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Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Taxes [Abstract]
Unrecognized tax benefits	$ 3,400			$ 3,400
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ 300			$ 300
Effective tax rate	25.30%		33.30%	25.00%	46.40%
Deferred income taxes	$ 7,638	$ 7,360		$ 7,638
Taxes on foreign earnings repatriated			$ 2,500
Reversal of taxes on foreign earnings repatriated due to 2017 Tax Act		$ (1,600)
Unremitted earnings of foreign subsidiaries	8,700			8,700
Unrecognized deferred tax liability on unremitted earnings of foreign subsidiaries	500			500
Internal Revenue Service (IRS) \| Tax Years 2011, 2012 and 2013
Income Taxes [Abstract]
Disallowed research tax credits being litigated	$ 2,500			2,500
Internal Revenue Service (IRS) \| Tax Years 2011 to Date
Income Taxes [Abstract]
Income Tax Credits and Adjustments				$ 10,000