Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss) attributable to Amtech Systems, Inc.	$ (12,101)		$ (2,965)		$ (18,386)	$ (8,920)
Weighted average shares outstanding (in shares)	9,539,000		9,479,000		9,524,000	9,468,000
Basic income (loss) per share attributable to Amtech shareholders (dollars per share)	$ (1.27)		$ (0.31)		$ (1.93)	$ (0.94)
Common stock equivalents (1) (in shares)	0	[1]	0	[1]	0	0
Diluted shares (in shares)	9,539,000		9,479,000		9,524,000	9,468,000
Diluted income (loss) per share attributable to Amtech shareholders (dollars per share)	$ (1.27)		$ (0.31)		$ (1.93)	$ (0.94)
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,100,000		892,000		1,100,000	892,000
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	72,000		133,000		72,000	133,000

[1] The number of common stock equivalents is calculated using the treasury stock method and the average market price during the period.