Discontinued Operations - Carrying Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Total current assets of discontinued operation	$ 68,334		$ 66,148
Total long-term assets of discontinued operation	61,967		59,052
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Total current liabilities of discontinued operation	8,335		7,388
Long-term liabilities of discontinued operation	506		698
Discontinued Operations, Held-for-sale | Semiconductor Cryogenics Business
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Accounts receivable, net	28,327		27,852
Inventories	39,884		37,953
Other current assets	123		343
Total current assets of discontinued operation	68,334		66,148
Property, plant and equipment, net	1,397		1,081
Goodwill	26,485		26,485
Intangibles, net	14		14
Equity method investment	34,053		31,472
Other assets	18
Total long-term assets of discontinued operation	61,967		59,052
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Deferred revenue	1,907	$ 1,532	1,052
Accrued warranty and retrofit costs	2,400		2,464
Accrued compensation and benefits	3,325		3,648
Other current liabilities	703		224
Total current liabilities of discontinued operation	8,335		7,388
Long-term liabilities of discontinued operation	$ 506		$ 698