Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenues, net of returns and allowances	$ 32,783	$ 32,944	$ 106,394	$ 62,079
Cost of sales	21,058	24,549	74,332	45,241
Gross profit	11,725	8,395	32,062	16,838
Selling, general and administrative	9,478	8,260	20,058	15,258
Research, development and engineering	2,182	1,535	4,173	3,163
Operating income (loss)	65	(1,400)	7,831	(1,583)
Income (loss) from equity method investment	28	52	2	(91)
Interest expense and other income, net	(38)	(197)	(86)	(116)
Income (loss) before income taxes	55	(1,545)	7,747	(1,790)
Income tax (benefit) provision	(2,780)	194	(1,540)	284
Net income (loss)	2,835	(1,739)	9,287	(2,074)
Add: net loss attributable to noncontrolling interest	0	319	0	599
Net income (loss) attributable to Amtech Systems, Inc.	$ 2,835	$ (1,420)	$ 9,287	$ (1,475)
Income (Loss) Per Share:
Basic income (loss) per share attributable to Amtech shareholders (USD per share)	$ 0.19	$ (0.11)	$ 0.63	$ (0.11)
Weighted average shares outstanding (in shares)	14,891	13,188	14,835	13,184
Diluted income (loss) per share attributable to Amtech shareholders (USD per share)	$ 0.19	$ (0.11)	$ 0.61	$ (0.11)
Weighted average shares outstanding (in shares)	15,154	13,188	15,223	13,184