Retirement Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 1,400	$ 1,100	$ 1,200
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.80%	2.60%	2.80%
Defined Benefit Plan, Interest Cost	$ 793	$ 809	$ 993
Defined Benefit Plan, Expected Return on Plan Assets	4.80%	4.80%	4.70%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ (992)	$ 35
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	(1,898)	2,897
Defined Benefit Plan, Plan Assets, Amount	13,360	14,110	$ 12,274
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	670	597
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	(786)	1,127
Defined Benefit Plan, Funded (Unfunded) Status of Plan	19,266	19,797
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	670	597	527
Defined Benefit Plan, Amortization of Gain (Loss)	(478)	(503)	(264)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	601	715	$ 730
Multi-asset Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4,570	4,784
Defined Growth Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4,649	5,009
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	2,044	2,173
Index-Linked Gilts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	2,044	$ 2,102
LumaSense Technology Holdings Inc. [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	100
Defined Benefit Plan, Expected Future Benefit Payments	100
HiTek Power Limited Pension Scheme [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 19,200