Income Taxes (Tax carry forwards) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Research and development credits	$ 8,449	$ 6,840
Tax Credit Carryforward, Amount	500
Deferred tax assets decrease	(400)	$ 5,200
Tax Credit Carryforward, Limitations on Use	600
Federal | Federal R&D tax credits carryforwards [Member]
Tax Credit Carryforward [Line Items]
Research and development credits	5,300
State | State R&D tax credits carryforwards [Member]
Tax Credit Carryforward [Line Items]
Research and development credits	$ 5,900