Summary of Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	$ 12,388
Accumulated impairment losses	(1,269)
Goodwill, net, beginning of year	10,789	$ 11,119
Net foreign exchange differences	(330)
Goodwill, gross, end of quarter	11,968
Accumulated impairment losses	(1,179)
Goodwill, net, end of quarter	10,789
Solar
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	6,597
Accumulated impairment losses	(1,269)
Goodwill, net, beginning of year	4,998	5,328
Net foreign exchange differences	(330)
Goodwill, gross, end of quarter	6,177
Accumulated impairment losses	(1,179)
Goodwill, net, end of quarter	4,998
Semiconductor
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	5,063
Accumulated impairment losses	0
Goodwill, net, beginning of year	5,063	5,063
Net foreign exchange differences	0
Goodwill, gross, end of quarter	5,063
Accumulated impairment losses	0
Goodwill, net, end of quarter	5,063
Polishing
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	728
Accumulated impairment losses	0
Goodwill, net, beginning of year	728	$ 728
Net foreign exchange differences	0
Goodwill, gross, end of quarter	728
Accumulated impairment losses	0
Goodwill, net, end of quarter	$ 728