Discontinued Operations (Details Textual) - Discontinued Operations, Disposed of by Sale - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 19, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of shares sold			100.00%
Purchase price			$ 55,055
Net cash proceeds received			47,814
Amounts held in escrow			859
Transaction expenses			$ 2,099
High Voltage Product Line
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Milestone payments, 2019 and 2020	$ 7,500
Milestone payments due	15,000
Additional payments potentially due	5,000
Income from discontinued operations, net of income taxes	$ 7,894	$ 10,733