Assets Held for Sale and Discontinued Operations - Operating Results of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax (benefit) provision	$ (1,300)			$ (3,100)
Net income (loss)	1,154	$ (8)	$ (8,113)	6,517
Tempress and SoLayTec | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues, net of returns and allowances	5,268	12,457	19,649	70,620
Cost of sales	4,374	8,041	19,726	52,684
Gross profit (loss)	894	4,416	(77)	17,936
Selling, general and administrative	1,735	2,766	7,412	10,081
Research, development and engineering	736	1,540	2,647	4,260
Restructuring charges	(3)	0	598	0
Operating (loss) income	(1,574)	110	(10,734)	3,595
Gain on sale of subsidiary	1,614	0	1,614	0
Interest expense and other, net	(143)	(100)	(213)	(172)
(Loss) income from discontinued operations before income taxes	(103)	10	(9,333)	3,423
Income tax (benefit) provision	(1,257)	18	(1,220)	(3,094)
Net income (loss)	$ 1,154	$ (8)	$ (8,113)	$ 6,517