Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 4,971	$ 2,841	$ 14,258	$ 767
Foreign currency translation adjustment	(2,181)	740	(844)	118
Comprehensive income	2,790	3,581	13,414	885
Comprehensive loss attributable to noncontrolling interest	0	302	0	969
Comprehensive income attributable to Amtech Systems, Inc.	$ 2,790	$ 3,883	$ 13,414	$ 1,854