Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenues, net of returns and allowances	$ 24,273us-gaap_SalesRevenueNet	$ 12,717us-gaap_SalesRevenueNet	$ 36,669us-gaap_SalesRevenueNet	$ 27,488us-gaap_SalesRevenueNet
Cost of sales	17,384us-gaap_CostOfGoodsAndServicesSold	9,819us-gaap_CostOfGoodsAndServicesSold	26,352us-gaap_CostOfGoodsAndServicesSold	20,055us-gaap_CostOfGoodsAndServicesSold
Gross profit	6,889us-gaap_GrossProfit	2,898us-gaap_GrossProfit	10,317us-gaap_GrossProfit	7,433us-gaap_GrossProfit
Selling, general and administrative	8,075	5,277	14,459	9,402
Research, development and engineering	750	2,155	2,586	3,044
Operating loss	(1,936)us-gaap_OperatingIncomeLoss	(4,534)us-gaap_OperatingIncomeLoss	(6,728)us-gaap_OperatingIncomeLoss	(5,013)us-gaap_OperatingIncomeLoss
Interest and other income, net	(217)us-gaap_OtherNonoperatingIncomeExpense	(20)us-gaap_OtherNonoperatingIncomeExpense	(120)us-gaap_OtherNonoperatingIncomeExpense	87us-gaap_OtherNonoperatingIncomeExpense
Loss before income taxes	(2,153)	(4,554)	(6,848)	(4,926)
Income tax provision	170us-gaap_IncomeTaxExpenseBenefit	0us-gaap_IncomeTaxExpenseBenefit	350us-gaap_IncomeTaxExpenseBenefit	560us-gaap_IncomeTaxExpenseBenefit
Net loss	(2,323)us-gaap_ProfitLoss	(4,554)us-gaap_ProfitLoss	(7,198)us-gaap_ProfitLoss	(5,486)us-gaap_ProfitLoss
Add: net loss (income) attributable to noncontrolling interest	2	803	(317)	941
Net loss attributable to Amtech Systems, Inc.	$ (2,321)us-gaap_NetIncomeLoss	$ (3,751)us-gaap_NetIncomeLoss	$ (7,515)us-gaap_NetIncomeLoss	$ (4,545)us-gaap_NetIncomeLoss
Loss Per Share:
Basic loss per share attributable to Amtech shareholders (dollars per share)	$ (0.19)us-gaap_EarningsPerShareBasic	$ (0.39)us-gaap_EarningsPerShareBasic	$ (0.69)us-gaap_EarningsPerShareBasic	$ (0.47)us-gaap_EarningsPerShareBasic
Weighted average shares outstanding (in shares)	11,997	9,679	10,914	9,619
Diluted loss per share attributable to Amtech shareholders (dollars per share)	$ (0.19)us-gaap_EarningsPerShareDiluted	$ (0.39)us-gaap_EarningsPerShareDiluted	$ (0.69)us-gaap_EarningsPerShareDiluted	$ (0.47)us-gaap_EarningsPerShareDiluted
Weighted average shares outstanding (in shares)	11,997	9,679	10,914	9,619

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