Summary of Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2016	Sep. 30, 2015
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	$ 11,808
Accumulated impairment losses	(1,273)
Goodwill, net, beginning of year	11,188	$ 10,535
Goodwill recognized due to acquisitions	600
Net foreign exchange differences	53
Goodwill, gross, end of quarter	12,476
Accumulated impairment losses	(1,288)
Goodwill, net, end of quarter	11,188
Operating Segments | Solar
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	6,617
Accumulated impairment losses	(1,273)
Goodwill, net, beginning of year	5,397	5,344
Goodwill recognized due to acquisitions	0
Net foreign exchange differences	53
Goodwill, gross, end of quarter	6,685
Accumulated impairment losses	(1,288)
Goodwill, net, end of quarter	5,397
Operating Segments | Semiconductor
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	4,463
Accumulated impairment losses	0
Goodwill, net, beginning of year	5,063	4,463
Goodwill recognized due to acquisitions	600
Net foreign exchange differences	0
Goodwill, gross, end of quarter	5,063
Accumulated impairment losses	0
Goodwill, net, end of quarter	5,063
Operating Segments | Polishing
Goodwill [Roll Forward]
Goodwill, gross, beginning of year	728
Accumulated impairment losses	0
Goodwill, net, beginning of year	728	$ 728
Goodwill recognized due to acquisitions	0
Net foreign exchange differences	0
Goodwill, gross, end of quarter	728
Accumulated impairment losses	0
Goodwill, net, end of quarter	$ 728