Discontinued Operations - Carrying Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Total current assets of discontinued operation	$ 66,148	$ 60,671
Total long-term assets of discontinued operation	59,052	56,553
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Total current liabilities of discontinued operation	7,388	7,825
Long-term liabilities of discontinued operation	698	652
Semiconductor Cryogenics Business | Held-for-sale
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Accounts receivable, net	27,852	27,363
Inventories	37,953	32,998
Other current assets	343	310
Total current assets of discontinued operation	66,148	60,671
Property, plant and equipment, net	1,081	1,481
Goodwill	26,485	26,485
Intangibles, net	14	16
Equity method investment	31,472	28,570
Other assets		1
Total long-term assets of discontinued operation	59,052	56,553
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Deferred revenue	1,052	1,728
Accrued warranty and retrofit costs	2,464	2,574
Accrued compensation and benefits	3,648	3,189
Other current liabilities	224	334
Total current liabilities of discontinued operation	7,388	7,825
Long-term liabilities of discontinued operation	$ 698	$ 652