discontinued operations	(0.58)	(0.09)	0.52
Net (loss) income per basic share	(0.36)	0.36	0.68
Income (Loss) Per Diluted Share:
Diluted income per share from continuing operations	0.22	0.44	0.16
Diluted (loss) income per share from discontinued operations	(0.58)	(0.09)	0.52
Net (loss) income per diluted share	$ (0.36)	$ 0.35	$ 0.68
Weighted average shares outstanding - basic	14,240	14,833	13,378
Weighted average shares outstanding - diluted	14,275	15,065	13,501