Discontinued Operations - Carrying Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Oct. 01, 2018	Sep. 30, 2018
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Total current assets of discontinued operation	$ 65,005		$ 66,148
Total long-term assets of discontinued operation	63,072		59,052
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Total current liabilities of discontinued operation	6,595		7,388
Long-term liabilities of discontinued operation	523		698
Discontinued Operations, Held-for-sale | Semiconductor Cryogenics Business
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Accounts receivable, net	25,675		27,852
Inventories	39,280		37,953
Other current assets	50		343
Total current assets of discontinued operation	65,005		66,148
Property, plant and equipment, net	1,499		1,081
Goodwill	26,485		26,485
Intangibles, net	15		14
Equity method investment	35,055		31,472
Other assets	18
Total long-term assets of discontinued operation	63,072		59,052
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Deferred revenue	1,082	$ 1,532	1,052
Accrued warranty and retrofit costs	2,303		2,464
Accrued compensation and benefits	2,839		3,648
Other current liabilities	371		224
Total current liabilities of discontinued operation	6,595		7,388
Long-term liabilities of discontinued operation	$ 523		$ 698