Discontinued Operations (Statement of Operations) (Details) - Discontinued Operations, Disposed of by Sale - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale, net of income taxes	$ 5,400
High Voltage Product Line
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue		$ 5,414
Cost of revenue		3,051
Gross profit		2,363
Selling, general and administrative		1,789
Research and development		624
Total operating expenses		2,413
Income from operations of discontinued operations		(50)
Other components of defined benefit plans, net		249
Other income and expense, net		(38)
Income tax benefit (provision)		1,148
Income from discontinued operations, net of income taxes		$ 1,309