Summary of Significant Accounting Policies - ASC 606 - Cumulative Effect - Balance Sheet - Discontinued Operations (Details) - Discontinued Operations, Held-for-sale - Semiconductor Cryogenics Business - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets - discontinued operations		$ 578	$ 343
Deferred revenue - discontinued operations	$ 1,907	1,532	$ 1,052
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets - discontinued operations		235
Deferred revenue - discontinued operations		$ 480