Income Taxes (Net Operating Loss Carryforwards and Tax Credits) (Narrative) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Tax Credit Carryforward [Line Items]
Operating loss carryforwards, carried forward indefinetly	$ 32,258
Federal [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	195,856
Tax credit carryforwards, research	8,631
State [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	8,610
Tax credit carryforwards, research	4,761
Foreign [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	34,309
Tax credit carryforwards, research	26,869
General foreign tax credit	163
Canada Revenue Agency [Member] | Foreign [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards, research	$ 121,076