Discontinued Operations - Financial Results (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Net income (loss)	$ 6,333	$ (182)	$ 20,731
Discontinued Operations, Held-for-sale | Semiconductor Cryogenics Business
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Total revenue	34,540		109,518
Total cost of revenue	21,739		66,164
Gross profit	12,801		43,354
Research and development	2,279		6,605
Selling, general and administrative	4,808	(171)	17,005
Restructuring charges	24		24
Total operating expenses	7,111	(171)	23,634
Operating income	5,690	171	19,720
Other income (loss), net	418	(410)	985
Income (loss) before income taxes and earnings of equity method investment	6,108	(239)	20,705
Income tax provision (benefit)	1,610	(57)	4,850
Income (loss) before equity in earnings of equity method investment	4,498	(182)	15,855
Equity in earnings of equity method investment	1,835		4,876
Net income (loss)	6,333	$ (182)	20,731
Discontinued Operations, Held-for-sale | Semiconductor Cryogenics Business | Products
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Total revenue	23,546		76,227
Total cost of revenue	15,451		47,148
Discontinued Operations, Held-for-sale | Semiconductor Cryogenics Business | Services
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Total revenue	10,994		33,291
Total cost of revenue	$ 6,288		$ 19,016