Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues, net of returns and allowances	$ 73,611	$ 29,135
Cost of sales	53,274	20,692
Gross profit	20,337	8,443
Selling, general and administrative	10,580	6,996
Research, development and engineering	1,991	1,627
Operating income (loss)	7,766	(180)
Loss from equity method investment	(26)	(143)
Interest expense and other income, net	(48)	81
Income (loss) before income taxes	7,692	(242)
Income tax provision	1,240	90
Net income (loss)	6,452	(332)
Add: net loss attributable to noncontrolling interest	0	279
Net income (loss) attributable to Amtech Systems, Inc.	$ 6,452	$ (53)
Income (Loss) Per Share:
Basic income (loss) per share attributable to Amtech shareholders (USD per share)	$ 0.44	$ 0.00
Weighted average shares outstanding (in shares)	14,781	13,179
Diluted income (loss) per share attributable to Amtech shareholders (USD per share)	$ 0.42	$ 0.00
Weighted average shares outstanding (in shares)	15,298	13,179

Research And Development, Net Of Grants

No definition available.

Name:	asys_ResearchAndDevelopmentNetOfGrantsEarned
Namespace Prefix:	asys_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.