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Income Taxes (Summary of Operating Loss Carryforwards and Tax Credit Carryforwards) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Net deferred tax asset, net operating loss	$ 16,305	$ 19,058
Total net deferred tax asset	20,045	22,472
Total valuation allowance	14,131	15,522
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
Net deferred tax asset, net operating loss	16,531	16,624
Valuation allowance, net operating loss	13,668	13,182
Net deferred tax asset, tax credit carryforwards, research		1,198
Net deferred tax asset, alternative minimum tax credit	1,596	2,310
Valuation allowance, tax credit	0	0
Federal tax authority
Operating Loss Carryforwards [Line Items]
Net deferred tax asset, tax credit carryforwards, research	1,455
Valuation allowance, tax credit	0
Foreign tax authority
Operating Loss Carryforwards [Line Items]
Net deferred tax asset, net operating loss		2,340
Valuation allowance, net operating loss		$ 2,340
Net deferred tax asset, alternative minimum tax credit	463
Valuation allowance, tax credit	$ 463

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